Practitioner Issue 4, 2020

Published by the Florida Association of Equine Practitioners, an Equine-Exclusive Division of the FVMA

Issue 4

•

2020

PRACTICAL ULTRASOUND OF THE EQUINE STIFLE: PART ONE SUZAN C. OAKLEY

DVM, DACVSMR, DABVP (EQUINE)

GETTING STARTED ON THE RIGHT FOOT TRACY A. TURNER

DVM, MS, DACVS, DACVSMR

TOOLS OF REHABILITATION: PART ONE SARAH PLEVIN

BVMS, MRCVS, CVA, DABVP, DACVSMR, RCVS SPECIALIST

The President's Line Fellow practitioners,

EXECUTIVE COUNCIL RUTH-ANNE RICHTER

BSc (Hon), DVM, MS FAEP COUNCIL PAST PRESIDENT

rrichter@surgi-carecenter.com

ADAM CAYOT DVM

adamcayot@hotmail.com

SALLY A. L. DENOTTA

I hope this finds you well as we kick off a fresh, new year! Now that we have vaccines being distributed, we hope for a return to some version of normal in the coming months.

Despite the trying times, equine practitioners appear to have made it through 2020 while managing to balance our health with the continued care of our patients. As we progress into winter, we will have some of our northern clients returning and it will begin to get busier—it’s always a good thing to be busy!

To help our practitioners obtain continuing education credits in a safe and convenient way, the FAEP/FVMA is now offering virtual CE through LINK, your live interactive network for knowledge. As we await a return to normal, I find it relaxing to get my CE while at home. I look forward to the day when we can all safely gather for our in-person meetings and interact with our peers and industry representatives. We continue to plan for the 16th Annual Promoting Excellence Symposium (PES) to be an in-person meeting in October of 2021.

s.denotta@ufl.edu

We have opened registration and soon hope to welcome you to the beautiful Naples Grande Resort in Naples, Florida!

COREY MILLER

As always, our publication is strong and contains excellent information that’s practical and useful to our readers. The folks who unfailingly put it together are incredible. We also want to thank our industry sponsors who do so much for us and support us at all times.

cmiller@emcocala.com

Please take care as we look ahead to better days.

ANNE L. MORETTA

Armon Blair, DVM FAEP Council President

DVM, PhD

DVM, MS, DACT

VMD, MS, CVSMT, CVA

maroche1@aol.com

JACQUELINE S. SHELLOW DVM, MS REPRESENTATIVE TO FVMA EXECUTIVE BOARD

jackie@shellow.com

If anyone is feeling too stressed or mentally unwell, please do not hesitate to reach out to colleagues, friends, or the FAEP (call 800.992.3862).

Opinions and statements expressed in The Practitioner reflect the views of the contributors and do not represent the official policy of the Florida Association of Equine Practitioners or the Florida Veterinary Medical Association, unless so stated.

Placement of an advertisement does not represent the FAEP’s or FVMA’s endorsement of the product or service.

FAEP | 7207 MONETARY DRIVE, ORLANDO, FL 32809 | PH: 800.992.3862 | FAX: 407.240.3710 | EMAIL: INFO@FVMA.ORG | WEBSITE: WWW.FAEP.NET

2 The Practitioner

Issue 4 • 2020

There’s nothing else like it.

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Reduce inflammation Restore synovial joint lubrication Repair joint cartilage Reverse the disease cycle When you start with it early and stay with it as needed, horses may enjoy greater mobility 2, 4, 5 over a lifetime. Discover if Adequan is the right choice. Talk to your American Regent Animal Health sales representative or call (800) 458-0163 to order.

BRIEF SUMMARY: Prior to use please consult the product insert, a summary of which follows: CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: Adequan® i.m. is recommended for the intramuscular treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal and hock joints in horses. CONTRAINDICATIONS: There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. WARNINGS: Do not use in horses intended for human consumption. Not for use in humans. Keep this and all medications out of the reach of children. PRECAUTIONS: The safe use of Adequan® i.m. in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. For customer care, or to obtain product information, visit www.adequan.com. To report an adverse event please contact American Regent, Inc. at (800) 734-9236 or email pv@americanregent.com.

Please see Full Prescribing Information at www.adequan.com.

www.adequan.com 1 Data on file.

2 Adequan® i.m. Package Insert, Rev 1/19.

3 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model. J Equine Vet Sci 1993; 13: 696-703.

4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57.

5 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse.St. Louis, MO: Elsevier, 2016; 33-48.

All trademarks are the property of American Regent, Inc. © 2020, American Regent, Inc. PP-AI-US-0372 02/2020

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Elevate® W.S.

when fast action is required.

• When administered, Elevate W.S. will quickly increase circulating blood levels of vitamin E. • Elevate W.S. vitamin E is readily available and effective in crossing the blood-brain barrier.

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4 The Practitioner

Elevate® Concentrate

for long-term supplementation.

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Issue 4 • 2020

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PRACTICAL ULTRASOUND OF THE EQUINE STIFLE Part One: Medial and Cranial Approaches SUZAN C. OAKLEY | DVM, DACVSMR, DABVP (EQUINE)

INTRODUCTION WHY ULTRASOUND THE STIFLE

Lameness originating in the stifle is common and is often under diagnosed in performance horses. Traditional indications for stifle ultrasound are swelling in the stifle area and lameness localized to the stifle. Horses with less severe or bilateral stifle pain may present for poor performance, behavioral issues, or back pain. Any horse with stifle pain or undiagnosed rear limb lameness can benefit from an ultrasound exam of the stifle.

Ultrasound is a practical, high yield diagnostic procedure to evaluate the ligaments, menisci, synovium, cartilage, and bone surfaces of the stifle. Ultrasound is more sensitive than radiography at detecting changes in bone surfaces1 and the combination of these techniques provides a more complete picture than radiography alone.2 Ultrasound is more sensitive than radiography to early signs of joint disease such as synovitis and new bone production. Periarticular bone changes and osteophytes are indicative of primary or secondary degenerative joint disease.3 Early detection of degenerative joint disease allows appropriate treatment for the health of the joint and the comfort of the horse.

HOW TO ULTRASOUND THE STIFLE

This article describes the basic ultrasound examination of the stifle. Part one will address the medial and cranial approaches.

Anatomical knowledge of the area being imaged is essential and is the basis for interpretation of ultrasound images. The relevant anatomical dissection is paired with reference ultrasound images for that area so the practitioner can gain a better understanding of the anatomy pertaining to each ultrasound image. It is important to examine all structures in the stifle to determine the cause of inflammation and/or the extent of the injury.

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HOW TO GET A DIAGNOSTIC-QUALITY ULTRASOUND IMAGE? PREPARATION AND ENVIRONMENT

If the horse has a long hair coat, it should be clipped. In field practice, the stifle can often be adequately imaged without clipping if the hair is short and alcohol can be used instead of gel. (All images in this article were obtained without clipping, although some horses had been body clipped.) Washing with soap and rinsing to remove all dirt is very important and will greatly improve image quality. When possible, wetting the limb prior to the exam will also improve image quality. A dark environment is optimal and will help avoid the use of excessive gain to see the image during the exam.

ERGONOMICS AND PROBE HANDLING

Stifle ultrasound can be performed standing or seated on a rolling stool, whichever is more comfortable for the operator. The ultrasound screen should be adjusted to an appropriate height to prevent slouching to see the screen. The ultrasound machine should be in the line of vision of the operator to prevent twisting of the operator’s neck.

Image quality is greatly affected by how you hold the ultrasound probe. Do not grip the probe with excessive pressure because hand, wrist, and shoulder tension decrease fine motor control. Stand or sit close to the horse so your upper arm is in a relaxed position by your side to minimize shoulder tension. On the cranial and lateral aspects of the limb, it can be helpful to use one hand to stabilize the probe on the leg to prevent slipping and the other hand to manipulate the probe. Keep the probe handle clean and dry so it is easy to hold. A slippery probe handle covered in gel will cause the operator to grip the probe with excessive pressure causing tension, loss of fine motor control, and decreased image quality.

Issue 4 • 2020

PROBE SELECTION AND MACHINE SETTINGS

for gain, frequency, focal zones, and depth are appropriate. The image should be centered in the screen and probe should be oriented perpendicular (transverse axis) or parallel (longitudinal axis) to the structure being imaged with no twisting of the probe.

Off incidence views may be helpful to define tendon or ligament margins and identify scar tissue,4 but shouldn’t be inadvertently used. It is important to image all structures in both transverse and longitudinal axes to confirm a lesion.

LABELING AND IMAGE ORIENTATION

MEDIAL APPROACH – MEDIAL FEMOROTIBIAL JOINT

A high-frequency linear probe is used for the basic examination of the medial, cranial, and lateral aspects of the stifle. A standoff is not usually necessary. Most superficial structures can be scanned at a depth of two to four centimeters. A depth of six centimeters is usually required for examination of the lateral aspect of the stifle joint. A micro convex transducer may also be used for the evaluation of the lateral aspect of the stifle on large horses.

All images should be labeled with owner name, horse name, and limb at a minimum. When comparing sides in split screen mode, it is helpful to put the left leg on the left side of the screen and the right leg on the right side of the screen. There are several methods of image orientation. In this article, proximal, cranial, and medial are on the left in all images.

TECHNIQUE AND ARTIFACTS

It is important to be familiar with normal anatomy and common artifacts to differentiate injury from artifact. Proper ultrasound technique is essential to avoid misdiagnosis. Be sure the settings

The medial femorotibial joint (MFTJ) recess, medial aspect of the medial meniscus, and the medial collateral ligament are evaluated from the medial approach. The medial recess of the MFTJ can be considered a “window” into the joint. Effusion, hypertrophic synovial villi, thickening of the joint capsule, or echogenic debris indicate synovitis.

Place the probe in long axis (vertical to the ground) orientation at the proximal margin of the tibia between the medial patellar ligament and the medial collateral ligament (MCL) at position A indicated on the anatomy specimen (Figure 1). The medial recess of the MFTJ is proximal to the medial meniscus (MM). The MM is homogeneously echogenic when the probe is perpendicular to the fibers and should not protrude past an imaginary line from the femur to the tibia. Slide the probe caudally to evaluate the MM until the MCL is reached (position B). The angle of the probe must be adjusted to maintain perpendicular orientation to the curved surface of the meniscus. Follow the MCL proximally and distally to image its origin and insertion. The best image of the MCL is sometimes at a probe angle where the MM is hypoechoic. Turn the probe 90 degrees to evaluate the structures in short axis orientation. In short axis, the cross section of the MCL is hypoechoic at the level of the MM due to the spiral nature of the ligament.

The MM should also be evaluated in a non-weight bearing position, as this may increase the visibility of small tears.

Artifacts are common when imaging the MM. Radial shadows are anechogenic artifacts caused by refraction at the outer surface of the meniscus.7 They remain perpendicular to the probe and should not be mistaken for tears.

Figure 1. Anatomical specimen showing medial aspect of the stifle joint.

Image courtesy of Dr. Suzan C. Oakley.

Legend pertains to the anatomical dissections and ultrasound images.

1. Femur 2. Tibia 3. Medial femorotibial joint recess 4. Medial meniscus 5. Medial collateral

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Legend pertains to the anatomical dissections and ultrasound images.

REFERENCE IMAGES:

1. Femur 2. Tibia 3. Medial femorotibial joint recess 4. Medial meniscus 5. Medial collateral

Figure 2. Long axis image at probe position (A) in Figure 1. Pictured in (a), normal medial recess of the medial femorotibial joint and medial meniscus. In (b) and (c), normal medial menisci with vertical hypoechoic striations (arrows). These artifacts are perpendicular to the ultrasound probe and disappear when probe angle is changed.

Image courtesy of Dr. Suzan C. Oakley.

Figure 3. Composite long axis image of the medial collateral ligament (MCL) at probe position B. The image is focused on MCL; the hypoechoic areas in MM are artifacts.

Image courtesy of Dr. Suzan C. Oakley.

Figure 4. (a) Short axis image of the medial collateral ligament at its origin on the femur (b) at the level of the medial meniscus (medial meniscus is between arrows) and (c) at its insertion on the tibia. The medial collateral ligament is outlined by the dotted yellow line.

Image courtesy of Dr. Suzan C. Oakley.

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Issue 4 • 2020

CRANIAL APPROACH – FEMOROPATELLAR JOINT The medial trochlear ridge, lateral trochlear ridge, medial, and lateral recesses of the femoropatellar joint, medial patellar ligament, lateral patellar ligament, and intermediate (middle) patellar ligaments are examined from the cranial aspect of the stifle with the limb weightbearing. The middle patellar ligament is referred to as the intermediate6 patellar ligament for clarity.

There is normally no fluid visible in the medial femoropatellar recess. Synovitis, effusion, OCD (usually lateral trochlear ridge), and cartilage irregularities can be diagnosed as well as injuries to the patellar ligaments.

It is easiest to evaluate the trochlear ridges from proximal to distal in short axis orientation first and then in long axis. The lateral patellar ligament is directly over the lateral trochlear ridge, and the intermediate patellar ligament lies in the trochlear groove.

Irregularities in the bone surface of the trochlear groove can be normal. The cartilage of the lateral trochlear ridge is thicker than on the medial trochlear ridge.

Figure 5. Anatomical specimen showing cranial aspect of the stifle joint.

Image courtesy of Dr. Suzan C. Oakley.

Legend pertains to the anatomical dissections and ultrasound images.

1. Medial trochlear ridge 2. Trochlear groove 3. Lateral trochlear ridge 4. Lateral recess of femoropatellar joint (seen on ultrasound image) 5. Medial patellar ligament 6. Intermediate patellar ligament 7. Lateral patellar ligament 8. Tibia 9. Fibula 10. Patella 11. Peripatellar fibrocartilage

Figure 6. (a) A normal short axis image of the medial and lateral trochlear ridges and trochlear groove. (b) Normal lateral trochlear ridge and lateral recess of femoropatellar joint. Note the rounded profile of the medial trochlear ridge compared to the steep slope of the lateral trochlear ridge.

Image courtesy of Dr. Suzan C. Oakley.

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Figure 7. (a) Normal long axis image of medial trochlear ridge and (b) the lateral trochlear ridge. Note that the cartilage (hypoechoic area between arrows) is thicker on the lateral trochlear ridge than the medial trochlear ridge.

Image courtesy of Dr. Suzan C. Oakley.

INTERMEDIATE PATELLAR LIGAMENT The intermediate patellar ligament is easily palpable and has a proximolateral to distomedial orientation. It is very important to adjust the angle of the probe as you scan from proximal to distal in short axis to maintain perpendicular orientation to the ligament to prevent off incidence artifacts. The ligament is surrounded by the infrapatellar fat pad and has fat within

it so artifacts are common. Hypoechoic lines at insertion are usually a result of fat or endotendon tissue7 within the ligament. Hypoechoic areas can be seen mid ligament so it is important to compare it to the other side if there is a question of lesion vs. artifact.

REFERENCE IMAGES:

Figure 8. (a) Normal short axis image of the intermediate patellar ligament at its origin on the patella, (b) mid-body, and (c) at its tibial insertion.

Image courtesy of Dr. Suzan C. Oakley.

Figure 9. (a) Normal long axis image of the intermediate patellar ligament at its origin on the patella, (b) mid-body, and (c) at its tibial insertion. Note that the intermediate patellar ligament is deep proximally and superficial distally.

Image courtesy of Dr. Suzan C. Oakley.

10 The Practitioner

Issue 4 • 2020

Figure 10. Artifacts: Common artifacts seen in the intermediate patellar ligament: (a) and (b) hypoechoic areas in mid-body due to off incidence artifact, and (c) hypoechoic lines at insertion due to fat or endotendon tissue between the ligament fibers.7 Image courtesy of Dr. Suzan C. Oakley.

MEDIAL AND LATERAL PATELLAR LIGAMENTS The medial patellar ligament is on the medial aspect of the cranial stifle. It is thin and closely associated with the joint capsule. It is triangular in cross section and is easiest to scan from the tibial insertion moving proximally to the peripatellar fibrocartilage.

The lateral patellar ligament is crescent shaped and lies directly over the lateral trochlear ridge.

REFERENCE IMAGES:

Figure 11. (a) Normal short axis image of the medial patellar ligament at its origin on peripatellar fibrocartilage, (b) mid-body, and (c) at its insertion on the tibia.

Image courtesy of Dr. Suzan C. Oakley.

Figure 12. (a) Normal short axis image of the lateral patellar ligament at its origin on the patella, (b) over the lateral trochlear ridge, and (c) at its insertion on the tibia.

Image courtesy of Dr. Suzan C. Oakley.

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Figure 13. (a) Normal long axis image of the medial patellar ligament at mid-body. (b) Normal long axis image of lateral patellar ligament at mid-body over the lateral trochlear ridge. Note the more obvious linear fiber pattern in the lateral patellar ligament.

Image courtesy of Dr. Suzan C. Oakley.

EXAMPLES OF PATHOLOGY MEDIAL FEMOROTIBIAL JOINT

Figure 14. (a) Normal medial femorotibial joint recess (MFTJ). (b) Abnormal MFTJ showing echogenic debris. (c) Effusion, hypertrophic synovial villi, and thickening of joint capsule (arrows) are present.

Image courtesy of Dr. Suzan C. Oakley.

MEDIAL MENISCUS

Figure 15. (a) Normal medial meniscus (MM). (b) Small tear (arrow) in MM. (c) MM showing irregular echogenicity. Bone margins of femur and tibia are irregular.

Image courtesy of Dr. Suzan C. Oakley.

12 The Practitioner

Issue 4 • 2020

MEDIAL COLLATERAL LIGAMENT

Figure 16. (a) Normal long axis image of the origin of the medial collateral ligament (MCL) on the femur. (b) Chronic injury to the MCL origin demonstrating abnormal size, shape, margins, echogenicity, and fiber pattern.

Image courtesy of Dr. Suzan C. Oakley.

LATERAL TROCHLEAR RIDGE

Figure 17. (a) Normal short axis image of lateral trochlear ridge (LTR). (b) OCD lesion of LTR. Arrow indicates free bone fragment above irregular subchondral bone margin.

Image courtesy of Dr. Suzan C. Oakley.

References

1. Werpy NM. Equine Imaging Modalities. In: Proceedings 7. Cauvin ERJ (2014). Ultrasonography of the Stifle.

AAEP 2010; 56:300 In: Kidd, Lu and Frazer (Ed.), Atlas of Equine 2. Denoix JM, Audige,F. (2004) Imaging of the Ultrasonography (pp. 161-181) Musculoskeletal System in Horses. In: Equine Sports Medicine and Surgery (pp 166-171) Recommended Reading 3. Denoix JM, Audige, F. Ultrasonographic Examination of • Busoni V. Ultrasonographic Assessment of Cranial Joints in Horses. In: Proceedings AAEP2001; 47:374 Meniscal Ligaments in the Horse. In: Proceedings of the 4. Werpy NM, Axiak L. Review of Innovative Ultrasound European Association of Vet Diagnostic Imaging 2003; Techniques for the Diagnosis of Muscu-loskeletal Injury.

39 In: Proc AAEP 2013; 59: 209-219.

• Budras KD, Sack WO, Rock S. (2011) Anatomy of the 5. Bourzac C, Alexander K, Rossier Y, Laverty S. Horse. (p. 24) Radiography and Ultrasonography for Diagnosis of • Cauvin ERJ (2014). Ultrasonography of the Stifle.

Osteochondritis Dissecans in the Femoropatellar Joint.

In: Kidd, Lu and Frazer (Ed.), Atlas of Equine In: Proc AAEP 2009; 55:454 Ultrasonography (pp. 161-181) 6. Budras KD, Sack WO, Rock S. (2011) Anatomy of the Horse. (p. 24)

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Zimeta™ (dipyrone injection) 500mg/mL injection For intravenous use in horses Non-steroidal anti-inflammatory drug (NSAID)

• • • • • •

Denoix JM. Ultrasonographic Examination of the Stifle in horses. In: Proceedings of the Annual Meeting of the ACVS 2003; 122.

Dik K. Ultrasonography of the Equine Stifle. Equine Vet Educ 1995; 7:154-160 Dyson SJ. Normal Ultrasonographic Anatomy and Injury of the Patellar Ligaments in the Horse. Equine Vet J 2002; 34:258-264 Hoegarts M, Saunders JH. How to perform a Standard Ultrasonographic Examination of the Equine Stifle. In: Proc AAEP 2004; 50:212-218.

Werpy NM, Axiak L. Review of Innovative Ultrasound Techniques for the Diagnosis of Musculoskeletal Injury.

In: Proc AAEP 2013; 59: 209-219.

Whitcomb MB, Review of Techniques to Improve Musculoskeletal Image Quality. In Proc AAEP 2009; 55: 431-437

Notes • All ultrasound images were obtained by Dr. Oakley with a SonoSite Edge II or SonoSite Edge.

• All anatomical dissections were done by Dr. Oakley.

• Anatomical dissections and ultrasound images were not enhanced.

Dr. Suzan C. Oakley, DVM, DACVSMR, DABVP (Equine) Dr. Suzan C. Oakley is a 1991 graduate of the University of Florida.

She is the owner of a sports medicine practice in Wellington, Florida. Dr. Oakley is board certified by the American College of Sports Medicine and Rehabilitation and the American Board of Veterinary Practitioners in Equine Practice and is a certified member of the International Society for Equine Locomotor Pathology (ISELP). Dr. Oakley has an avid interest in sport horses, lameness, and the use of ultrasound as a diagnostic tool.

CAUTION: Federal law (U.S.A.) restricts this drug to use by or on the order of a licensed veterinarian.

Before using this product, please consult the product insert, a summary of which follows: Indication: Zimeta™ (dipyrone injection) is indicated for the control of pyrexia in horses.

Dosage and Administration: Always provide the Client Information Sheet with the prescription. Administer Zimeta by intravenous injection, once or twice daily, at 12 hour intervals, for up to three days, at a dosage of 30 mg/kg (13.6 mg/lb). See product insert for complete dosing and administration information.

Contraindications: Horses with hypersensitivity to dipyrone should not receive Zimeta. Due to the prolongation of prothrombin time (PT) and associated clinical signs of coagulopathy, dipyrone should not be given more frequently than every 12 hours.

Warnings: For use in horses only. Do not use in horses intended for human consumption.

Do not use in any food producing animals, including lactating dairy animals.

Human Warnings: Care should be taken to ensure that dipyrone is not accidentally injected into humans as studies have indicated that dipyrone can cause agranulocytosis in humans.

Not for use in humans. Keep this and all drugs out of reach of children. In case of accidental exposure, contact a physician immediately.

Direct contact with the skin should be avoided. If contact occurs, the skin should be washed immediately with soap and water.

As with all injectable drugs causing profound physiological effects, routine precautions should be employed by practitioners when handling and using loaded syringes to prevent accidental self-injection.

Table 1: Adverse Reactions Reported During the Field Study with Zimeta

Adverse Reaction Elevated Serum Sorbitol Dehydrogenase (SDH) Hypoalbuminemia

ZimetaTM Control (dipyrone Product injection) (N=31) (N=107) 5 (5%) 5 (16%) 3 (3%)

1 (3%)

Gastric Ulcers

2 (2%)

0 (0%)

Hyperemic Mucosa Right Dorsal Colon Prolonged Activated Partial Thromboplastin Time (APTT) Elevated Creatinine Injection Site Reaction Anorexia

1 (1%)

0 (0%)

1 (1%)

0 (0%)

1 (1%) 1 (1%)

0 (0%) 0 (0%)

1 (1%)

1 (3%)

See Product Insert for complete Adverse Reaction information.

Information for Owners or Person Treating Horse: A Client Information Sheet should be provided to the person treating the horse. Treatment administrators and caretakers should be aware of the potential for adverse reactions and the clinical signs associated with NSAID intolerance. Adverse reactions may include colic, diarrhea, and decreased appetite. Serious adverse reactions can occur without warning and, in some situations, result in death. Clients should be advised to discontinue NSAID therapy and contact their veterinarian immediately if any signs of intolerance are observed.

Effectiveness: The effectiveness phase was a randomized, masked, controlled, multicenter, field study conducted to evaluate the effectiveness of Zimeta™ (dipyrone injection) administered intravenously at 30 mg/kg bodyweight in horses over one year of age with naturally occurring fevers. Enrolled horses had a rectal temperature ≥102.0°F. A horse was considered a treatment success if 6 hours following a single dose of study Precautions: Horses should undergo a drug administration the rectal temperature thorough history and physical examination decreased ≥2.0°F from hour 0, or the temperature decreased to normal (≤101.0°F). before initiation of any NSAID therapy.

As a class, NSAIDs may be associated with platelet dysfunction and coagulopathy. Zimeta has been shown to cause prolongation of coagulation parameters in horses. Therefore, horses on Zimeta should be monitored for clinical signs of coagulopathy.

Caution should be used in horses at risk for hemorrhage.

As a class, NSAIDs may be associated with gastrointestinal, renal, and hepatic toxicity.

Sensitivity to drug-associated adverse events varies with the individual patient. Consider stopping therapy if adverse reactions, such as prolonged inappetence or abnormal feces, could be attributed to gastrointestinal toxicity. Patients at greatest risk for adverse events are those that are dehydrated, on diuretic therapy, or those with existing renal, cardiovascular, and/or hepatic dysfunction. Concurrent administration of potentially nephrotoxic drugs should be carefully approached or avoided. Since many NSAIDs possess the potential to produce gastrointestinal ulcerations and/or gastrointestinal perforation, concomitant use of Zimeta with other anti-inflammatory drugs, such as NSAIDs or corticosteroids, should be avoided. The influence of concomitant drugs that may inhibit the metabolism of Zimeta has not been evaluated. Drug compatibility should be monitored in patients requiring adjunctive therapy.

The safe use of Zimeta in horses less than three years of age, horses used for breeding, or in pregnant or lactating mares has not been evaluated. Consider appropriate washout times when switching from one NSAID to another NSAID or a corticosteroid.

Adverse Reactions: Adverse reactions reported in a controlled field study of 138 horses of various breeds, ranging in age from 1 to 32 years of age, treated with Zimeta (n=107) or control product (n=31) are summarized in Table 1. The control product was a vehicle control (solution minus dipyrone) with additional ingredients added to maintain masking during administration.

One hundred and thirty-eight horses received treatment (104 Zimeta and 34 control product) and 137 horses (103 Zimeta and 34 control product) were included in the statistical analysis for effectiveness. At 6 hours post-treatment, the success rate was 74.8% (77/103) of Zimeta treated horses and 20.6% (7/34) of control horses. The results

of the field study demonstrate that Zimeta administered at 30 mg/kg intravenously was effective for the control of pyrexia 6 hours following treatment administration.

Refer to the Product Insert for complete Effectiveness information.

Storage Information: Store at Controlled Room Temperature 20° and 25°C (68° and 77°F); with excursions permitted between 15° and 30°C (59° and 86°F). Protect from light.

Multi-dose vial. Use within 30 days of first puncture.

How Supplied: Zimeta is available as a 500mg/mL solution in a 100mL, multi-dose vial.

Approved by FDA under NADA # 141-513 NDC 86078-245-01 Manufactured for: Kindred Biosciences, Inc. 1555 Bayshore Hwy, Suite 200, Burlingame, CA 94010 To report adverse reactions call Kindred Biosciences, Inc. at 1-888-608-2542.

Zimeta™ is a trademark of Kindred Biosciences, Inc. ©2019 Kindred Biosciences, Inc. All rights reserved.

Rev. 11-2019 KB50002_ZIV-BS-1

Now available from Dechra! *

For more information, visit Zimeta.com

For 24-hour Veterinary Technical Support, contact Dechra Veterinary Products at: 866-933-2472 | www.dechra-us.com | support@dechra.com

Zimeta is indicated for the control of pyrexia in horses

Important Safety Information Zimeta® (dipyrone injection) should not be used more frequently than every 12 hours. For use in horses only.

Do not use in horses with a hypersensitivity to dipyrone, horses intended for human consumption or any food producing animals, including lactating dairy animals. Not for use in humans, avoid contact with skin and keep out of reach of children. Take care to avoid accidental self-injection and use routine precautions when handling and using loaded syringes. Prior to use, horses should undergo a thorough history and physical examination.

Monitor for clinical signs of coagulopathy and use caution in horses at risk for hemorrhage. Concomitant use with other NSAIDs, corticosteroids and nephrotoxic drugs, should be avoided. As a class, NSAIDs may be associated with gastrointestinal, renal, and hepatic toxicity. The most common adverse reactions observed during clinical trials were Eleveated Serum Sorbitol Dehydrogenase (SDH), Hypoalbuminemia and Gastric Ulcers.

For additional information, see brief summary of prescribing information on the following page.

References: 1. Zimeta® (dipyrone injection). [Full Prescribing Information], Kindred Biosciences, Inc. (Burlingame, CA).

Revised: 03/2019. 2. Morresey PR, et al. Randomized blinded controlled trial of dipyrone as a treatment for pyrexia in horses. Am J Vet Res. 2019;80(3):294-299.

Zimeta® is a registered trademark of Kindred Biosciences, Inc. ©2020 Dechra Veterinary Products, LLC. All rights reserved. 04AD-ZEM50315-0121

Update

GETTING STARTED ON THE RIGHT FOOT TRACY A. TURNER | DVM, MS, DACVS, DACVSMR INTRODUCTION

“No foot, no horse” is a common phrase indicating the importance of the hoof to the mature equine athlete. However, it is decisions and management concerning feet and limbs during the first two years of life that produce a strong foundation for the animal’s future athletic career. Unfortunately, not all recognize the importance and influence of hoof care during this period as affecting the horse’s long-term future. This article will focus on routine farriery in young horses and those limb deformities that can be addressed through farriery.

EVALUATING THE HOOF

Good record keeping is important. Records are designed for the individual needs of the farm/owner and should reflect the physical appearance of a foal's feet and limbs at birth and any subtle changes that occur during development, on at least a monthly basis. Digital images (pictures and radiographs) can be taken and added to the foal's record. Pictures are very helpful in determining changes in the foal’s feet/limbs. Foals should always be observed walking each time they are trimmed. The author prefers to observe the foal walking before the feet and limbs are examined. Watching the young foal walk can be challenging as it seldom walks in a straight line. This can be remedied by walking the mare along a fence or wall and letting the foal walk alongside or follow the mare. The foal is observed as it walks toward and away from the examiner. Here the foal is evaluated for any lameness that may be present, the pattern of the foot flight, how the foot breaks over at the toe and how the foot contacts the ground. When examining the feet and limbs from the front, it is useful to use imaginary lines through the bones. This way it is easy to see if, and/or where, an angular limb deformity exists.

However, one must be careful to note the presence of a rotational deformity. In these cases, both carpi are rotated outward, leading to a toe out or splay-footed conformation, yet axial alignment of the limb forms a straight line. The coronary band is observed to see if it is level or parallel with the ground. Examining the feet and limbs from the side should note whether the carpus is flexed or hyperextended. The hoof-pastern axis is evaluated to determine if it is aligned and not broken forward (flexural deformity) or broken backward (flexor flaccidity). Any swellings along the limb or involving the physis are noted and recorded.

Each deformity is noted and should be scored on a scale of one to five; grade one being mild, while grade five is severe. Finally, the foot is evaluated off the ground, observing its position relative to the bones of the digit, symmetry of the foot, and the integrity of 16 The Practitioner

the horny structures of the foot. The above examination enables the examiner to evaluate the feet, limbs, and movement in a systematic manner.

TRIMMING THE FOAL Birth to One Month At birth, the foal's hoof is enveloped in a gelatinous perioplic membrane, which reduces the risk of trauma to the mare's reproductive tract during birth. Shortly after birth, with the first steps of life, the perioplic membrane on the solar surface of the foot wears and retracts proximally on the hoof wall and dries out.

The foal's foot will be tapered, being wider at the coronet and becoming narrower distally at the ground surface. A foal's foot does not only grow in a distal direction, it also expands. As the foal's feet are tapered, expansion occurs proximally, and as the ground surface of the distal hoof is relatively small, the weightbearing area is positioned dorsally. Exercise and trimming will enlarge the area on the ground surface of the foot and move it in a palmar/plantar direction. The pointed or tapered appearance will gradually disappear in the first few months of life. In foals with acceptable limb conformation, there is little need for trimming during the first month of life.

One Month Foals should be presented to the farrier at one month of age for routine trimming. All that will generally be necessary at this time is to square or roll the toe of the hoof to encourage the foal to break over in the center of the foot. At this age, due to the pointed toe, the foal may break over to either the outside or inside of the toe. This first farrier examination will also allow the foal to get used to having its feet handled. The farrier should be patient, and the trimming procedure should be performed as gently and efficiently as possible.

Two to Six Months In the first few months of life, attention should be directed toward the structural integrity of the foot (foot mass) rather than to cosmetics. The important issues here are to promote the growth of thick, durable hoof wall, to ensure maximum sole depth in order to protect the vulnerable sole wall junction and developing distal phalanx, and to develop the structures in the palmar/ plantar section of the foot. The structural mass of foot, defined as a strong hoof wall, adequate sole depth and a solid heel base, is vital for future soundness. It is the opinion of many authors that a hoof pick, wire brush, and a rasp are the only tools necessary to Issue 4 • 2020

Figure 1a. A nice round edge is made by running the rasp around the perimeter of the hoof.

Image courtesy of Dr. Steve O'Grady.

Figure 1b. Using the rasp on an angle leaves the hoof wall and the adjacent sole on the same plane.

Image courtesy of Dr. Steve O'Grady.

trim foals that are kept on a monthly schedule. The goal is not to have the foal walk entirely on the hoof wall, but to load all the structures on the bottom of the foot. This makes the foot load sharing. Foals that are trimmed frequently and have a lot of horn removed tend to develop weak fragile hoof walls.

to lower one side of the foot past the point of being level due to a developing hoof capsule distortion or to affect landing, it should not be any more than two-three millimeters at one time.

Trimming at two-week intervals may be useful in this situation.

Dr. Steve O’Grady has described an excellent technique for trimming these foals. Dirt and debris is removed from the foot using a hoof pick. The bottom of the foot is then cleaned vigorously using a wire brush to remove any loose exfoliating horn.

Otherwise, the ground surface of the foot and the frog are left untouched. This affords the foal ample protection on the ground surface of the foot. Horn from the sole will be continuously shed through an abrasive mechanism with the ground as the foal exercises. The sole in the foot of a foal is extremely thin and as much protection as possible is necessary to protect the immature developing structures above. Removing excess sole with a hoof knife is a primary cause of sole bruising in foals and often leads to flexural deformities as a result of the pain response. The health of the foot throughout the animal's life is based on a good, solid heel area. The heel base includes the hoof wall at the heel, the bars, and a nice wide frog. The bars are needed to stabilize the hoof capsule and are never removed. The heels are rasped gently from side to side until the rasp just comes in contact with the frog. The hoof wall at the heels will now be on the same plane with the frog.

The excess hoof wall at the toe and quarters is then lowered as necessary, using a rasp placed at a 90° angle, just in front of the sole wall junction (white line). When the desired amount of hoof wall is removed, the outer sharp edge of the angle is removed by running the rasp around the perimeter of the hoof, thus creating a nice, rounded edge (Figure 1a). This will help to prevent cracks and chips in the hoof wall. The method of using the rasp on an angle leaves the hoof wall and the adjacent sole on the same plane, allowing both structures to share the bulk of the weight when the animal moves (Figure 1b). This appears to stimulate the horn to grow thicker and stronger. Foals do not grow an excessive amount of hoof wall in the first few months of life and our ability to influence the foot/limb by excessive trimming on one side of the foot in the horizontal plane is limited. If it becomes necessary WWW.FAEP.NET |

The traditional theory of lowering the lateral side of the foot on a foal that stands toed-out and lowering the medial side of the foot on a toed-in foal is inaccurate. In fact, it is more likely to be harmful than beneficial. The cause of the foal having a toe-in or toe-out stance is rarely in the foot. The problem is generally found in the axial alignment of the limb above the foot; therefore, when one side of the foot is lowered excessively, the cosmetic appearance may be improved, but over time, will lead to distortion of the hoof capsule. Or worse, this practice will place stresses on the physis and overload the joints on the side that is being lowered. This can be shown radiographically a few days after trimming and may lead to axial skeleton issues later in life.

ROTATIONAL LIMB DEFORMITIES

Rotational deformities are very common in foals. Most are due to the foal's narrow chest combined with the relatively long limbs, which cause many foals to adopt a base-wide stance in front. This is often accompanied by outward rotation of the entire limb. As the foal moves, the outside hoof wall of the foot contacts the ground first due to the foot flight pattern caused by the rotated position of the limb. These foals should be trimmed level and not have their feet lowered on the outside wall. If attempts are made to "correct" this physiologic stance by lowering the lateral wall, there is a risk of creating an angular limb deformity where none existed previously. Therapeutic trimming does not offer favorable results in the rotationally malpositioned limb as this deformity is corrected through growth. As the musculature of the chest increases, the elbows are pushed outward, rotating the limbs inward.

ANGULAR LIMB DEFORMITIES

Angular limb deformities are common limb abnormalities in foals that require early recognition and treatment.1,2,4 The primary lesion is an imbalance of physeal growth; for various reasons, FLORIDAAEP |

@FLORIDA_VMA | The Practitioner 17

growth proceeds faster on one side of the physis. Angular limb deformities can be further classified based on the direction of the deviation. Valgus deformities occur when the deviation occurs lateral to the axis of the limb, and varus deformities occur when the deviation is medial to the axis of the limb. The most common location of valgus angular limb deformity is the carpus, while varus deformities are most often seen at the fetlock.

Mild carpal valgus deviations of two-five degrees are considered acceptable. However, deviations exceeding five-eight degrees become a concern and should be monitored (Figure 2a).

Radiographs should be part of the physical examination in a foal with an angular limb deformity. Occasionally, osseous abnormalities such as hypoplastic carpal bones will preclude correction of the problem without splints or a cast. Radiographs will also reveal the site and degree of deviation and allow comparison at a later date. Conservative therapy for the management of many angular limb deformities may be successful in the newborn foal. A few days of stall confinement on firm bedding or limited exercise in a small paddock (two-three times a day) is a rewarding, cost-effective treatment for the early carpal valgus. This allows the physis to be stimulated but prevents stress and compression on the affected side of the growth plate. If the knee can be corrected by applying pressure with one hand on the inside of the knee and counter pressure with the other hand applied to the outside of the fetlock, then a splint made from polyvinylchloride (PVC) pipe fitted from the elbow to the fetlock applied for a few hours daily may be useful. A full-length bandage is applied to the limb first, and then the PVC pipe is placed on the outside of the limb and secured with a bandage. This will distract the carpus laterally. The splint is often the most cost-effective treatment available but must be applied with caution.

Mild to moderate valgus will generally respond to restricted exercise and the use of a composite extension applied to the

Figure 2b. The extension on the side away from the deviation redirects the forces on the physis on the overloaded side of the limb by moving the plane of weight bearing toward the midline.

Image courtesy of Dr. Steve O'Grady.

medial side of the foot, while the more severe cases require surgical intervention combined with farriery. The extension on the medial side and toward the heels redirects the forces on the physis on the overloaded side of the limb by moving the plane of weight bearing toward the midline (Figure 2b).3 The extension also promotes centerline breakover. The extension can be made from any number of materials. The material is applied directly to the foot and shaped to the desired width. It is trimmed like normal hoof as the foot grows distally, or additional applications can be applied if necessary. In severe cases of carpal valgus where surgery is necessary, a medial extension is combined with the surgery. Carpal valgus angular limb deformities respond well to surgery. Intervention up to four months of age has an excellent prognosis for full correction. After four months, the prognosis is dependent on the severity of the deformity and the age of the horse when correction is attempted.

Varus deformities usually involve the fetlock in either the front or hind limb of foals. This deformity can be congenital or acquired within the first few weeks of life. A varus fetlock deformity requires early detection and treatment, as functional closure of the distal physis of the third metatarsal/metacarpal bone is approximately 12 weeks of age. Foals with fetlock varus should have their exercise restricted and will generally respond to an extension applied to the lateral side of foot. The window of opportunity for treatment is small and the extension should be applied at two-three weeks of age. Caution must be used because the exothermic reaction of the extension materials could damage the sensitive tissues of the young foal. In severe cases, surgical intervention will be necessary, combined with an extension. If the foal is presented for treatment after 30 days of age, treatment becomes difficult and less effective.

FLACCID TENDONS AND TENDON LAXITY Figure 2a. Deviations exceeding 5-8 degrees are a concern.

Image courtesy of Dr. Steve O'Grady.

18  The Practitionerâ€

Flexor tendon flaccidity is a relatively common limb deformity seen in newborn foals usually involving the hind limbs but may Issue 4 • 2020

Figure 3a. Flexor tendon laxity is a relatively common limb deformity seen in newborn foals usually involving the hind limbs.

Image courtesy of Dr. Steve O'Grady.

affect all four limbs (Figure 3a). This condition is thought to be the cause of digital hyperextension, where weight-bearing is on the palmar/plantar aspect of the phalanges and the toe of the hoof is raised off the ground. The condition often tends to self-correct within days after birth as the foal gains strength and is allowed moderate exercise. However, the tendon laxity can persist. It is not uncommon to see a foal that still has digital hyperextension at four weeks of age. Treatment is sequential depending on the severity of the tendon laxity and the response of the foal to treatment. Therapy is based on controlled exercise and therapeutic trimming plus shoeing (if necessary). The foal is allowed access to a small area with firm footing for one hour three times daily.

The toe of the foot can be shortened, and the heels can be rasped gently from the middle of the foot palmarly/plantarly to create ground surface, and a palmar/plantar extension can be applied if necessary. This extension which extends approximately three to four centimeters behind the bulbs of the heels immediately relieves the laxity (Figure 3b). There are several different shoes that have appropriate extension that can be used. Although some apply these with adhesives, many believe that in these young foals’ shoes should only be taped on. It is believed that the heat generated by composites as they cure may damage the sensitive tissues of the hoof in foals less than three weeks of age. Regardless of the method of application, the extensions should be changed at 10-day intervals. Bandaging the limb is contraindicated as this will cause further laxity of the tendons.

FLEXURAL DEFORMITIES Flexural deformities have been traditionally referred to as "contracted tendons." This is a misnomer, as the primary defect is a shortening of the musculotendonous unit, not a contraction of the tendon portion, making "flexural deformity" the preferred term.1,4 This shortening produces a unit of functional length less than necessary for normal limb alignment of the digit, resulting in fixed flexion of the various joints of the distal limb, especially the distal interphalangeal joint.

WWW.FAEP.NET |

Figure 3b. The heel extension extends three to four centimeters behind the bulbs of the heels immediately relieves the laxity.

Image courtesy of Dr. Steve O'Grady.

Congenital flexure deformities are thought to result from intrauterine positioning, genetics, nutritional management of the mare during gestation and the influenza virus, but no causes have been proven. These deformities involve a combination of joints in the distal limb causing the foal to assume a "ballerina" stance with weight-bearing on the toes. Congenital flexure deformities usually resolve in the first few days of life. The best therapy is repeated intervals of brief exercise in a small paddock, physical therapy, and full limb bandages to relax the muscles in the forearm. If limited or no improvement is noted by three days post foaling, three-five grams of oxytetracycline is administered intravenously.5 It is repeated a second time after skipping a day if necessary. Toe extensions made from wood or aluminum taped on the feet may be useful.

Acquired flexural deformities occur during the first four months of life and generally involve the distal interphalangeal joint (Figure 4). These deformities are thought to be part of the developmental orthopedic disease (DOD) complex; however, pain initiating the pain withdrawal reflex is an important aspect of this condition. Any discomfort in the foot or lower limb will initiate the flexor withdrawal reflex which causes flexor muscle contraction and altered position of a joint. Feet trimmed too short with excess sole removed causing toe bruising is a common cause of acquired flexure deformities. The first clinical sign one may see during routine trimming is abnormal wear of the hoof wall at the toe. A closer look may reveal heat in the feet, increased digital pulse, pain on hoof testers, a prominent coronary band, and an upright hoof/pastern angle. Conservative treatment consisting of restricted exercise to decrease continued trauma, the judicious use of anti-inflammatory drugs to relieve pain, and the administration of oxytetracycline, which will cause muscle relaxation, can help restore the normal foot-pastern alignment.

Therapeutic trimming consisting of lowering the heels gently with a rasp and a composite toe extension can be applied to the dorsal hoof wall and the composite can be extended over the solar surface of the foot to protect that area from further bruising FLORIDAAEP |

@FLORIDA_VMA | The Practitioner  19

Figure 4. “Club foot” flexural deformities are acquired during the first four months of life and generally involve the distal interphalangeal joint.

Image courtesy of Dr. Steve O'Grady.

Figure 5. Therapeutic trimming consisting of lowering the heels with a rasp and applying a composite toe extension can be applied to the dorsal hoof wall and the composite can be extended over the solar surface of the foot to protect that area from further bruising.

Image courtesy of Dr. Steve O'Grady.

(Figure 5).3 The toe extension should act as an extension of the foot and it should place continuous tension on the musculotendonous unit. If this condition is allowed to persist, it will result in irreversible changes in the foot and joint capsule, requiring surgical intervention.

America, vol. 19:2. Philadelphia: W.B. Saunders, 2003; 501-517.

3. Hoof repair and glue-on shoe technology. Cheramie, H. S., O'Grady, S. E. In O'Grady, S.E., ed. The veterinary clinics of North America, vol. 19:2. Philadelphia: W.B. Saunders, 2003; 519-530.

4. Hunt, R. J., Management of Angular Limb Deformities. In Proceedings. Amer. Assoc of Equine Pract 2000; 46: 128-129.

5. Madison, J.B., Garber, J. L., Rice, B., et al., Effects of oxytetracycline on metacarpophalangeal and distal interphalangeal joint angles in newborn foals. J Am Vet Med Assoc 1994; 204: 240-249.

6. O’Grady, S.E., Farriery for the Young Horse. In Proceedings.

Amer. Assoc of Equine Pract Focus Meeting 2008.

7. Curtis, S., Farriery for the Young Horse: Flexural Deformities.

In Proceedings. World Equine Vet Assn 2011, 12:1-8.

If the acquired flexural deformity shows a marked broken forward hoof-pastern axis and the heels of the foot are raised off the ground and unable to bear weight, the hooves should be radiographed. If the radiograph reveals a flexural deformity involving the distal interphalangeal joint with a significant broken forward hoof-pastern axis signifying a shortening in the musculotendonous unit, surgical intervention in the form of an inferior check ligament desmotomy should be performed.

This is combined with lowering the heels of the foot from the widest part of the foot palmarly and applying a composite toe extension.

A more complex deformity is the metacarpophalangeal flexural deformity seen as knuckling forward at the fetlock. Once thought to be a shortening of the superficial digital musculotendinous unit, it is now known that the deep digital is also affected; occasionally, the suspensory ligament and metacarpophalangeal joint capsule are involved. Traditional and present day farriery treatment is to shoe with a raised heel and toe extension.6 The raised heel reduces tension on the flexor tendons (allowing the fetlock to descend), and the toe extension is to prevent further knuckling. It is the author’s opinion that this therapy should be initiated as soon as possible. In addition, restricted exercise to decrease continued trauma, and the judicious use of anti-inflammatory drugs to relieve pain, are essential parts of treatment. If this therapy fails, surgery will be necessary.

Unfortunately, surgery for this condition is much less successful than surgery for distal interphalangeal flexure deformity.

References

1. Greet, T. R. C., Managing Flexural and Angular Limb Deformities: The Newmarket Perspective. In Proceedings.

Amer. Assoc of Equine Pract 2000; 46: 130-136.

2. Foot management in the foal and weanling. Greet, T. R. C., Curtis, S. J. In O'Grady, S.E., ed. The veterinary clinics of North 20 The Practitioner

Tracy A. Turner, DVM, MS, DACVS, DACVSMR Dr. Tracy A. Turner received his DVM degree from Colorado State University in 1978 and interned at the University of Georgia. He completed a surgical residency and master’s degree at Purdue University.

He has served on the faculties of the University of Illinois, University of Florida, and the University of Minnesota. He joined Anoka Equine Clinic in Elk River, Minnesota, in 2004 and started his own practice in 2016 (Turner Equine Sports Medicine and Surgery), where he practices sports medicine, lameness, and surgery. Dr. Turner's primary areas of research interest have focused on equine lameness with interest in equine podiatry and thermography. He has spoken nationally and internationally on lameness topics. He has written more than 100 peer-reviewed manuscripts, more than 250 nonpeer-reviewed papers, and more than 30 book chapters on equine lameness, podiatry, and thermography. Dr. Turner is a diplomate of the American College of Veterinary Surgeons, a diplomate of the American College of Sports Medicine and Rehabilitation, and is a fellow of the American Academy of Thermology. He is an active member of the AVMA, the AAEP, the American Horse Council, and the Minnesota Horse Council.

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@FLORIDA_VMA | The Practitioner 21

TOOLS OF REHABILITATION ~ Part One ~

SARAH PLEVIN | BVMS, MRCVS, CVA, DABVP, DACVSMR, RCVS SPECIALIST The goal of veterinary rehabilitation is to restore the animal to its rates.2,3 Long periods of cold application have not been shown prior level of activity while preventing further injury. There are to negatively affect the horse, unlike in humans where negative numerous rehabilitation tools on the market today, all claiming a effects have been reported after 30-45 minutes.4 more expedient and successful recovery from injury. Anecdotal reports suggest beneficial effects from a variety of treatment Additionally, while periods of transient vasodilation (the 'hunting modalities: however, objective evidence to support them is largely reaction') caused by dilation of blood vessels in muscle tissue lacking. Extrapolation from the human field is commonplace have been observed in human limbs exposed to low temperatures, but is complicated by differences in skin thickness and anatomy this phenomenon has not been observed in experimental local between horses and humans. Consequently, therapeutic regimens cryotherapy applied to the equine distal limb, presumably due to are often recommended by the manufacturer of equipment the lack of skeletal muscle in that area.4 and not by equine-specific scientific research. This article will review some of the most frequently used equine rehabilitation modalities. For each, there will follow a summary of its use, its EQUINE-SPECIFIC SCIENCE mechanism of action, scientific evidence to support its use, and a Although cold therapy is a basic and extremely common treatment modality, few controlled studies investigating the optimal form of brief discussion about how we use it in our practice. cryotherapy in the distal limb of the horse exist.

HYDROTHERAPY

The most relevant clinical studies include comparison of wet interface (ice water immersion or ice boots) versus dry Hydrotherapy is any form of therapy utilizing water. Several interface application (cold pack or pneumatic sleeve) to the equine metacarpal area. A profound and superior sustained treatment modalities exist. reduction in deep tissue temperature has been reported with ice water immersion or ice boot application compared to either 1. COLD THERAPY (CRYOTHERAPY) dry interface technique, with a pneumatic sleeve being the only This is the therapeutic cooling of tissues. It is used for acute soft dry interface modality to achieve tissue temperatures within tissue injuries and is frequently a first line treatment. the therapeutic range in one study. Additionally, other studies have reported the combination of ice water and compression to be optimal at reducing tissue temperatures. These studies have MECHANISM OF ACTION also shown that cold pack-therapy alone is unable to effectively There are three main local effects reported when cold is applied cool soft tissue structures deeper than two to three centimeters, to any living tissue: regardless of application duration.2,5,6,7,8,9 1. Analgesia: due to a reduction in conduction velocity of peripheral nerves, increasing both the threshold for A commonly used commercial boot that uses ice water and stimulation and the refractory period after stimulation. intermittent compression is the Game Ready® system. However, 2. Hypometabolism: cold tissues have a reduced metabolism when ice and compression (in the form of ice bags and an elastic and therefore a reduced requirement for oxygen, glucose and bandage) were compared to the Game Ready® system in humans other metabolites. This phenomenon is thought to protect the ice and bandage model was found to be superior.5,10 Despite tissues on the periphery of an injury from secondary hypoxic this, the simplicity and ease of use of commercial systems make damage. In addition, hypometabolism "down regulates" pro them a very appealing and practical option. inflammatory cytokines and protease enzymatic activity.

3. Vasoconstriction: reducing the regional inflammatory 2. CONTRAST THERAPY response by reducing perfusion and edema.1 Contrast therapy is characterized by the repeated alternating applications of cold and heat. It is used to aid post-exercise Tissue temperatures ranging from 10-19°C have been recovery and to treat acute soft tissue injuries with the aim of reported to be necessary to maximize the physiologic effects increasing blood circulation through cyclic vasodilation and of vasoconstriction, pain relief and a decrease in metabolic vasoconstriction.

22 The Practitioner

Issue 4 • 2020

EQUINE-SPECIFIC SCIENCE A 2020 study by Colorado State University (CSU) investigated the ability of contrast therapy to heat and cool tissues.2 Four horses were investigated, and temperatures were assessed by thermistor placement deep to the superficial digital flexor tendons (SDFT) and deep to the deep digital flexor tendons (DDFT). The Vorteq system used was found to have the ability to heat and cool superficial tissues (to the depth of the DDFT) within the distal limb to the desired temperatures of greater than 40°C and less than 15°C. The equipment, however, was not able to consistently affect the temperatures of structures deep to the DDFT and its efficacy in diseased tissues was not investigated.2

3. COLD-WATER LEG SPA

A cold-water leg spa is a self-contained above ground unit that horses walk into. Salt water is pumped into the spa by jets of air. Manufacturers claim the jets of air create a massaging effect which stimulates tissues and relaxes horses. Additionally, aeration of water at low temperatures is known to significantly increase the concentration of oxygen and this, along with the advantage of the added osmotic effect of salt water, is thought to be the primary benefit of a leg spa. Spa water temperature is regulated at low temperatures of between 35-40°F (2-4 °C).

EQUINE-SPECIFIC SCIENCE A 2001 study of 27 horses with superficial digital flexor tendinopathies or suspensory ligament desmopathies, who were placed in a cold-water spa for 10 minutes three times per week, reported marked ultrasonographic improvement, with all but two horses returning successfully to training within six months.11 A reduction in paratendinous and tendinous fluid was considered the main advantage to healing generated by the spa treatments in this study. No controls and no specific information regarding rehabilitation were documented, making it a weaker study, but currently the only research available.11

HOW WE USE IT We use a cold-water leg spa to aid tendinopathy and desmopathy rehabilitation in the acute stages. We also have clients who use this modality as part of their routine daily/weekly schedule.

4. SWIMMING

Swimming is a common conditioning method for non-injured equine athletes and is routinely used as a rehabilitation tool for horses with musculoskeletal injuries. Swimming is considered a high intensity exercise, with heart rates of more than 200 beats per minute (bpm) being documented (similar to that of a horse at racing speeds). Such exercise, therefore, is not ideal for horses with orthopedic injuries, immediately post-surgery or after a long convalescent period. Swimming is also very taxing on the respiratory system, so should be introduced slowly and with care.12

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@FLORIDA_VMA | The Practitioner 23

The prime benefit of swimming is that it is a non-weight bearing cardiovascular activity. It does not activate all ground muscles and, therefore, should not replace normal training and should be seen only as an adjunct therapy, most useful in cases where ‘over ground’ activity is not possible. Professor Jean Marie Denoix also suggests caution if swimming horses with back conditions. He considers that vertebral overextension and stress to the cervicothoracic and lumbosacral junctions are possible when swimming, particularly if the horse is a poor swimmer.13 Additionally, others warn against swimming horses with thoracolumbar, sacroiliac, hip, stifle, and hock injuries citing extreme ranges of motion through the hip, stifle, and hock joints that occur as a result of the explosive nature of pelvic limb propulsion.14

EQUINE-SPECIFIC SCIENCE

Although swimming therapy is frequently used in rehabilitation programs there are few investigations into the benefits of it for equine patients.

Swim training programs have been shown to provide improvements in cardiovascular function and an increase in fast twitch high oxidative muscle fibers reflecting improved aerobic capacity.15 Additionally, swimming in combination with regular land-based exercise has been suggested to decrease vulnerability to locomotor disease and to promote an increase in performance capacity.16 One recent study, however, raised concerns about health implications in swimming horses. Ten racehorses (four thoroughbreds (TB) and six standardbreds (SB)) were examined during tethered swimming. Post inspiratory apnea (breath holding) was reported in all the horses during swimming exercise.

Authors cautioned against swimming horses with impaired upper respiratory tract function, but said more research was needed to determine the significance of the findings.17

EQUINE-SPECIFIC SCIENCE

A 2013 study showed the effect of water height on joint range of motion with water at varying depths promoting joint specific increases in range of motion. Results indicated the highest amount of flexion of forelimb joints (carpal and fetlock joints) was during the walking of horses in water at the level of the tarsal joint. For hindlimbs the greatest amount of tarsal flexion was found when water was at the level of the stifle.12 Results from this study encouraged clinicians to consider the effects of water depth when designing rehabilitation programs, especially if flexion or extension of a specific joint is the goal. For example, in horses with decreased range of motion of the fetlock joint, alternating exercise between two water depths (tarsal and fetlock) may be optimal. Water at the level of the tarsus would increase fetlock flexion while fetlock depth would increase fetlock extension.

Although varying water depths allow for varying levels of joint flexion, all water-treadmill exercise has the advantage over swimming in allowing for joint extension to some extent.

In a 2010 study, changes in stride parameters in horses walking on an aqua treadmill were investigated, again with differences documented depending on water height.18 Increasing water depth up to the level of the ulna led to an increase in stride length, a decrease in stride frequency and no effect on heart rate, with the inference that water treadmill exercise could be used to encourage hindlimb flexion as part of a rehabilitation program without increasing workload.18 Changes in water depth have additionally been documented to influence back movements. As water depth increases from hoof to shoulder level an increase in pelvic flexion and axial rotation, along with a decrease in lateral bending through the thoracolumbar region has been reported.22

5. UNDERWATER TREADMILL (UWT)

UWT (Figure 1) exercise has been shown to be predominantly an aerobic activity with heart rates of up to 120 beats/minute documented in trotting horses.18

The less intensive nature of UWT makes it more suitable for horses in the early stages of a controlled exercise program. One of its main advantages over swimming is its ability to allow for joint flexion and extension. Passive or active flexion and extension of injured limbs during early rehabilitation has been shown to be extremely important for good outcomes in humans recovering from orthopedic injury or surgery. As the same is thought to be true for horses, the ability of UWT to allow joint flexion and extension is of particular importance in a horse rehabilitating from a musculoskeletal injury. Aquatic exercise has resulted in improved limb function and range of motion in dogs, horses, and humans.12 19 20,21.

24 The Practitioner

Figure 1. A UWT is a self-contained above-ground, walk-in unit with a treadmill that fills with water to the desired height once the horse walks in. This modality can be considered a cardiovascular workout, albeit less extreme than swimming, especially regarding its effects on the respiratory system.

Image courtesy of Equine Performance Innovative Center.

Issue 4 • 2020

Furthermore, walking in water to the level of the stifle causes cranial extension and thoracolumbar flexion when compared with walking in ‘hoof depth’ water and these postural changes should be considered when developing rehabilitation programs for horses with back pathology.23

equipment for rehabilitation purposes is that they can get very fit extremely fast. This can be a problem regarding subsequently managing the horse’s restricted land-based activities i.e. horses want to do more than their injury allows for. For this reason, we put rehabilitating horses on the aquaciser for a maximum of twothree times per week as opposed to every day.

OTHER AQUATIC STUDIES

• Numerous human studies have demonstrated the benefits of aquatic exercise for musculoskeletal injuries. One study in 2010 indicated that humans undergoing aquatic exercise following total knee arthroplasty had reduced joint pain and stiffness and improved joint function for up to six months after discharge from the hospital.24 • A study by Colorado State University (CSU) demonstrated improvement in clinical signs of equine carpal osteoarthritis (OA) patients, with UWT having the ability to return the carpal joint to full motion. The improvement in clinical signs in the hydrotherapy group was also supported by evidence of disease modifying effects at a histologic level, with the UWT exercised group showing a reduction in joint capsule fibrosis and a decreased amount of inflammatory infiltrate present in the synovial membrane.25 • A second study by CSU determined that UWT exercise significantly improved postural stability in horses with surgically created carpal OA. Authors proposed that UWT activity increased afferent excitation of motor neurons for the muscles responsible for stabilizing the thoracic and pelvic limbs resulting in decreased postural sway. They suggested that aquatic therapy may be key to the management of joint disease.26

Figure 2. This hydrotherapy modality is a similar shape and size to a European walker. The horse walks down a gradual declining chute into the circular structure and once in the Aquaciser, they walk/jog freely in the water. The Aquaciser has the capacity to train up to six horses at one time. Ten different speed settings range training from a walk to the full extension of a trot.

Image courtesy of Dr. Sarah Plevin.

6. AQUACISER

In an Aquaciser (Figure 2 and 3), horses walk or jog in shoulder deep cold water (50-55°F) pushing the water and creating a current as they move. The cold water is a benefit to the horse as, already described, it helps to reduce pain and inflammation.

Additionally, because the horse is not suspended in the water, as it would be for swimming, full joint extension is achieved just as with the underwater treadmill devices. One of the main advantages of the Aquaciser over the aqua treadmill, however, is that it allows horses to recruit their limbs in an over-ground manner, unlike the treadmill, where the belt repositions the weight bearing limbs to a certain extent.

HOW WE USE IT

In our practice, it is used frequently for young horses that are on restricted land-based activities. Although most horses seem to enjoy this modality, a period of acclimatization is usually necessary. Limitations of this modality include the ability of horses to start and stop to some extent, unlike on a treadmill where they are forced to move at the programmed speed. This can easily be overcome, however, by tying their head to the gate in front of them. Another limitation for horses using this

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Figure 3. The Aquaciser offers a concussion free, intense aerobic workout. This method of training is ideal for older horses returning from a layoff or rehabilitating horses post injury.

Manufacturers claim a 70% reduction in concussion or impact compared to over-ground training.

Image courtesy of Dr. Sarah Plevin.

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LIGHT AMPLIFICATION

BY STIMULATED EMISSION OF RADIATION (LASER) THERAPY Laser devices emit light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

There are more than 5000 research papers looking into low-level laser therapy (LLLT) and around 50 looking into high-power lasers. Within this body of research, laser therapy has been reported to expedite the inflammatory process, decrease pain and promote tissue healing (promote fibroblast proliferation, promote synthesis of type 1 and 3 procollagen mRNA), expedite bone healing and help in revascularization of wounds amongst other things.

MECHANISM OF ACTION

It is thought that the mechanism of action is associated with the ability of cells to absorb light photons (energy) and transform that energy into ATP, reactive oxygen species and nitric oxide.

The increased ATP is suggested to promote homeostatic function of the cells, the reactive oxygen species are thought to increase immune function at certain levels, whilst nitric oxide has a dual function of increasing circulation and relieving pain.

window’ at red and near infrared wavelengths (600-1070nm).

Effective tissue penetration, in humans, is optimized in this range.

Wavelengths in the range 600-700 nm are used to treat superficial tissues, and longer wavelengths in the range 780-950 nm are used for deeper tissues.27 Wavelengths below 600 nm are strongly absorbed by the tissue chromophores, hemoglobin, and melanin, while those above 1000nm are readily absorbed by water. Protocols for treatment of wounds, tendinitis, desmitis, osteoarthritis (OA), and muscular soreness are available for horses—but are mainly extrapolated from human or in vitro studies.

SCIENCE

Whilst both in vivo and in vitro studies have reported the biologic effects of laser, including increased fibroblast and collagen production, improvement of collagen fiber alignment and increased angiogenesis, as well as decreased levels of pro inflammatory mediators such as PGE-2, in general, veterinary reports on the clinical effects are ambiguous.28,29,30 Studies in humans looking at low level laser have, however, been quite optimistic.

HUMAN STUDIES

LLLT in human osteoarthritis patients has been suggested to have a positive analgesic effect.31 Additionally, both red and infra-red LLLT have been shown to be effective at delaying the development of skeletal muscle fatigue and enhancing skeletal muscle performance.32

Furthermore, there is growing research on the effects of laser for wound healing and in non-equine studies, the histologic Different classes of laser: response to low-level laser therapy has indicated a reduction in 1. Low level: power < 500 mw. Wavelengths: 540nm-1060nm inflammation, edema, and an increase in collagen synthesis.33,34,35 2. High power, class IV: power > 500 mw. Wavelengths: 790 Although the research is notoriously conflicting and confusing at nm-980nm. Much of the energy from a high-power laser is times, a 2004 metanalysis evaluating the efficacy of laser to treat converted to heat and absorbed by water in the tissues. wounds in humans concluded that laser therapy is an effective 3. Multi Radiance laser—classed as low level but which use tool for promoting wound healing.36 combinations of multiple wavelengths to produce their effects. The synchronous use of high-power super-pulsed laser wavelength (905nm), ultra-bright infrared (875nm), EQUINE-SPECIFIC RESEARCH red (640nm) and blue (465nm) LEDs are suggested to A recent study in 2018 followed 150 sport horses diagnosed optimize the biological effects of the entire phototherapeutic with tendinopathy/desmopathy that were treated with a high window to accelerate healing and reduce pain. power (class IV) laser. A laser protocol was initiated two days • Multi Radiance lasers use super-pulsed diodes, which following diagnosis of injury and all horses were treated for 20 are more advanced and more expensive than continuous minutes a day for two consecutive weeks. All limbs were clipped lasers. It is important to note that a super-pulsed diode prior to application of laser therapy. Within two to six weeks after is not the same as just ‘pulsing’ a continuous wave laser. initiation of treatment, a significant improvement in lameness Super-pulsed diodes enable a Multi Radiance laser to and ultrasonographic scores was reported. Authors suggested safely super pulse up to 50,000 mw of power—more that laser therapy as a sole therapy might be clinically favorable. than most class IV lasers.

Although no negative effects from the use of high-power laser were documented, limitations of this study included the fact Light is measured in wavelengths and is expressed in units of that other treatment modalities were being used concurrently in nanometers (nm). Different wavelengths stimulate different many cases; there were no controls; and there was a disparity in chromophores that have various effects on tissues. In general, the rehabilitation protocols.37 longer the wavelength, the deeper the penetration into tissues.

The wavelength of light used for LLLT falls into a ‘therapeutic

26 The Practitioner

Issue 4 • 2020

Other areas of study for laser use in horses include the back, with one study using low-level laser documenting that 10 out of 14 horses with back pain showed clinical improvement after lasering specific acupuncture points.38 A 2020 study looking at the effects of low-level laser and chiropractic treatment on back pain concluded that laser therapy alone produced significant reductions in back pain and trunk stiffness in a population of quarter horses involved in active competition, whilst chiropractic therapy did not. The combination of chiropractic and laser provided some additive effects in treating back pain and trunk stiffness, supporting the concept that a multimodal approach is beneficial for rehabilitation.39 Importantly, some recent equine studies have addressed the question of ‘penetration depth’ related to laser competence.

Historically, in vitro studies have documented a level of laser efficacy that cannot be replicated in vivo. Lack of in vivo penetration, especially of low-level lasers, has been suggested to be the reason for this discrepancy. A 2016 equine cadaver study using a class IV laser documented that penetration of laser energy through equine skin samples was affected by the presence of hair and by the pigment of the skin. The darker the skin pigmentation the less the laser energy was able to penetrate the skin, with as little as 1.9% of emitted laser being reported to penetrate shaved black pigmented equine skin in that study. Data obtained supported clipping or shaving hair prior to laser treatment and advised that laser energy choices be based on skin pigmentation.

Figure 4. The main advantages of Multi Radiance lasers (e.g ACTIVet PRO™) are the greater penetration depths reported in unclipped skin, which includes most of the patients we see, and its excellent safety profile, which allows it to be used at FEI events, unlike a class IV laser.

Image courtesy of Dr. Sarah Plevin.

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Equally, that study reported that successful treatment of the deep digital flexor tendon and suspensory ligament should not be directed through the skin and the superficial digital flexor tendon but from medial or lateral aspects.40 A 2020 study looking at the penetration profiles of a class IV laser (LightForce™) versus a Multi Radiance laser unit (ACTIVet PRO™) also concluded that differences in penetration were attributed to skin color.

This study documented the ability of the Multi Radiance laser to provide greater penetration compared to the class IV laser in unclipped light and dark-skinned horses.

Often clipping is not acceptable especially in horses showing/ competing and/or if the laser is being used for general maintenance throughout the season. This study, therefore, provides practical evidence that a Multi Radiance laser unit may be the better and more practical clinical therapeutic choice for unclipped horses.41

HOW WE USE IT As Multi Radiance laser technology (Figure 4) has been validated in vivo, in vitro, in controlled laboratory studies, and in clinical trials, it is the laser technology we most commonly utilize in our practice.42,43,44 We commonly use it on acupuncture points for back conditions, for tendon and ligament injuries, as well as for wound management.

References

1. Kamioka, H., Tsutani, K., Okuizumi, H., Mutoh, Y., Ohta, M., Handa, S., ... & Honda, T. (2010). Effectiveness of aquatic exercise and balneotherapy: a summary of systematic reviews based on randomized controlled trials of water immersion therapies. Journal of epidemiology, 09102701130910270113.

2. Haussler, K. K., Wilde, S. R., Davis, M. S., Hess, A. M., & McIlwraith, C. W. (2020). Contrast therapy: Tissue heating and cooling properties within the equine distal limb. Equine Veterinary Journal.

3. Kaneps. (2016). Practical rehabilitation and physical therapy for the general equine practitioner. Vet Clin Equine, 32, 167180 4. Pollitt, C. C., & Van Eps, A. W. (2004). Prolonged, continuous distal limb cryotherapy in the horse. Equine veterinary journal, 36(3), 216-220.

5. Kraeutler, M. J., Reynolds, K. A., Long, C., & McCarty, E. C. (2015). Compressive cryotherapy versus ice—a prospective, randomized study on postoperative pain in patients undergoing arthroscopic rotator cuff repair or subacromial decompression. Journal of shoulder and elbow surgery, 24(6), 854-859.

6. Van Eps, A. W., & Orsini, J. A. (2016). A comparison of seven methods for continuous therapeutic cooling of the equine digit. Equine veterinary journal, 48(1), 120-124.

7. Kaneps, A. J. (2000). Tissue temperature response to hot and cold therapy in the metacarpal region of a horse.

In Proceedings (pp. 208-213). Profound and sustained reduction in deep tissue temp to iced water that was far superior to cold pack administration 8. Reesink, H. L., Divers, T. J., Bookbinder, L. C., Van Eps, A. W., Soderholm, L. V., Mohammed, H. O., & Cheetham, J. (2012).

Measurement of digital laminar and venous temperatures as a means of comparing three methods of topically applied FLORIDAAEP |

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cold treatment for digits of horses. American journal of veterinary research, 73(6), 860-866. Ice water immersion vs ice in plastic bags vs cold packs Reesink, H. L., Divers, T. J., van Eps, A. W., Soderholm, L. V., Wildenstein, M. J., & Cheetham, J. (2010, January).

Cryotherapy of the equine digit for the treatment of laminitis: assessment of a novel method by measuring digital venous temperature. In Proceedings. ACVS Surgical Symposium E (Vol. 49).

Hawkins, J., Shurtz, J., & Spears, C. (2012). Traditional cryotherapy treatments are more effective than game ready on medium setting at decreasing sinus tarsi tissue temperatures in uninjured subjects. J Athl Enhancement, 1(2), 1-5.

Hunt, E. R. (2001). Response of twenty-seven horses with lower leg injuries to cold spa bath hydrotherapy. Journal of Equine Veterinary Science, 21(4), 188-193.

Mendez-Angulo, J. L., Firshman, A. M., Groschen, D. M., Kieffer, P. J., & Trumble, T. N. (2013). Effect of water depth on amount of flexion and extension of joints of the distal aspects of the limbs in healthy horses walking on an underwater treadmill. American journal of veterinary research, 74(4), 557-566.

Bromiley, M. (2013). Equine injury, therapy, and rehabilitation. John Wiley & Sons.

King, M. R. (2016). Principles and application of hydrotherapy for equine athletes. Veterinary Clinics: Equine Practice, 32(1), 115-126.

Misumi, K., Sakamoto, H., & Shimizu, R. (1995). Changes in skeletal muscle composition in response to swimming training for young horses. Journal of Veterinary Medical Science, 57(5), 959-961.

Misumi, K., Sakamoto, H., & Shimizu, R. (1994). The validity of swimming training for two-year-old thoroughbreds.

Journal of Veterinary Medical Science, 56(2), 217-222.

Jones, S., Franklin, S., Martin, C., & Steel, C. (2020).

Complete upper airway collapse and apnoea during tethered swimming in horses. Equine Veterinary Journal, 52(3), 352358.

Scott, R., Nankervis, K., Stringer, C., Westcott, K., & Marlin, D. (2010). The effect of water height on stride frequency, stride length and heart rate during water treadmill exercise.

Equine Veterinary Journal, 42, 662-664.

Valtonen, A., Pöyhönen, T., Sipilä, S., & Heinonen, A. (2010).

Effects of aquatic resistance training on mobility limitation and lower-limb impairments after knee replacement.

Archives of physical medicine and rehabilitation, 91(6), 833839.

Marsolais, G. S., McLean, S., Derrick, T., & Conzemius, M. G. (2003). Kinematic analysis of the hind limb during swimming and walking in healthy dogs and dogs with surgically corrected cranial cruciate ligament rupture.

Journal of the American Veterinary Medical Association, 222(6), 739-743.

Brady, B., Redfern, J., Macdougal, G., & Williams, J. (2008).

The addition of aquatic therapy to rehabilitation following surgical rotator cuff repair: a feasibility study. Physiotherapy Research International, 13(3), 153-161.

Mooij, M. J. W., Jans, W., Den Heijer, G. J. L., De Pater, M., & Back, W. (2013). Biomechanical responses of the back of riding horses to water treadmill exercise. The Veterinary Journal, 198, e120-e123.

Nankervis, K. J., Finney, P., & Launder, L. (2016). Water depth modifies back kinematics of horses during water

28 The Practitioner

treadmill exercise. Equine veterinary journal, 48(6), 732-736.

24. Giaquinto, S., Ciotola, E., Dall’Armi, V., & Margutti, F. (2010).

Hydrotherapy after total knee arthroplasty. A follow-up study. Archives of gerontology and geriatrics, 51(1), 59-63.

25. King, M. R., Haussler, K. K., Kawcak, C. E., McIlwraith, C. W., Reiser, R. F., Frisbie, D. D., & Werpy, N. M. (2017).

Biomechanical and histologic evaluation of the effects of underwater treadmill exercise on horses with experimentally induced osteoarthritis of the middle carpal joint. American Journal of Veterinary Research, 78(5), 558-569.

26. King, M. R., Haussler, K. K., Kawcak, C. E., McIlwraith, C. W., & Reiser II, R. F. (2013). Effect of underwater treadmill exercise on postural sway in horses with experimentally induced carpal joint osteoarthritis. American journal of veterinary research, 74(7), 971-982.

27. Chung, H., Dai, T., Sharma, S. K., Huang, Y. Y., Carroll, J. D., & Hamblin, M. R. (2012). The nuts and bolts of lowlevel laser (light) therapy. Annals of biomedical engineering, 40(2), 516-533.

28. Petersen, S. L., Botes, C., Olivier, A., & Guthrie, A. J. (1999).

The effect of low-level laser therapy (LLLT) on wound healing in horses. Equine veterinary journal, 31(3), 228-231.

29. Kaneps, A. J., Hultgren, B. D., Riebold, T. W., & Shires, G. M. (1984). Laser therapy in the horse: histopathologic response.

American journal of veterinary research, 45(3), 581.

30. Husby, K. A. (2016). In vitro evaluation of therapeutic laser treatment on equine tendon fibroblasts.

31. Alghadir, A., Omar, M. T. A., Al-Askar, A. B., & Al-Muteri, N. K. (2014). Effect of low-level laser therapy in patients with chronic knee osteoarthritis: a single-blinded randomized clinical study. Lasers in medical science, 29(2), 749-755.

32. de Almeida, P., Lopes-Martins, R. Á. B., De Marchi, T., Tomazoni, S. S., Albertini, R., Corrêa, J. C. F., ... & Junior, E. C. P. L. (2012). Red (660 nm) and infrared (830 nm) lowlevel laser therapy in skeletal muscle fatigue in humans: what is better? Lasers in medical science, 27(2), 453-458.

33. Prabhu, V., Rao, S. B., Chandra, S., Kumar, P., Rao, L., Guddattu, V., ... & Mahato, K. K. (2012). Spectroscopic and histological evaluation of wound healing progression following Low Level Laser Therapy (LLLT). Journal of biophotonics, 5(2), 168-184.

34. Hopkins, J. T., McLoda, T. A., Seegmiller, J. G., & Baxter, G. D. (2004). Low-level laser therapy facilitates superficial wound healing in humans: a triple-blind, sham-controlled study. Journal of athletic training, 39(3), 223.

35. Posten, W., Wrone, D. A., Dover, J. S., Arndt, K. A., Silapunt, S., & Alam, M. (2005). Low‐level laser therapy for wound healing: mechanism and efficacy. Dermatologic surgery, 31(3), 334-340.

36. Woodruff, L. D., Bounkeo, J. M., Brannon, W. M., Dawes, K. S., Barham, C. D., Waddell, D. L., & Enwemeka, C. S. (2004).

The efficacy of laser therapy in wound repair: a meta-analysis of the literature. Photomedicine and laser surgery, 22(3), 241-247.

37. Pluim, M., Martens, A., Vanderperren, K., Sarrazin, S., Koene, M., Luciani, A., ... & Delesalle, C. (2018). Shortand long-term follow-up of 150 sports horses diagnosed with tendinopathy or desmopathy by ultrasonographic examination and treated with high-power laser therapy.

Research in veterinary science, 119, 232.

38. KLIDE, A. M. (1987). Treatment of chronic back pain in horses stimulation of acupuncture points with a low powered infrared laser. Veterinary Surgery, 16(1), 106-110.

Issue 4 • 2020

39. Haussler, K. K., Manchon, P. T., Donnell, J. R., & Frisbie, D. D. (2020). Effects of Low-Level Laser Therapy and Chiropractic Care on Back Pain in Quarter Horses. Journal of Equine Veterinary Science, 86, 102891.

40. Duesterdieck-Zellmer, K. F., Larson, M. K., Plant, T. K., Sundholm-Tepper, A., & Payton, M. E. (2016). Ex vivo penetration of low-level laser light through equine skin and flexor tendons. American journal of veterinary research, 77(9), 991-999.

41. Luna, S. P. L., Schoen, A., Trindade, P. H. E., & da Rocha, P. B. (2020). Penetration Profiles of a Class IV Therapeutic Laser and a Photobiomodulation Therapy Device in Equine Skin.

Journal of Equine Veterinary Science, 85, 102846.

42. dos Santos GrandinĂŠtti, V., Miranda, E. F., Johnson, D. S., de Paiva, P. R. V., Tomazoni, S. S., Vanin, A. A., ... & Leal-Junior, E. C. P. (2015). The thermal impact of phototherapy with concurrent super-pulsed lasers and red and infrared LEDs on human skin. Lasers in medical science, 30(5), 1575-1581.

43. Antonialli, F. C., De Marchi, T., Tomazoni, S. S., Vanin, A. A., dos Santos Grandinetti, V., de Paiva, P. R. V., ... & Leal-Junior, E. C. P. (2014). Phototherapy in skeletal muscle performance and recovery after exercise: effect of combination of superpulsed laser and light-emitting diodes. Lasers in medical science, 29(6), 1967-1976.

44. Leal-Junior, E. C. P., Johnson, D. S., Saltmarche, A., & Demchak, T. (2014). Adjunctive use of combination of super-pulsed laser and light-emitting diodes phototherapy on nonspecific knee pain: double-blinded randomized placebo-controlled trial. Lasers in medical science, 29(6), 1839-1847.

CLASS-LEADING EQUINE WELLNESS SOLUTIONS Zoetis offers the vital products your practice needs from vaccines to dewormer products.

Sarah Plevin, BVMS, MRCVS, CVA, DABVP, DACVSMR, RCVS specialist Dr. Sarah Plevin is a sports medicine specialist and partner at Florida Equine Ve t e r i n a r y A s s o c i a t e s .

Originally from the United Kingdom, she graduated from Glasgow Veterinary School in Scotland. After, completing a surgical internship in Ocala, Florida, she went into general practice for a couple of years before undertaking a lameness fellowship and then pursing specialist qualifications. She is double boarded with the American Association of Veterinary Practitioners and the American College of Veterinary Sports Medicine and Rehabilitation. Dr. Plevin has also attained status as an equine sports medicine specialist from the Royal College of Veterinary Surgeons and is certified in veterinary acupuncture. Currently, Dr. Plevin devotes most of her time to clinical research and leads the research department at FEVA, where her focus is on preventing injuries in the juvenile TB racehorse. She has presented her work both nationally and internationally. Outside of work, Dr. Plevin is a keen swimmer and enjoys all outdoor activities. She is married with three young children and enjoys traveling extensively throughout the world with her family.

All trademarks are the property of Zoetis Services LLC or a related company or a licensor unless otherwise noted. Š 2019 Zoetis Services LLC. All rights reserved. GEQ-00533

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