The Modern Equine Vet January 2015 by The Modern Equine Vet

The Modern

Equine Vet www.modernequinevet.com

Vol 5 Issue 1 2015

Managing foal

rejection

Can nerve stimulator help headshaking? How to repair eyelid lacerations Tiludronate for navicular syndrome

Table of Contents

Cover story:

6 Managing foal rejection

Cover photo Shutterstock/eastern light photography

Colic

Changes in pregnant mare's fecal microbiota precedes colic.................................. 4 CNS

Can a nerve stimulator help headshaking?.................................................................... 5 Ophthalmology

How to repair eyelid lacerations.......................................................................................11 orthopedics

Tiludronate may offer solution for navicular syndrome..........................................14 Technician Update

Rhodococcus equi: ubiquitous but deadly...................................18 News

Lonestar tick may harbor unusual virus..............................................10 O-scan MRI installed in US veterinary center.........................19 Video: Vets examine benefits of abdominal bandages............. 10 advertisers MERCK Animal Health................................................. 3 CEVA Animal Health.................................................... 9

AAEVT............................................................................17

The Modern

Equine Vet Sales: Robin Geller • newbucks99@yahoo.com Editor: Marie Rosenthal • mrosenthal@percybo.com Art Director: Jennifer Barlow • jbarlow@percybo.com contributing writerS: Paul Basillo • Kathleen Olge COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers percybo media  publishing

Issue 1/2015 | ModernEquineVet.com

LEGAL DISCLAIMER: The content in this digital issue is for general informational purposes only. PercyBo Publishing Media LLC makes no representations or warranties of any kind about the completeness, accuracy, timeliness, reliability or suitability of any of the information, including content or advertisements, contained in any of its digital content and expressly disclaims liability of any errors or omissions that may be presented within its content. PercyBo Publishing Media LLC reserves the right to alter or correct any content without any obligations. Furthermore, PercyBo disclaims any and all liability for any direct, indirect, or other damages arising from the use or misuse of the information presented in its digital content. The views expressed in its digital content are those of sources and authors and do not necessarily reflect the opinion or policy of PercyBo. The content is for veterinary professionals. ALL RIGHTS RESERVED. Reproduction in whole or in part without permission is prohibited.

When everything is at stake, trust Regu-Mate

Properly managing your mare’s hormones is critical, from the broodmare to the performance horse. Regu-Mate Over 200 clinical trials to determine efficacy, duration and safety Over 30 years of practical use in the field by veterinarians Over 20 million doses sold to veterinarians, trainers and horse owners

Tried and tested – trust the original. Trust Regu-Mate. regu-mate.com

We’re for the Horse™

Talk to your veterinarian about proper use and safe handling of Regu-Mate. Avoid skin contact. Always wear protective gloves when administering Regu-Mate. This product is contraindicated for use in mares with a previous or current history of uterine inflammation. Pregnant women, or women who suspect they are pregnant, should not handle this product. For complete product information, see accompanying product insert. 2 Giralda Farms • Madison, NJ 07940 • merck-animal-health-usa.com • 800-521-5767 Copyright © 2013 Intervet Inc., d/b/a Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved. Photography: Vince Cook. 50034 7/13 EQ-BIO-1215-AD-BR

ModernEquineVet.com | Issue 1/2015

Colic

Regu-Mate® (altrenogest) Solution 0.22% (2.2 mg/mL) CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. DESCRIPTION: Regu-Mate® (altrenogest) Solution 0.22% contains the active synthetic progestin, altrenogest. The chemical name is 17α-allyl-17ß-hydroxyestra-4,9,11-trien-3-one. The CAS Registry Number is 850-52-2. The chemical structure is: Each mL of Regu-Mate® (altrenogest) Solution 0.22% contains 2.2 mg of altrenogest in an oil solution.

INDICATIONS: Regu-Mate® (altrenogest) Solution 0.22% is indicated to suppress estrus in mares. Suppression of estrus allows for a predictable occurrence of estrus following drug withdrawal. This facilitates the attainment of regular cyclicity during the transition from winter anestrus to the physiological breeding season. Suppression of estrus will also facilitate management of prolonged estrus conditions. Suppression of estrus may be used to facilitate scheduled breeding during the physiological breeding season. CONTRAINDICATIONS: Regu-Mate® (altrenogest) Solution 0.22% is contraindicated for use in mares having a previous or current history of uterine inflammation (i.e., acute, subacute, or chronic endometritis). Natural or synthetic gestagen therapy may exacerbate existing low-grade or “smoldering” uterine inflammation into a fulminating uterine infection in some instances. PRECAUTIONS: Various synthetic progestins, including altrenogest, when administered to rats during the embryogenic stage of pregnancy at doses manyfold greater than the recommended equine dose caused fetal anomalies, specifically masculinization of the female genitalia. DOSAGE AND ADMINISTRATION: While wearing protective gloves, remove shipping cap and seal; replace with enclosed plastic dispensing cap. Remove cover from bottle dispensing tip and connect luer lock syringe (without needle). Draw out appropriate volume of Regu-Mate solution. (Note: Do not remove syringe while bottle is inverted as spillage may result.) Detach syringe and administer solution orally at the rate of 1 mL per 110 pounds body weight (0.044 mg/kg) once daily for 15 consecutive days. Administer solution directly on the base of the mare’s tongue or on the mare’s usual grain ration. Replace cover on bottle dispensing tip to prevent leakage. Excessive use of a syringe may cause the syringe to stick; therefore, replace syringe as necessary. WHICH MARES WILL RESPOND TO REGU-MATE® (altrenogest) SOLUTION 0.22%: Extensive clinical trials have demonstrated that estrus will be suppressed in approximately 95% of the mares within three days; however, the post-treatment response depended on the level of ovarian activity when treatment was initiated. Estrus in mares exhibiting regular estrus cycles during the breeding season will be suppressed during treatment; these mares return to estrus four to five days following treatment and continue to cycle normally. Mares in winter anestrus with small follicles continued in anestrus and failed to exhibit normal estrus following withdrawal. Response in mares in the transition phase between winter anestrus and the summer breeding season depended on the degree of follicular activity. Mares with inactive ovaries and small follicles failed to respond with normal cycles post-treatment, whereas a higher proportion of mares with ovarian follicles 20 mm or greater in diameter exhibited normal estrus cycles posttreatment. Regu-Mate® (altrenogest) Solution 0.22% was very effective for suppressing the prolonged estrus behavior frequently observed in mares during the transition period (February, March and April). In addition, a high proportion of these mares responded with regular estrus cycles post-treatment. SPECIFIC USES FOR REGU-MATE® (altrenogest) SOLUTION 0.22%: SUPPRESSION OF ESTRUS TO: 1. Facilitate attainment of regular cycles during the transition period from winter anestrus to the physiological breeding season. To facilitate attainment of regular cycles during the transition phase, mares should be examined to determine the degree of ovarian activity. Estrus in mares with inactive ovaries (no follicles greater than 20 mm in diameter) will be suppressed but these mares may not begin regular cycles following treatment. However, mares with active ovaries (follicles greater than 20 mm in diameter) frequently respond with regular post-treatment estrus cycles. 2. Facilitate management of the mare exhibiting prolonged DOSAGE CHART: estrus during the transition period. Estrus will be suppressed in mares exhibiting prolonged behavioral estrus either early Approximate Weight Dose or late during the transition period. Again, the posttreatment in Pounds in mL response depends on the level of ovarian activity. The 770 7 mares with greater ovarian activity initiate regular cycles 880 8 and conceive sooner than the inactive mares. Regu-Mate® 990 9 (altrenogest) Solution 0.22% may be administered early in 1100 10 the transition period to suppress estrus in mares with inactive 1210 11 ovaries to aid in the management of these mares or to mares 1320 12 later in the transition period with active ovaries to prepare and schedule the mare for breeding. 3. Permit scheduled breeding of mares during the physiological breeding season. To permit scheduled breeding, mares which are regularly cycling or which have active ovarian function should be given Regu-Mate® (altrenogest) Solution 0.22% daily for 15 consecutive days beginning 20 days before the date of the planned estrus. Ovulation will occur 5 to 7 days following the onset of estrus as expected for nontreated mares. Breeding should follow usual procedures for mares in estrus. Mares may be regulated and scheduled either individually or in groups. ADDITIONAL INFORMATION: A 3-year well controlled reproductive safety study was conducted in 27 pregnant mares, and compared with 24 untreated control mares. Treated mares received 2 mL Regu-Mate® (altrenogest) Solution 0.22% /110 lb body weight (2x dosage recommended for estrus suppression) from day 20 to day 325 of gestation. This study provided the following data: 1. In filly offspring (all ages) of treated mares, clitoral size was increased. 2. Filly offspring from treated mares had shorter interval from Feb. 1 to first ovulation than fillies from their untreated mare counterparts. 3. There were no significant differences in reproductive performance between treated and untreated animals (mares & their respective offspring) measuring the following parameters: • •

• • • • • • •

interval from Feb. 1 to first ovulation, in mares only. mean interovulatory interval from first to second cycle and second to third cycle, mares only. follicle size, mares only. at 50 days gestation, pregnancy rate in treated mares was 81.8% (9/11) and untreated mares was 100% (4/4). after 3 cycles, 11/12 treated mares were pregnant (91.7%) and 4/4 untreated mares were pregnant (100%). colt offspring of treated and control mares reached puberty at approximately the same age (82 & 84 weeks respectively). stallion offspring from treated and control mares showed no differences in seminal volume, spermatozoal concentration, spermatozoal motility, and total sperm per ejaculate. stallion offspring from treated and control mares showed no difference in sexual behavior. testicular characteristics (scrotal width, testis weight, parenchymal weight, epididymal weight and height, testicular height, width & length) were the same between stallion offspring of treated and control mares.

REFERENCES: Shoemaker, C.F., E.L. Squires, and R.K. Shideler. 1989.Safety of Altrenogest in Pregnant Mares and on Health and Development of Offspring. Eq. Vet. Sci. (9); No. 2: 69-72. Squires, E.L., R.K. Shideler, and A.O. McKinnon. 1989.Reproductive Performance of Offspring from Mares Administered Altrenogest During Gestation. Eq. Vet. Sci. (9); No. 2: 73-76. WARNING: Do not use in horses intended for food. HUMAN WARNINGS: Skin contact must be avoided as Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed through unbroken skin. Protective gloves must be worn by all persons handling this product. Pregnant women or women who suspect they are pregnant should not handle Regu-Mate® (altrenogest) Solution 0.22%. Women of child bearing age should exercise extreme caution when handling this product. Accidental absorption could lead to a disruption of the menstrual cycle or prolongation of pregnancy. Direct contact with the skin should therefore be avoided. Accidental spillage on the skin should be washed off immediately with soap and water. INFORMATION FOR HANDLERS: WARNING: Regu-Mate® (altrenogest) Solution 0.22% is readily absorbed by the skin. Skin contact must be avoided; protective gloves must be worn when handling this product. Effects of Overexposure: There has been no human use of this specific product. The information contained in this section is extrapolated from data available on other products of the same pharmacological class that have been used in humans. Effects anticipated are due to the progestational activity of altrenogest. Acute effects after a single exposure are possible; however, continued daily exposure has the potential for more untoward effects such as disruption of the menstrual cycle, uterine or abdominal cramping, increased or decreased uterine bleeding, prolongation of pregnancy and headaches. The oil base may also cause complications if swallowed. In addition, the list of people who should not handle this product (see below) is based upon the known effects of progestins used in humans on a chronic basis. PEOPLE WHO SHOULD NOT HANDLE THIS PRODUCT. 1. 2. 3. 4. 5. 6. 7. 8.

Women who are or suspect they are pregnant. Anyone with thrombophlebitis or thromboembolic disorders or with a history of these events. Anyone with cerebral-vascular or coronary artery disease. Women with known or suspected carcinoma of the breast. People with known or suspected estrogen-dependent neoplasia. Women with undiagnosed vaginal bleeding. People with benign or malignant tumors which developed during the use of oral contraceptives or other estrogen-containing products. Anyone with liver dysfunction or disease.

ACCIDENTAL EXPOSURE: Altrenogest is readily absorbed from contact with the skin. In addition, this oil based product can penetrate porous gloves. Altrenogest should not penetrate intact rubber or impervious gloves; however, if there is leakage (i.e., pinhole, spillage, etc.), the contaminated area covered by such occlusive materials may have increased absorption. The following measures are recommended in case of accidental exposure. Skin Exposure: Wash immediately with soap and water. Eye Exposure: Immediately flush with plenty of water for 15 minutes. Get medical attention. If Swallowed: Do not induce vomiting. Regu-Mate® (altrenogest) Solution 0.22% contains an oil. Call a physician. Vomiting should be supervised by a physician because of possible pulmonary damage via aspiration of the oil base. If possible, bring the container and labeling to the physician.

Changes in pregnant mare's fecal microbiota precedes colic, but foaling may not be cause A recent study found consistent changes in fecal microbiota of mares after foaling, which preceded episodes of colic. This could lead to identification of higher risk mares and manipulation of the microbiota to reduce the risk of colic. “Colic is an important problem in post partum mares, and large colon volvulus, one of the most severe forms of colic is over represented in this group,” the researchers wrote in the Equine Veterinary Journal. Recent studies have explored the complex nature of the equine fecal microbiota. In this multicenter study, the researchers wanted to know if there were consistent changes in the microbiota preceding an episode of post partum colic. The researchers collected pre and post partum fecal samples from pregnant and non pregnant mares on three Kentucky farms. All of the mares were healthy and up to date on current vaccinations and deworming status. Farm managers and veterinarians provided information about feeding, management, foaling dates and colic episodes. The feeding and housing management was different for all three farms, but all mares had free access to hay and water and received concentrates two or three times a day. The concentrate was different on each farm, but feeding practices were consistent among them. After foaling, the mares had access to pasture. Initially, 221 mares were enrolled and 24 (11%) developed post partum colic. Fecal samples were collected prior to the colic in 19 of the 24 horses that developed colic, and 13 were available for analysis. They compared them with 13 pregnant mares and five nonpregnant mares, who acted as controls.

For more information: Weese JS, Holcombe SJ, Embertson RM, et al. Changes in the faecal microbiota of mares precede the development of post partum colic. Equine Veterinary Journal 2014; doi: 10.111/evj.12361

CAUTION: For oral use in horses only. Keep this and all medication out of the reach of children. Store at or below 25°C (77°F). NADA# 131-310, Approved by FDA.

http://onlinelibrary.wiley.com/doi/10.1111/evj.12361/pdf

HOW SUPPLIED: Regu-Mate® (altrenogest) Solution 0.22% (2.2 mg/mL). Each mL contains 2.2 mg altrenogest in an oil solution. Available in 1000 mL plastic bottles. * US Patents 3,453,267; 3,478,067; 3,484,462 Manufactured by: DPT Laboratories, San Antonio, TX 78215 Distributed by: Intervet Inc., Millsboro, DE 19966

Pre and post foaling fecal samples were analyzed by next generation sequencing following DNA extraction. “The fecal microbiota of mares consisted of a rich and diverse microbial population containing a large number of phyla, consistent with other studies of the equine fecal microbiota,” the researchers wrote. The fecal microbiota during late pregnancy was different from that of non-pregnant control mares, but only in the microbial community membership and structure, rather than differences in phyla. There was no significant impact of foaling on the fecal microbiome; however, fecal samples collected prior to colic episodes had a significantly higher relative abundance of Proteobacteria. Samples with a relative abundance of Firmicutes of <50% all preceded a colic episode. “It was interesting that more changes were noted in samples collected within 10 days of the onset of colic compared with a larger subset of samples that preceded colic, but by a broader time frame (mean 17.5) days,” the researchers wrote, suggesting that fecal changes occur within a short time before the onset of colic and could be a predisposing factor for the development of colic. MeV

Issue 1/2015 | ModernEquineVet.com

Shutterstock/ Tupungato

ACTIONS: Regu-Mate® (altrenogest) Solution 0.22% produces a progestational effect in mares.

CNS

Can a nerve stimulator help horse's headshaking? Headshaking syndrome occurs when a horse shakes or jerks its head uncontrollably for no apparent reason. There are no consistently safe and effective treatments for headshaking in horses, which can leave affected horses impossible to ride and dangerous to handle, resulting in euthanasia. However, a therapy that is used to manage human neuropathic pain may help reduce the signs of equine headshaking caused by equine neuropathic facial pain syndrome. “Headshaking in horses is a major welfare issue and can be a significant cause of distress,” said Veronica Roberts, MA(Oxon), MA, VetMB(Cantab) senior clinical fellow in equine medicine in the University of Bristol School of Veterinary Sciences in the United Kingdom. Headshaking usually occurs in adult horses, and the syndrome appears to be more common among Geldings. Common triggers include bright light, heat, season and exercise. In fact, over-conditioned horses may be at higher risk. Normally a battery of diagnostic tests are done to rule out other conditions before diagnosing headshaking, including a physical exam that focuses on the head, neck and possible pain sources, blood work, endoscopy of the upper airways and guttural pouches; radiographs of the skull; and occasionally otoscopy.

Minimizing shaking

There are striking clinical similarities between human facial pain syndromes, such as trigeminal neuralgia, and headshaking in horses. A new study has found a treatment called percutaneous electrical nerve stimulation (PENS) may help. The study led by researchers from the University of Bristol’s School of Veterinary Sciences, working with the neurology team at Southmead Hospital Bristol, wanted to find out if PENS therapy, developed by Algotec Research and Development Ltd, is safe, effective and sustainable for the management of trigeminalmediated headshaking in horses. Seven horses diagnosed with trigeminal-mediated headshaking were recruited to the trial. All procedures were carried out in sedated horses with a needle-prick sized area of skin desensitized with lo-

cal anaesthetic to help probe insertion. A disposable PENS probe was placed just beneath the skin adjacent to the nerve under ultrasonographic guidance. The nerve was stimulated for 25 minutes following a protocol of alternating frequencies and a perception threshold based on human clinical data. The probe was removed and the procedure repeated on the other side. Three or four treatments were used during the protocol, with treatments being repeated when signs of headshaking recurred. All horses tolerated the procedure. Three horses developed a hematoma at the site on one occasion and two had increased clinical signs for up to three days following first treatment. Six horses responded well after the first treatment and returned to ridden work at the same level as before headshaking began. Five horses continued to respond to further treatment, according to the results published in the Equine Veterinary Journal. “Although it is clear that further work is required, including increasing the number of cases and refining the treatment procedures, the study shows that PENS therapy should be the first-line treatment for trigeminal-mediated headshakers, which have failed to respond to conservative treatment, such as nose-nets,” Ms. Roberts said. MeV

At present there are no consistently safe and effective methods for the treatment of headshaking in horses. The condition often leaves affected horses impossible to ride and dangerous to handle, and can result in euthanasia.

For more information: Roberts VLH, Patel NK, Tremaine WH. Neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminalmediated headshaking; a safe procedure resulting in medium term remission in five of seven horses. Equine Veterinary Journal 2014; doi: 10.1111/evj.12394. http://onlinelibrary.wiley.com/doi/10.1111/evj.12394/abstract;jsessionid=101FAA2F429B4E719597A97249473268.f01t04 ModernEquineVet.com | Issue 1/2015

cover story

Managing

Foal Rejection Not every mare is a natural

mother, although foal rejection is a relatively rare occurrence in general practice. If the mare is rejecting her foal and not allowing it to nurse or worse, trying to hurt the young horse, there are steps that caregivers can take to help improve the relationship. Normal maternal behavior is initiated and developed by numerous factors, including sensory and tactile stimuli, said Charles F. Scoggin,

B y Using a twitch to keep mom in check while foal nurses.

Issue 1/2015 | ModernEquineVet.com

DVM, MS, DACT, a practitioner at Claiborne Farm in Paris, Ky. These stimuli trigger various physiologic events within the mare that are mediated primarily through several hormones, such as oxytocin. “Much as in other species, some mares are just better mothers than others,” he explained at the 60th Annual AAEP Convention in Salt Lake City. “This may be due to age, experience, temperament, or a ‘je ne sais quoi’ that has yet to be

P a u l

determined but should not be discounted.” Many qualities of abnormal maternal behavior have been described in the literature, but the two most common signs seen in foal rejection can be categorized as either aggression or avoidance; in some cases, the mare will display a combination of the two. “Risk factors that can lead to foal rejection include age and parity,” Dr. Scoggin said. “Young, maiden

B a s i l i o

mares appear to be at a greater risk than older, multiparous mares. Certain disease processes that cause poor lactation or somatic or visceral pain can all lead to foal rejection.” Risk factors in the foal include underlying disease that makes them less likely to nurse, such as hypoxic ischemic encephalopathy. Dimethyl sulfoxide (DMSO) and other medications that can cover up an animal’s natural odor can also lead to rejection.

Photos by veterinary technician, Mary Stewart White, BS

Management

In cases of foal rejection, immediate triage is indicated. “Safety is paramount,” Dr. Scoggin noted. “Measures should be taken to reduce the risk of injury to the horses and the humans.” Because the foal has likely been unable or unwilling to nurse, it is important to ensure adequate passive transfer. If necessary, the foal should be given at least one pint of good quality colostrum through a nasogastric tube; IV plasma and additional supportive care. Preemptive treatment with antimicrobials and IV fluids should be considered to stave off sepsis and dehydration. Physical restraint is often the first line of treatment for foal rejection. Dr. Scoggin typically starts with in-hand restraint in cases where the mare is attempting to avoid the foal but is not showing signs of aggression. Dr. Scoggin tends to favor a lip chain over a nose twitch when more severe restraint is indicated. “The nose twitch often causes the mare to stand still and can act as a distraction as the foal attempts to nurse, but with a lip chain I can more readily adjust the pressure on the mare,” he said. “If she is calm and allows the foal to nurse, then I only need minimal pressure. If the mare gets unruly or aggressive, a quick snatch can quickly reprimand her.” At Dr. Scoggin’s farm, staff creat-

ModernEquineVet.com | Issue 1/2015

cover story

ed a padded barricade that can safely restrict the mare’s movements. A wooden door at udder level allows the foal controlled access to the teat. “In cases where we have to leave the mare and foal unattended, this setup offers added protection for the foal,” he explained. “If the mare has to be left in the barricade for a prolonged time, it is important to take her out to allow her to move around from time to time to avoid stiffness or distal limb edema.” Behavior modification using positive reinforcement, such as offering encouragement in a soothing voice, gently rubbing the mare on the neck and offering peppermints, grain or carrots as a reward for good behavior, is often used in tandem with physical restraint. If negative reinforcement is needed, Dr. Scoggin recommended a short, sharp shout in the mare’s direction. In some cases, sedation or tranquilization may be necessary. Dose and frequency largely depend on individual patients and clinician’s experience. In addition to standard phar8

Issue 1/2015 | ModernEquineVet.com

maceutical intervention, the staff at Claiborne Farm uses a concaveation technique that is slightly modified from the protocol described by Dr. Peter F. Daels. “First, we remove the foal from eyesight of the mare,” Dr. Scoggin explained. “Then we administer a relatively large dose of prostaglandin F2α. After about 15 minutes, the mare will become sweaty and uncomfortable, and we’ll apply a grafting spray to the foal and inside the mare’s nostrils to cover up any foreign odors.” After the foal is brought back to the stall, it is presented to the mare’s head, where she is allowed to sniff the foal and nuzzle it. The staff can then gently direct the foal back to the mare’s udder and allow it to nurse. “Almost miraculously, the mare will bond with that foal in a relatively short time.” This technique does come with some caveats. First, the mare can suffer adverse effects, such as colic, diarrhea and anxiety, associated with the large dose of prostaglandin

F2α. These effects are typically transient and self-limiting. “Also, we currently don’t know the exact mechanism of this protocol. It is likely due to the endogenous release of oxytocin, but we have not completely worked out the particular mechanism.” Dr. Scoggin also cautions that the methods described should be considered temporary, as they could lead to resentment from the mare or a negative association with the foal or nursing. Nurse mares, or surrogate mares, are an excellent option, but Dr. Scoggin notes they may not be available in certain situations. “I believe that using a nurse mare is a much better option than raising an orphaned foal. Orphaned foals can develop some pretty unsavory behavioral traits directed at humans and other horses. Use of a nurse mare will effectively eliminate the onset of orphan foal syndrome. It’s my clinical experience that foals raised on nurse mares do not suffer from developmental or health standpoint.” MeV

Photos by veterinary technician, Mary Stewart White, BS

Left: Dr. Scoggin tends to favor a lip chain over a nose twitch when more severe restraint is indicated. Right:: A padded barricade can safely restrict the mare's movements and enable the foal to nurse safely.

NOW AVAILABLE IN THE U.S. Over 250,000 doses administered worldwide in the last 12 years. Now FDA approved for use in the U.S. and available from your veterinary distributor, Tildren® (tiludronate disodium) controls clinical signs associated with navicular syndrome in horses. Tildren works at the areas of active bone resorption, restoring balance to the process of bone remodeling. Contact your local distributor or Ceva Animal Health representative for more information.

Do not use in horses with impaired renal function or with a history of renal disease. NSAIDs should not be used concurrently with TILDREN. Concurrent use of NSAIDs with TILDREN may increase the risk of renal toxicity and acute renal failure. Horses should be observed closely for 4 hours post-infusion for the development of clinical signs consistent with colic or other adverse reactions. Caution should be used when administering TILDREN to horses with conditions affecting mineral or electrolyte homeostasis (e.g. HYPP, hypocalcemia) and conditions which may be exacerbated by hypocalcemia (e.g. cardiac disease). The safe use of TILDREN has not been evaluated in horses less than 4 years of age, in pregnant or lactating mares, or in breeding horses.

TILDREN is a registered trademark of Ceva Santé Animale, France.

TILDREN.COM/US

ModernEquineVet.com | Issue 1/2015

Newsnotes

Bisphosphonate drug for intravenous infusion. For use in horses only. Brief Summary: See package insert for full prescribing information. Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian. Description TILDREN is a sterile powder. Each vial of TILDREN contains 500 mg of tiludronic acid (as tiludronate disodium) and 250 mg mannitol USP (excipient).

Indication TILDREN is indicated for the control of clinical signs associated with navicular syndrome in horses. Contraindications Do not use in horses with known hypersensitivity to tiludronate disodium or to mannitol. Do not use in horses with impaired renal function or with a history of renal disease. Bisphosphonates are excreted by the kidney; therefore, conditions causing renal impairment may increase plasma bisphosphonate concentrations resulting in an increased risk for adverse reactions. Warnings Do not use in horses intended for human consumption. NSAIDs should not be used concurrently with TILDREN. Concurrent use of NSAIDs with TILDREN may increase the risk of renal toxicity and acute renal failure. Appropriate wash-out periods should be observed between NSAID and TILDREN administration, and BUN and creatinine should be monitored. If treatment for discomfort is required after TILDREN administration, a non-NSAID treatment should be used. Human Warnings Not for human use. Keep this and all drugs out of the reach of children. Consult a physician in case of accidental human exposure. Precautions Approximately 30-45% of horses administered TILDREN will demonstrate transient signs consistent with abdominal pain (colic). Hand-walking the horse may improve or resolve the colic signs in many cases. If a horse requires medical therapy, non-NSAID treatments should be administered due to the risk for renal toxicity. Avoid NSAID use. TILDREN should be administered slowly and evenly over 90 minutes to minimize the risk of adverse reactions. Horses should be well hydrated prior to administration of TILDREN due to the potential nephrotoxic effects of TILDREN. Concurrent administration of other potentially nephrotoxic drugs should be approached with caution, and if administered, renal function should be monitored. Caution should be used when administering TILDREN to horses with conditions affecting mineral or electrolyte homeostasis (e.g. hyperkalemic periodic paralysis (HYPP), hypocalcemia, etc.) and conditions which may be exacerbated by hypocalcemia (e.g. cardiac disease). TILDREN should be used with caution in horses receiving concurrent administration of other drugs that may reduce serum calcium (such as tetracyclines) or whose toxicity may exacerbate a reduction in serum calcium (such as aminoglycosides). Horses with HYPP (heterozygous or homozygous) may be at an increased risk for adverse reactions, including colic signs, hyperkalemic episodes, and death. The safe use of TILDREN has not been evaluated in horses less than 4 years of age. The effect of bisphosphonates on the skeleton of growing horses has not been studied; however, bisphosphonates inhibit osteoclast activity which impacts bone turnover and may affect bone growth.

Lone Star tick may harbor unusual hemorrhagic virus University of Florida researchers have discovered that the Lone Star tick may harbor an unusual virus that belongs to the family Arenaviridae. Some arenaviruses are associated with severe hemorrhagic disease and significant mortality in people in South America and sub-Saharan Africa. Known as Tacaribe virus, the virus discovered in ticks has never before been found in an animal or human being in the United States, report scientists from the UF colleges of Veterinary Medicine and Public Health and Health Professions in a study that appeared in the journal PLOS ONE in December. The researchers found evidence of the virus in nearly 10% of ticks trapped and cultured in North Central Florida. Although Tacaribe virus is not known to cause human infections, the association that other viruses in the arenavirus family have with human illness, its relative rarity and unknown host in nature intrigued the study’s authors. “This finding is exciting because it expands the range in which these viruses might be circulating in the environment,” said Katherine Sayler, PhD, who completed her doctoral degree from the UF veterinary college in December and is the study’s lead author. “It also raises some really interesting questions about human risk.” Tacaribe virus was last isolated in bats during a rabies surveillance survey conducted in Trinidad in the late 1950s. Only one sample of Tacaribe virus from that survey remains, and molecular testing confirmed that the new tick-derived viral specimen was

Bisphosphonates should not be used in pregnant or lactating mares, or mares intended for breeding. The safe use of TILDREN has not been evaluated in pregnant or lactating mares, or in breeding horses.

nearly identical genetically to that remaining sample, according to the researchers. “We never thought we would find an arenavirus in a tick,” Sayler said. “These types of viruses are usually transmitted by rodents.” Although Tacaribe virus had been found in bats, recent studies indicate that bats are not the natural reservoir host, and efforts to find the virus in other mammals have failed. “We still don’t know which animal is the natural host of this virus, and whether ticks have harbored the virus for a long time, or if this is something new,” Sayler said. “Without knowing if local rodents are a major reservoir of the virus, the extent that Floridians are sickened by the virus, and whether ticks can transmit the virus to humans, it makes it hard for us to know if and when there would be an outbreak. Clearly, much more work must be done.” Lone Star ticks are common throughout the southeastern part of the country. MeV

Veterinarians Examine Benefits of Abdominal Bandages

Increased bone fragility has been observed in laboratory animals treated with bisphosphonates at high doses or for long periods of time. Bisphosphonates inhibit bone resorption and decrease bone turnover which may lead to an inability to repair microdamage within the bone. In humans, atypical femur fractures have been reported in patients on long term bisphosphonate therapy; however, a causal relationship has not been established.

While colic surgery in horses is a common procedure for large animal veterinarians, patient care after surgery is often debated. To help remedy this situation, a team of Kansas State University veterinarians examined the benefits bandages might provide following abdominal surgery.

Adverse Reactions: The most common adverse reactions reported in the field efficacy and safety studies were clinical signs consistent with abdominal discomfort or colic. Other reported signs were frequent urination, muscle fasciculations, polyuria with or without polydipsia, and inappetance/anorexia. For technical assistance or to report suspected adverse reactions, call 1-800-999-0297. Marketed by: Ceva Animal Health, LLC Lenexa, KS 66215 Tildren® is a registered trademark of Ceva Santé Animale, France NADA 141-420, approved by the FDA

Issue 1/2015 | ModernEquineVet.com

ophthalmology

How to repair

eyelid lacerations B y

K a t h l e e n

O g l e

Eyelid lacerations are com-

mon in horses and need to be treated as surgical emergencies to preserve the cornea. “Eyelid lacerations are usually caused by nails and hooks protruding from boards in the barn or stall, from fence wire or tree branches, or from sharp metal protuberances in trailers,” explained Diane V.H. Hendrix, DVM, a professor of ophthalmology at the University of Tennessee College of Veterinary Medicine. She outlined the steps she uses to evaluate and repair eyelid lacerations, which are common in horses and need to be treated as surgical emergencies. When repairing eyelid lacerations, Dr. Hendrix advised veterinarians to avoid excising the pedicle and to use a figure-eight suture configuration with a small needle and fine suture. Eyelid lacerations need to be repaired quickly, Dr. Hendrix said, or the skin pedicle will die. Most lacerations can be repaired in the standing heavily sedated horse, which is faster and safer for the horse, she said. She emphasized the importance of not excising pedicles involved with lacerations, keeping the eyelid margin intact and aligning the eyelid margins. “The eyelid’s purpose’s is to keep the tear film spread evenly, it’s also to get debris and plant material off of the cornea. So they really need to be able to close well and to close smoothly,” she said. Dr. Hendrix does the initial

This horse suffered a laceration of the upper eyelid with multiple tears in the skin. No skin was excised from this eyelid prior to repair. The pedicles of skin were incorporated into the sutures.

The same horse as in Figure 1 immediately post repair. Repair was successful in restoring eyelid integrity and function. The swelling was resolving by the following day. ModernEquineVet.com | Issue 1/2015

ophthalmology

ocular examination without sedation or nerve blocks. If there is periocular swelling, she looks at the symmetry of the orbits and sinuses, then palpates the orbital rim to determine if there are any fractures. She has seen horses, particularly foals that were hit hard or kicked in the face, with collapsed sinuses, If the menace response and the palpebral reflexes are normal, she

sedates the horse before doing a complete ocular examination. She starts with detomadine while doing the exam, and when she’s ready to suture she adds butorphanol for pain control. She blocks the auriculopalpebral nerve, which closes the eyelids, as well as the trigeminal nerve. Dr. Hendrix injects 1-2 mL of 2% lidocaine subcutaneously near the

This horse had a laceration in the lower eyelid.

branch of the auriculopalpebral nerve and does a line block peripheral to the laceration.

The ocular examination

Dr. Hendrix uses a direct ophthalmoscope and Finoff transilluminator. Because there may be a lot of blood over the cornea, she frequently postpones the retinal exam until the next day when the horse isn’t as painful. “You want to make sure that the cornea is intact and the blood isn’t coming from inside the eye. You want to make sure your pupillary light responses are present,” Dr. Hendrix said. If the affected eye has a smaller pupil than the opposite eye it means there is subclinical uveitis, which needs to be addressed with therapy. She recommended looking at the eyelid margins and conjunctiva very carefully as it is common to have two eyelid lacerations. “Usually there is a big one and then it seems that there is almost like a releasing laceration because of the trauma,” she said. Fluorescein staining to examine the cornea can help assure that the veterinarian does not overlook a laceration. It is also important to look at the anterior chamber; fibrin or edema could indicate severe trauma to the globe.

Preparation for surgery

This is the same horse as in Figure 3 with the eyelid repaired using the figure-eight suture pattern.

Issue 1/2015 | ModernEquineVet.com

Dr. Hendrix uses dilute betadine solution and saline, which allows her to prep thoroughly without worrying about it getting into the eye. She advised against using rubbing alcohol or betadine scrub, which are toxic to the epithelium. She anesthetizes the cornea even though the surgery is not being performed on the ocular surface. “Sometimes your suture is going to hit it or if the horse moves and your needle holder happens to touch the cornea they are going to jump,” she said. Using topical proparacaine

Unlike performing surgery in other parts of the body, in which the suture and knot are buried in deep tissue, knots should not be buried with an eyelid laceration. ophthalmic solution or lidocaine in a 1-cc syringe, she breaks off the needle and sprays it on the cornea. “Stay six inches from the eye because I’ve seen horses jerk when that fluid hits them. Even though you’ve broken off the needle it’s still very sharp,” she said. There will be severe swelling and congestion; however, with most eyelid lacerations, no tissue has actually been ripped away. “These eyelid pedicles can be so swollen they kind of almost start to shrink up in length. I’ve seen so many cases where it was felt that eyelid tissue had actually been removed, and the eyelid margins were not brought together in contact. Very, very rarely is the eyelid tissue removed or ripped away. You want to assume that you are going to do a simple apposition of eyelid margin to eyelid margin and then all that swelling will go away.” If the tissue looks devitalized, she uses either dry sterile 4x4 gauze to rub the tissue and scarify it or a scalpel blade to scrape it. “Really try to avoid taking scissors and actually excising that tissue because there is no redundancy and if you make things too tight you are going to end up getting dehiscence from your repair,” she warned. “Never simply excise the pedicle,” she continued. “Even if you think it is dead, try to replace it. The eyelids are so vascular that a lot of times even if the tissue is dying, it will recanalize, and you can actually get a blood supply back to the tissue. You would be much better to try and fail then to not try at all.”

Simple two-layer closure

Dr. Hendrix’s favorite suture is 5-0 polyglactin 910 with a spatula or cutting needle. “It has very good knot-handling ability. When it gets wet it’s very soft. It’s really nice not having to remove these sutures,” she said. She uses Bishop-Harmon forceps, Derf or Castroviejo needle holders, Stevens tenotomy scissors. The stroma is apposed with simple continuous or simple interrupted sutures. The knot of this suture must be oriented away from the conjunctiva and toward the skin. “No matter how you place the sutures, whether they are in the correct place or not, they are still going to be in very close proximity to the cornea. A couple tenths of a millimeter can make a difference in whether you are going to get a corneal ulceration from your suture placement,” she said. Unlike performing surgery in other parts of the body, in which the suture and knot are buried in deep tissue, knots should not be buried with an eyelid laceration. “I have seen so many cases when this has been done in the eyelid, and the knot is tied so it is buried against the cornea. That is the very last thing you want to do,” she said. “You do not want your suture to ever go to the conjunctival layer.” Next the eyelid margin is apposed with a figure-eight suture, which she described as going into the skin, coming out into the stroma, going in the stroma on the opposite side, coming out of the meibomian gland openings, going across to the opposite side, going in the meibomian gland openings coming out through the stroma,

Figure 5

Figure 6 Figure 5: Placement of the figure-eight suture pattern. The needle enters the skin just behind the eyelid margin (1, blue suture), exits the stroma of the eyelid, and enters the stroma on the opposite side. The suture is then made to exit on the eyelid margin at the line of meibomian gland openings and is passed externally (2, purple) to enter the meibomian gland opening on the opposite side. For the third pass, the suture is passed out of the eyelid stroma, across to the stroma on the opposite side and made to exit the skin behind the eyelid margin (3, magenta). Figure 6. The complete figure-eight suture is shown. The tags from the figure-eight suture (1) are laid across the knot from the first simple interrupted suture knot (2) to prevent them from contacting the cornea.

going back in the stroma on the opposite side and coming out the skin. “The sutures are mirror images of each other,” she said. “They are going to be shorter than what you think, maybe 2 mm tall.” Then she does a simple interrupted suture behind the figure eight in which she keeps the tags long. “Keep the tags incorporated in your second knot and that stops the figure-eight suture from rockMeV ing forward,” she said. ModernEquineVet.com | Issue 1/2015

orthopedics

Tiludronate may offer solution for

navicular syndrome B y

MRI images courtesy of Hallmarq Standing Equine MRI

A recently approved drug

that inhibits the excessive bone remodeling associated with navicular syndrome may enable horses to return to work. Jean-Marie Denoix, DVM, PhD, discussed the use of tiludronate (Tildren, Ceva Animal Health) for the treatment of navicular syndrome at the 60th annual meeting of the American Association of Equine Practitioners held in Salt Lake City, Utah. The presentation was sponsored by Ceva.

Degenerative change in both the compact and trabecular bone of the navicular

Issue 1/2015 | ModernEquineVet.com

K a t h l e e n

O g l e

Conventional management and treatment of navicular syndrome include trimming and shoeing, and intra-synovial injections with steroids. Palmar digital neurectomy may be the latest solution in horses with long-standing disease, according to Dr. Denoix, a professor of veterinary anatomy and equine lameness at the Ecole Nationale VĂŠtĂŠrinaire d'Alfort in Paris, France. Tiludronate disodium, which received FDA approval in May 2014 for the control of the clini-

cal signs associated with navicular syndrome in horses, is part of a class of drugs called bisphosphonates. In humans, bisphosphonates are used to prevent bone loss. They have been shown to reduce the risk of hip fractures in patients with osteoporosis. They have an analgesic effect and have been used to reduce pain and risk of fracture in patients with Pagetâ&#x20AC;&#x2122;s disease. Bisphosphonates are also used to treat pain associated with bone metastases, and

Hypointense signal with loss of trabecular pattern in the navicular bone

they may be useful in preventing the spread of metastases. Bone remodeling is the continuous process in which osteoblasts form bone and osteoclasts resorb it. In diseased bone tissue this balance is disrupted. Bisphosphonates inhibit bone resorption by encouraging osteoclasts to undergo cell death, leading to a decrease in the breakdown of bone. In horses, intense work or excessive mechanical stresses on a bone or joint. Bony areas can undergo excessive remodeling. This excessive remodeling of the bone tissue occurs in a large proportion of the locomotor conditions from which horses suffer, particularly in degenerative osteoarticular conditions. Bone lysis causes the pain that leads to lameness, according to Dr. Denoix Although the exact mechanism of bisphosphonates in horses with

navicular disease is unknown, Dr. Denoix said that â&#x20AC;&#x153;tiludronate reduces osteolysis with the direct consequence of reducing pain.â&#x20AC;? He presented results of U.S. and European multicenter clinical trials which compared tiludronate with placebo in the treatment of horses with navicular disease.

European multicenter trial

In the European multicenter trial, horses with moderate to severe navicular disease were divided into three groups: One placebo group (12 horses) and two groups treated with IV tiludronate sodium at a dose of 0.5 mg/kg (18 horses) and 1 mg/kg (20 horses). All horses received 10 daily injections. In the group treated at 0.5 mg/kg, the horses received five injections of tiludronate at the dose 0.1 mg/kg/ day and five placebo injections. In the group treated at the dose 1 mg/

kg, they received 10 injections at the dose of 0.1 mg/kg/day. Clinical examinations, which were videotaped, were performed at one month, two months and six months after the end of treatment. A second radiological examination was performed at the end of followup period. On horses presenting clinical manifestations for less than 6 months, the failure rate was dosedependent: 0% at the dose of 1 mg/ kg, 17% at the dose of 0.5 mg/kg and 56% in the placebo group, according to Dr. Denoix. Sixty seven percent of horses positively responded to treatment versus 12.5% in the placebo group, Dr. Denoix reported. The number of horses with a normal level of activity regularly increased over the follow-up period at the dose of 1 mg/kg (8% at inclusion, 60% two months post treatment

Flexor surface erosion in the navicular bone

ModernEquineVet.com | Issue 1/2015

orthopedics

and 75% six months post treatment) whereas it remained stable in the placebo group (around 25%). At six months, 50% of the horses treated at the dose of 1 mg/kg experienced a reduction in lameness compared with 27% of horses treated with 0.5 mg/kg and 12.5% in the placebo group. For chronic cases of navicular disease, the response to treatment was judged as positive in 63% of cases at the dose 1 mg/kg, Dr. Denoix said, but two or three treatments two months apart were sometimes needed for improvement.

U.S. multicenter trial

In the United States, 24 investigators at 12 equine clinics participated in a placebo-controlled blinded study to evaluate the effectiveness of tiludronate plus corrective shoeing compared with the effectiveness of corrective shoeing alone. Two hundred and eight horses diagnosed with navicular syndrome were enrolled in the study, and 204 horses completed the study with 136 treated with tiludronate plus corrective shoeing and 68 with corrective shoeing plus placebo. In this trial the medically treated horses received with 1 mg/kg tiludronate administered as a single IV infusion. The final evaluation took place at two months; success was considered an improvement of one lameness grade. Dr. Denoix reported a success rate of 64% in horses treated with tiludronate

versus 48.5% in horses treated with placebo. “Tiludronate administered with corrective shoeing was more impressive than shoeing alone,” Dr. Denoix said. “This underlines the need for medical management of the horse.” In treating horses who show signs of navicular disease with tiludronate, Dr. Denoix emphasized not waiting for radiographic changes. “The practical aspect is there is no need to wait for radiographic changes in navicular disease,” he said. “It is better to treat the horse before lysis is present.”

NSAIDs contraindicated

An FDA advisory warns that NSAIDs should not be used concurrently with tiludronate as it may increase the risk of renal toxicity and acute renal failure. A single dose of 1 mg tiludronate disodium per kilogram of body weight should be administered as an IV infusion slowly and evenly over 90 minutes to minimize the risk of adverse reactions. Adverse reactions in horses treated with tiludronate most commonly occurred during the infusion or within four hours after the infusion. The most common reaction (30% to 45%) was transient signs of colic. When giving tiludronate, veterinarians should advise owners of the potential for adverse reactions in the hours or days following treatment. Make sure that owners understand that they should consult you before giving their horse any NSAID after treatment with tiludronate. MeV

Shutterstock/ Edoma

For more information:

Denoix JM, Thibaud D, Riccio B. Tiludronate as a new therapeutic agent in the treatment of navicular disease: a double-blind placebocontrolled clinical trial. Equine Vet J. 2003; 35:4:407-13. FDA provides equine veterinarians with important information about Tildren and Osphos for navicular syndrome in horses: www.fda.gov/AnimalVeterinary/ResourcesforYou/ucm406581.htm

Issue 1/2015 | ModernEquineVet.com

AAEV T M E M b E r s h i p Membership in the AAEVT is open to all veterinary technicians, assistants, support staff and those employed in the veterinary health care industry worldwide. Student membership is open to those currently enrolled in an AVMA/CVMA accredited veterinary technology program.

AAEVT Membership • • • • • • • • • • •

Bi-Annual Newsletter Weekly “HoofBeats” Email Newsblast Full access to www.aaevt.org, including the Career Center and the Library Up-to-date information on the AAEVT Discounted registration for AAEVT Regional Meetings and the annual AAEP/AAEVT Convention NTRA, Working Advantage and Platinum Performance Benefits The opportunity to participate in the AAEVT Online Certification Program or to become a member of the AEVNT Academy-Specialty in Equine Veterinary Nursing Scholarship opportunities. AAEVT’s Equine Manual for Veterinary Technicians (Blackwell Publishing 20% discount on purchase price) Opportunity to attend Purina’s Annual Equine Veterinary Technician Conference - All Expenses paid!

AAEVT Objectives • • • •

Provide opportunities for CE, training, communication, and networking Educate the equine veterinary community and the public about our profession Inform Members of issues affecting our profession Assist in providing the best medical care to improve the health and welfare of the horse

AAEVT Online Equine Certification Program

• A three course, 10 module, equine-only online program offered through ACT • Geared toward Credentialed Veterinary Technicians, Assistants, Support staff, & Students • Areas of study include: equine medical terminology, anatomy and physiology, parasitology, laboratory, diagnostics, equine basics (breeds, wellness, husbandry,) diagnostic procedures, emergency medicine, restraint, pharmacology, surgical assistance and anesthesia, equine office procedures • A certificate of completion is awarded to those who: Successfully complete required courses Complete the list of required skills (per a supervising DVM who is an AAEP member) Attend an AAEVT regional CE symposium and participate in the we labs • Those individuals who successfully complete the programs will be recognized as AAEVT Certified Equine Veterinary Technicians / AAEVT Certified Equine Veterinary Assistants depending on their current designation. The certificate is recognized by the AAEVT and the AAEP but does not grant the credentialed status by the AVMA • For more information go to www.aaevt.4act.com or call 800-357-3182

AAEVT Mission Statement: To promote the health and welfare of the horse through the education and professional enrichment of the equine veterinary technician and assistant.

Fo r m ore in f or m at ion vist www.aae vt. org

*American Association of Equine Veterinary Technicians and Assistants

technician update

Rhodococcus equi: ubiquitous but deadly By Sharon Klingler, RVT, VTS(Anesthesia, EVN)

Noah D. Cohen, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University

The ubiquitous bacterial organism, Rhodococcus equi, causes several distressing conditions in foals, including pneumonia, septic arthritis, neonatal diarrhea, abdominal and spinal abscesses and sudden death.

A plate with modified NANAT medium and isolates of Rhodococcus equi growing. Note their salmoncolored, mucoid appearance.

Issue 1/2015 | ModernEquineVet.com

Because the organism is found in dry, dusty soil it is common in the environment when foaling is at a high. Foals seem to become infected by breathing in soil, dust and/or manure particles infested with the bacteria during the first week of life. The organism has simple nutritional requirements and can survive and thrive in equine manure, which enables it to multiply in large numbers on any horse farm, especially when the temperature is 86° F or higher. Dusty, manure contaminated areas like loafing sheds or foaling paddocks can be sources of infection. It is estimated that 1 tablespoon of dust can contain a million or more of the bacteria. The ideal time for foaling is in the cold wintery months of January and February when the R. equi is dormant in the frozen ground. R. equi has little problem becoming endemic on breeding farms and can cause monetary losses due to the high costs of diagnosis and treatment of affected foals. It can also cause the death of foals. There appears to be a correlation between the number of organisms in the environment and the number of foals that develop pneumonia, which could be as high as 60% of foals on a given farm. Since the foal spends a lot of time on the ground, it is easy to see how they can be infected when they inhale the dust and dirt that is kicked up when the mare moves around the stall. Once inhaled, R. equi infection is enhanced by rapid multiplication in the foal’s intestine. Because it takes one to 12 weeks for the foals to establish normal intestinal flora, they seem to be especially susceptible to infection. It has been documented that as many as 10,000 bacteria are shed by foals in each gram of manure they produce. The organism appear to only reproduce in very young foals. Once the foals reach 12 weeks of age, it appears that the bacteria no longer can reproduce and their numbers decline rapidly. The number of cases of R. equi seems to reach a peak when foals are 6-12 weeks old. This is the period when the level of maternal antibodies the foals receive from colostrum is low and the foals’ natural antibodies are also low (or at least not fully developed). This makes the amount of colostrum the foals receive upon birth even more important. The foals stop being susceptible to the R. equi by 5-6 months of age probably because they produce antibodies to the organism. Most never show signs of disease. Because full immunity to R. equi does not seem to be complete until 5-6 months, natural im-

news notes

munity is inadequate when the foals are at the greatest risk during months 1-4 when they are inhaling large amounts of dust and manure particles.

Environmental steps

Unfortunately, there is no vaccine to give to pregnant mares or newborn foals to protect against this organism. Therefore, the best way to protect the foals from this aggressive organism is to try to limit the numbers in the environment. Due to the types of footing used in breeding farms, disinfection is hard to do in stalls and almost impossible in pastures and loafing sheds. The best way to use disinfectants would be to have concrete floors in the stalls which is impractical or to use mats over the dirt which can limit but not totally eliminate contact. Diligent cleaning up of manure from the areas where foals are housed can be effective in reducing the numbers of R. equi. Keeping loafing paddocks from getting over grazed and turned into “dust bowls” and making sure there is grass at all times is another valuable practice. One way to keep from infecting your farm with R. equi is to make sure you do not send a young foal with its mother to another farm while she is being bred if that farm has a history of R. equi infections. Foals with R. equi can become quite sick before they show many symptoms. The foals remain active, bright and alert and nurse well even after they start to run a fever. At first the foals may wheeze and cough occasionally followed by an increased respiration rate. When the disease progresses, the foals can have crackling sounds during breathing that can be heard without a stethoscope. A nasal discharge is also present. The lungs of an infected foal can have multiple areas of abscesses. Affected foals need to be treated for 7-10 days past resolution of the disease. Treatment should be stopped only after clean radiographs and/or normal fibrinogen levels are achieved. The drugs of choice are a combination of erythromycin and rifampin which can be given orally in a paste or suspension. They are not toxic over prolonged treatment periods. As we learn more about this disease and change our husbandry, we can better get it under control and keep our young foals healthy. MeV

About the author

Sharon Klingler RVT VTS(Anesthesia, EVN) is a veterinary technician at Premier Equine Veterinary Services in Whitesboro, Texas.

O-scan MRI installed in US veterinary center The self-shielding O-scan Equine MRI unit by Esoate was installed recently at the Tennessee Equine Hospital in Nashville, Tenn. The O-scan is particularly good for identifying articular cartilage pathology, bone edema, and soft tissue injury, which some low field magnets cannot distinguish, according to Monty McIntruff, DVM, the managing owner of Tennessee Equine. “Once the radiographer’s report is back in 24 hours, we can provide precise treatment, without any ‘wasted time.’ In practical terms, the O-scan is great in that it doesn’t require a lot of space or three-phase power (just 1:10 power, which is easier to come by). All in all, it’s been greatly accepted by our customers. When their horse is injured we can rapidly diagnose and treat to eliminate wasted time off from competition,” Dr. McIntruff said.

The O-scan is particularly useful for soft tissue diagnosis, including imaging within the hoof capsule such as the deep flexor tendon, the impar ligament and collateral ligaments of the coffin joint. “The images are excellent for diagnosis where ultrasound or radiography won’t help as much,” explained Henrik Sten Andersen, co-owner of Hørsholm Hestepraksis, one of Denmark’s largest veterinary clinics, which has had an O-scan for two years. They frequently share the scans with owners so they see the pathology for themselves. “They’re confident for us to treat or to leave the horse to recover, rather than calling us back a few weeks later, looking for an alternative diagnosis,” he said. The O-scan can clearly distinguish between lesions in bone, ligaments or tendons of the foot, pastern, fetlock and carpus thanks to the O-scan’s contrast resolution and image quality. Its new eXP software and hardware platform enables performance that is comparable to that of 1.5 Tesla systems. The O-scan is fast and simple to use thanks to its ‘position, plug in and play’ capabilities, helping provide a high degree of efficiency and a strong return on investment. Esaote offers other veterinary MRI solutions, including the G-scan Vet, designed for equine and small animal imaging, which has a 90° tilting magnet for equine stifle imaging, whereby the bore is oriented vertically. All horses are scanned under general anaesthesia in dorsal or lateral recumbency, with the hind limb of interest extended so that the femorotibial joint is centered to the magnet isocenter. Alternatively, with the system at 0°, high-quality imaging of small animals is enabled. The Vet-MR Grande represents Esaote’s most important development in MRI technology for veterinary diagnostic imaging. The Vet-MRGrande is suitable for mixed practices and clinics. Thanks to its flexible configuration, it can perform excellent examination of small animals, and of the equine limbs as well as the head. MeV ModernEquineVet.com | Issue 1/2015

The Modern

Equine Vet

Reach your veterinarians wherever they are, whenever they want. FOR ADVERTISING RATES AND INFORMATION, EMAIL Robin Gellar