Hind limb lameness in dogs: A Veterinary Surgeons Perspective

HIND LIMB LAMENESS IN DOGS: A VETERINARY SURGEON’S PERSPECTIVE

Paul Freeman MA VetMB CertSAO MRCVS The Veterinary Practice Millennium Way Braintree Essex CM7 3GX

Introduction

The following article includes an account of how I perform an investigation into hind limb lameness in dogs; it is not intended to be a definitive guide, but should provide an insight into the examinations and methods which can be utilised to arrive at a diagnosis.

Any discussion of the causes and treatments of hind limb lameness is greatly assisted by an understanding of the range of problems seen in different ages and breeds of dog. The old adage that “common things are common” should always be kept in mind, and the article provides a list of the more common conditions, although this is not intended to be exhaustive. Finally I have provided a brief overview of my current thoughts on one of the more common causes of hind limb lameness, cranial cruciate ligament disease.

The Lameness Investigation

In making a diagnosis of the cause of lameness, I always like to begin with a careful history taking. This need not take very long, but requires the ability to listen and extract the useful information from the dog’s owner. Owners often become side-tracked when discussing their dog’s problem, and sometimes will have decided what is wrong (or what cannot possibly be wrong), before seeking assistance. Apart from ascertaining the age and breeding history, the important things are whether the lameness is acute or chronic, whether there was a known incident that precipitated the problem, whether it is progressive or static, and whether it is improved or exacerbated by rest and/or exercise.

The next step is to assess the dog moving; it is very common to be presented with a dog for lameness examination of the wrong leg! I always like to see the dog moving outside of the surgery at trot and walk; even when the problem appears severe and obvious, other things may be observed such as the existence of bilateral disease or a neurological problem. Once it is clear which leg(s) is/are affected, a thorough physical examination should be performed.

A systematic approach should always be taken in order to minimize the risk of missing an important feature. I prefer to start with the foot and move proximally, except where I am very suspicious the problem is located in the foot, in which case I will begin proximally and leave the painful region till last. During the physical examination, it is important not to over interpret signs of pain or discomfort. Some dogs can be very fidgety, especially when handling their feet, and I always try to compare response to a similar examination of the contralateral limb. Once the painful region has been established, I also like to check that the response is repeatable.

The physical examination is vital, since multiple pathologies may be revealed by radiographs; it is particularly important to establish the location of the problem when surgical treatment may be proposed. As well as a pain reaction, palpation may reveal joint swelling, muscle wastage or the presence of an abnormal mass, all of which may be significant.

Once the location of the lameness has been established, further investigations may be proposed, including initially radiography and perhaps arthrocentesis. Radiography is still the main-stay of orthopaedic investigation, and good quality radiographs centred on the affected area are vital. Poor radiographs may suggest non-existent pathology or miss the presence of subtle changes, and are a frequent cause of non diagnosis. Arthrocentesis is a relatively simple and minimally invasive technique which can normally be performed under sedation, and forms part of any examination into joint pathology (1). Samples of joint fluid can be taken from almost any joint, particularly if the joint is inflamed; cytology of this fluid can be performed quickly in a practice laboratory, and can be a sensitive way of confirming the location of intra-articular pathology, as well as diagnosing inflammatory and septic arthritis.

It is rare that further investigative techniques are required, but on occasions further imaging may be helpful. Computed Tomography (CT) scanning is especially useful in the diagnosis of elbow dysplasia in the fore limb; Magnetic Resonance Imaging (MRI) scanning is occasionally useful in diagnosing soft tissue tumours; and scintigraphy is a sensitive method for picking up subtle and difficult to detect lesions. More invasive techniques such as arthroscopy or even open arthrotomy are also sometimes necessary to reach a final diagnosis, particularly in cases of meniscal injury secondary to cruciate ligament disease. In cases of neurogical lameness such as lumbosacral disease and nerve tumours, MRI is probably the most accurate diagnostic method, but Electromyographic (EMG) changes may also be found which are highly suggestive of the source of the problem.

Differential Diagnoses

Once the source of lameness has been established, a knowledge of the differential diagnoses becomes very helpful, and will aid the application of the appropriate investigative

technique. The following list is by no means exhaustive, and there is much crossover between my differing categories, but it is meant to provide a simple guide to which are the most likely and unlikely causes of lameness in different ages and breeds of dog.

1. Hip/Proximal Limb Pain

a. Immature Dogs Hip Dysplasia (HD) – Radiography – susceptible (larger) breeds. Panosteitis – Radiography – German Shepherd Dog (GSD) especially prone. Legg Perthes Disease (LPD) - Radiography – Small breeds especially West Highland White Terriers. Proximal femoral physeal fracture – Radiography.

b. Adult dogs Hip Osteoarthritis (OA) – secondary to HD or LPD. Radiographs and arthrocentesis. Trauma e.g. fracture/luxation - History. Lumbosacral disease – larger breeds especially GSD. Neoplasia – bone or soft tissue.

2. Stifle Pain

a. Immature dogs Distal femoral physeal fracture – History + Radiographs. Tibial tuberosity avulsion (especially Staffs) – Radiographs, compare contralateral side to be sure. Avulsion of the cranial cruciate ligament (CCL) - Radiographs. Septic stifle arthritis - Arthrocentesis. Panosteitis - Radiographs. Patella luxation – medial (small and toy breeds) or lateral (large breeds especially Flat Coated Retriever). – Physical examination and radiography. Inflammatory Polyarthritis - Arthrocentesis.

b. Adult Dogs CCL disease – see later – all breeds except Greyhound. Inflammatory Polyarthritis Trauma. Sepsis. Patella luxation. Stifle OA – suspect CCL disease (rarely primary). Neoplasia – distal femur and proximal tibia are common sites for osteosarcoma.

3. Lower Limb

a. Immature Dogs Hock Osteochondritis Dissecans (OCD) – Radiographs – Labrador. Avulsion fractures – calcaneus and malleoli - Radiographs. Toe injuries (trodden on!). Trauma. Inflammatory Polyarthritis.

b. Adult Dogs Inflammatory Polyarthritis. Plantar ligament breakdown/injury – Stressed Radiographs – Sheltie. Hock OA – secondary to injury or OCD. Inter digital Foreign body – Spaniels and other working dogs. Achilles injury / breakdown – Doberman Pinscher. Corn – Greyhound. Trauma. Neoplasia.

Cruciate Disease

The cranial cruciate ligament (CCL) functions to prevent cranial movement and inward rotation of the tibia during weight bearing. It is also believed to have a role in conscious proprioception of the hind limb.

Disease or injury to the CCL in dogs accounts for a very high proportion of hind limb lameness seen in veterinary practice, although unlike the human equivalent, the majority of canine CCL disease is not traumatic in origin. Occasionally we are presented with a dog that has obviously ruptured a CCL acutely in a traumatic incident such as running over a ploughed field; more often though the onset is insidious and chronic, with marked secondary OA already present at the time of diagnosis. Even many apparently acute ruptures can be shown to be acute episodes of a chronic disease, with careful history taking and radiographs demonstrating the true nature of the problem.

Dogs with CCL disease may have lameness varying from severe to slight. Characteristically they rest the affected limb when standing, and struggle to flex the stifle when sitting. The stifle joint is usually thickened and painful, especially during forced extension and medial palpation, and sometimes a cranial drawer movement or tibial thrust may be palpated with the dog conscious. In these cases the diagnosis is easy to make, and the ligament is likely to be completely ruptured. Often a marked lameness can be caused by only partial CCL tearing however, and in such cases the diagnosis may be less obvious. Radiographs are likely to demonstrate a joint effusion and early OA; joint fluid should contain increased numbers of synoviocytes; a degree of cranial drawer can usually be palpated under sedation or general anaesthesia. In a small number of cases where the index of suspicion is high but no instability can be demonstrated, final diagnosis may only be confirmed at arthrotomy.

Care must also be taken in cases of bilateral CCL disease; these can present with the dog acutely unable to walk, and may be misdiagnosed as a spinal problem. Again a careful physical examination should reveal bilateral stifle pain and instability.

Once a diagnosis of CCL disease is made, treatment options must be discussed. Conservative treatment should always be considered in small dogs of 10kg and under (2). This consists of a period of exercise restriction, usually accompanied by the use of non steroidal antiinflammatory drugs (NSAID’s). Physical therapy techniques aimed at increasing quadriceps muscle bulk may also be helpful.

Where this is unsuccessful, and in larger dogs, surgical treatment should be considered. Currently most orthopaedic surgeons favour either an extra capsular stabilisation technique involving replacing the function of the CCL with a laterally placed nylon suture, or a tibial osteotomy procedure.

This can be very successful in all sizes of dog, but is generally now recommended for lighter and older dogs. An arthrotomy or arthroscopy should always be performed concurrently to check for meniscal injury, since this may be a cause of persistent lameness following surgery (4). The stifle joint is stabilized by placing a nylon suture between the lateral fabella and the tibial tuberosity. Post-operatively, a gradually increasing regime of short, frequent lead walks over about 6-8 weeks is normally recommended. Hydrotherapy twice weekly from 2 weeks post-op for 2-4 weeks also appears to be very beneficial.

Tibial Osteotomy Surgery

A variety of techniques aimed at changing the angle of the proximal tibial plateau have now been shown to be effective in treating CCL disease (5). These procedures appear to be advantageous in particularly young large breed dogs, and in cases of bilateral disease. It is believed that an excessive caudal slope on the tibial plateau predisposes the CCL to fail, and that changing this in a pre-measured way can effectively eliminate the need for CCL stabilisation of the joint. The currently used techniques include:

The Tibial Plateau Levelling Operation (TPLO) (6)

The Cranial Closing Wedge (7)

The Tibial Tuberosity Advancement (TTA) of Tepic (8)

The Triple Tibial Osteotomy (TTO) of Bruce (9)

A detailed account of the surgery involved is beyond the remit of this article, but any reader interested is recommended to see the Veterinary Instrumentation web site at www. veterinary-instumentation.co.uk for further information and videos of these procedures. As with the lateral suture technique, an arthrotomy is first performed in order to check for meniscal injury.

Post-operatively dogs are required to be rested strictly for the first month, before beginning a gradually increasing programme of lead walking and physical therapy. Hydrotherapy should be delayed until after a 6 week radiograph confirming osteotomy healing. Physiotherapy involving passive range of motion exercises may be employed from an early stage. However, despite the popularity of these techniques, there is a shortage of evidence to support the belief that they provide an improved longterm function over other surgical techniques particularly lateral suture (10), and individual surgeons tend to develop protocols for management of CCL disease based on personal experience and largely anecdotal evidence.

As stated at the beginning, this article is not intended to provide a complete guide to hindlimb lameness in dogs, but is intended to give a personal perspective on how an investigation of lameness can be performed, an outline of commonly seen conditions, and a brief overview of treatment options for CCL disease. The references provided below will allow the reader to further explore this complex subject.

References

1. BSAVA Manual of Small Animal Arthrology, Ed JEF Houlton and RF Collinson, 1994.

2. Vasseur PD: “Clinical results following nonoperative management for rupture of the cranial cruciate ligament in dogs”. Vet Surg 13, 243-246, 1984.

3. Flo GL: “Modification of the lateral retinacular imbrication technique for stabilizing cruciate ligament injuries.” J Am Anim Hosp Assoc 11, 570-576, 1975.

4. Flo GL: “Meniscal Injuries.” Vet Clin North Am Small Animal Practice 23: 831-843, 1993.

5. Kim SE, Pozzi A, Kowaleski MP, Lewis DD: “Tibial Osteotomies for cranial cruciate ligament insufficiency in dogs.” Vet Surg 37, 111-125, 2008.

6. Slocum B, Slocum TD: “Tibial Plateau Levelling Osteotomy for repair of cranial cruciate ligament rupture in the canine.” Vet Clin North Am Small Anim Pract 23: 777-795, 1993.

7. Slocum B, Devine T: “Cranial tibial wedge osteotomy: a technique for eliminating cranial tibial thrust in cranial cruciate ligament repair.” J Am Vet Med Assoc 184: 564-569, 1984.

8. Montavon PM, Damur DM, Tepic S: “Advancement of the tibial tuberosity for the treatment of cranial cruciate deficient canine stifle.” Proceedings of the 1st World Orthopedic Veterinary Congress, Munich, Germany, P.152, 2002 (abstract).

9. Bruce WJ, Rose A, Tuke J, Robins GM: “Evaluation of the Triple Tibial Osteotomy. A new technique for the management of canine cruciate deficient stifles.” VCOT 20, 159-168, 2007.

10. Conzemius MG, Evans RB, Besancon MF: “Effect of surgical technique on limb function after surgery for rupture of the cranial cruciate ligament in dogs.” J Am Vet Med Assoc 226, 232-236, 2005.