ABSTRACT: Canine hip dysplasia (CHD) is a failure of the acetabulum and the femoral head, to develop into a well-seated, synonymous joint. The affected coxo-femoral joint will degenerate over time owing to its instability and will lead to progressive osteoarthritis. Diagnosis of CHD is confirmed by physical examination and radiographic evidence. CHD may be managed conservatively or surgically.

In all cases physiotherapy, including hydrotherapy, is essential to the success of the case.

Classification

CHD is a common condition, particularly in large dogs, and consists of two ‘classes’.

Class one includes dogs that are under one year of age. In these puppies, CHD starts with acute episodes of either bilateral or unilateral lameness of the hind limbs. Excessive exercise or minor trauma may make the lameness worse.

The symptoms of this type of juvenile CHD are: difficulty in walking, running, stair- climbing, jumping and soreness of the limbs. The puppy may be unwilling to play or exercise and a ‘bunny hopping’ gait may be seen, caused by pain on full extension of the hips. A visible or audible click may be noted on dislocation of the hip.

The second class of CHD includes dogs that are over 12 months of age. CHD in these dogs produces lameness with shifting from one side to the other and weight displacement to the forelimbs to help reduce the stress on the coxo- femoral joint. These dogs generally have well-built forelimb muscles as a compensatory effect.

Normally dogs will carry 60 per cent of their weight on the forelimbs, but in cases of CHD then this may increase to 90 per cent. This means that there is often notable muscle atrophy in the hind limbs. Often these dogs will have a ‘waddling’ gait and will choose to sit rather than to stand.

Diagnosis of CHD

Diagnosis of CHD is confirmed using physical examination and radiographic evidence. Radiographs are taken with the dog on its back with its pelvis lying symmetrically and both hind limbs extended and parallel to each other (sedation or anaesthetic is required to do this). The radiographs are assessed in a standard way taking breed variations into account.

Factors assessed are: the degree of subluxation of the femoral heads; the condition of the dorsal, cranial, and caudal acetabular rims; the shape of the femoral head and necks; new bone formation and evidence of osteoarthritis.

Control of future incidents of CHD depends upon strict selective breeding. Breeding stock should be radiographed at 12 months of age and the radiographs should be submitted to the British Veterinary Association/Kennel Club Hip Dysplasia Scheme, http://www.bva.co. uk/public/documents/ Hip_Dysplasia.pdf

Each radiograph is scored according to the above factors and low scores are suitable for breeding.

Figure 1 shows a radiograph of a bilateral luxation of the coxo-femoral joint. Figures 2 & 3 show more advanced diagnostic imaging in the form of magnetic resonance imaging (MRI) which is useful for more complex cases that may be difficult to diagnose with standard radiography.

Figure 1: Bilateral luxation of the coxo-femoral joint

Figures 2&3: This MRI scan shows the left femoral head distracted to a greater extent than the right indicating greater laxity associated with the left coxo-femoral joint. It is unusual to see hip dysplasia associated with clinical signs in a dog this small, without peri-articular osteophytosis

Conservative approach

Management of CHD depends on the dog’s age, amount of pain, body weight, severity of arthritis and activity levels.

Treatment of chronic osteoarthritis of the coxo-femoral joint includes: pain management, diet management, exercise moderation, physiotherapy and hydrotherapy.

Young dogs with unstable hips can do well with controlled exercise and strict maintenance of the correct body weight, and conservative management may allow the hip joints to stabilise by 15 to 18 months of age. Sometimes pain management is required.

Conservative treatment is most suitable for older dogs that are not physically or medically fit for surgery. Even with dogs that have severe osteoarthritis, some may cope well with conservative treatment and this is the realistic option for owners who do not have the finances for an operation or that will be unable to manage the post operative requirements.

fit Canine hip dysplasia (CHO) is a failure of the acetabulum and the femoral head to develop into a well-seated, synonymous joint. The affected coxo-femoral joint will degenerate over time owing to its instability and will lead to progressive osteoarthritis.

These owners need to be made aware that the osteoarthritis and hip changes will continue to degenerate even with conservative management. Conservative management includes exercise restriction, weight reduction, pain management and physiotherapy, including hydrotherapy.

Surgical options

Surgical treatments vary according to the animal’s age, weight and severity of arthritis. The most common surgical approaches to CHD include: triple pelvic osteotomy (TPO), femoral head and neck excision (FHNE), juvenile pubic symphysiodesis (JPS) or total hip replacement (THR).

Triple pelvic osteotomy

Immature dogs (six to 12 months old), dogs showing clinical signs of CHD and laxity of joint – but no evidence of osteoarthritis shown on radiographs – may find a triple pelvic osteotomy (TPO) most beneficial. The procedure involves three cuts into the pelvis – the third cut facilitating rotation of the acetabulum to allow more coverage and support of the femoral head. A bone plate and screws are used to secure the new positioning of bone.

In cases in which appropriate patients have been selected, this operation has been shown to reduce CHD and progression of osteoarthritis. Following surgery, strict rest, analgesia, cryotherapy, gentle massage, passive range of movement of the stifle and hock and assisted walking are required.

Femoral head and neck excision

A femoral head and neck excision (FHNE) is a surgical intervention whereby the femoral head and neck are removed in severe cases of osteoarthritis, owing to femoral head and acetabular fractures, or as a result of financial constraints. Smaller dogs that are not overweight (under 25kg) tend to recover more quickly generally and tend to have a better use of the limb than less active or overweight dogs.

When the femoral head and neck are removed, the supporting hip muscles and fibrous tissue provide support for the coxo-femoral joint. Physiotherapy is essential in reducing excess fibrosis and reduced mobility of the false joint. Postoperative physiotherapy includes passive range of movement, analgesia and controlled activities to enable active limb use.

Juvenile pubic symphysiodesis

Juvenile pubic symphysiodesis is a prophylactic procedure in which electrocautery is applied to the pubic symphysis, leading to asymmetric closure of the pelvic symphysis and the reduction of joint laxity. This procedure is only effective in dogs t
hat are under five months of age.

Total hip replacement

Total hip replacement (THR) involves highly specialised surgery, performed by specialist surgeons. It is indicated as a ‘salvage’ procedure to provide a pain- free and biomechanically useable hip in patients suffering with the osteoarthritis that is commonly caused by CHD.

In THR surgery, the femoral head and neck are removed and replaced with a polypropylene acetabulum and a stainless steel femoral neck and head. These implants may be secured to the bone using bone cement, or a coating into which the bone can grow, to maintain its position.

Following a THR, pain management, cryotherapy, passive range of movement and controlled exercise are recommended. The patient should be supported with a sling during its first stages of walking postoperatively and also care should be taken that abduction of the hind limb is avoided in order to prevent dislocation of the prosthesis, especially during the recovery period.

Most patients will start to bear weight straightaway and it is necessary to keep the patient on lead walks only. No running, jumping or playing should take place for 10 to 12 weeks postoperatively. This is to try and stop the chances of the prosthesis loosening or dislocating.

Because there is usually already muscle atrophy in most cases, it is a priority to include muscle strengthening into the postoperative physiotherapy regimen. Controlled walking, balance and proprioception training are all very important. 

Author

Sian Norris BSc(Hons) RVN Dip Animal Physiotherapy

Sian graduated from the University of Reading in 2001 with a Degree in Animal Science. During her spare time at university, she worked as a veterinary nurse and after graduating went on to gain her qualification as a Registered Veterinary Nurse in 2004. Sian has most recently completed a Diploma in Animal Physiotherapy and currently works as a ward rehabilitation co-ordinator at Fitzpatrick Referrals in Godalming.

To cite this article use either

DOI: 10.1111/j.2045-0648.2010.00017.x or Veterinary Nursing Journal Vol 26 pp 46-48

Bibliography

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 • VOL 26 • February 2011 • Veterinary Nursing Journal