Canine Hip Dysplasia in South Africa

Canine Hip Dysplasia in South Africa

-Dr. Mark Rubinsohn

Canine Hip Dysplasia (CHD) is a developmental disease seen most commonly in larger, well fed faster growing dogs. It causes a painful hip joint with persistent and unrelenting lameness. It is usually present in both hips, but the degree of severity may differ in the two hips. Although adverse environmental factors can influence hip joint development, CHD is essentially a disease with a high degree of heritability. It is a condition that may require medical treatment and often radical medical treatment. Eventually it may require Euthanasia of the dog.

Clinical Signs

From as early as 4 or 5 months the pup may show signs in difficulty of getting up, stiffness on rising, alteration in the manner of running, "bunny hops", pain after exercise and resentment to patting of hind quarters.
The arc of movement of the hind leg becomes greatly decreased, and as degenerative joint disease develops the thigh muscles atrophy.
The degree of lameness becomes worse after a couple of years and is aggravated by cold and damp weather.
It is possible for CHD to be present in dogs who show no visible lameness or gait abnormality.

Causes

It is a complex inherited disease weather the degree of severity of Dysplasia in the parents directly influences the frequency and severity in the pups. Even mild dysplasia in one parent will affect the risk of dysplasia developing in the progeny.
A high energy diet leading to rapid growing or overweight pups has a greater chance of producing dysplasia, especially if the growth spurt occurs at a sensitive time in skeletal and muscular development.
poor pelvic muscle mass and abnormal pelvis angulation will affect the hip joint.
Excessive activity in the young animal, especially if overweight or in the presence of exaggerated joint laxity can aggravate dysplasia.
Calcium intake may be an important factor with both excessive or insufficient calcium being detrimental to joint development.

Diagnosis

By radiographic evaluation of the hips it may be diagnosed as early as a few months of age. In South Africa certification may be done from one year of age. Correct positioning of the dog is important and is facilitated by sedation and anaesthesia.
Palpitation of joint laxity in the young pup is often one of the first diagnostic signs of CHD. This is also facilitated by anaesthesia.

Grading of Hip Dysplasia

South Africa: No signs of hip dysplasia
Transitional / Borderline - very minor incongruity

Grade I - mild shallowing of acetablum and flattening

of femoral head

Grade II - moderate changes

Grade III - Severe changes

Grade IV - Very severe with sublaxtion

Europe: Nine different areas of the hips are evaluated, each obtaining a score of 0 = normal to 6 - Very bad. Thus the best hips score 0/0 and the worst 54/54

Treatment

No therapeutic or surgical treatment will restore totally normal function. However, some measure of relief can usually be given to the dog crippled with CHD
Treatment is aimed at alleviating the pain caused by the degenerating joint disease by avoiding cold, damp areas; judicious exercise to maintain muscle tone with care not to overexert the joints; allowing adequate periods of rest; reducing weight in the obese dog; using analgesic and anti-inflammatory drugs; and resorting to surgical procedures where these methods are no longer effective.
Surgical procedures include the following:

*   Resectioning of pectineal muscle or tendon - the most common method used in less severe cases - affords significant functional improvement and reduction of pain within 24 to 72 hours but will not stop the further development of arthritic changes and thus lameness may return later in the dog's life, especially in colder weather.
*   Resectioning of femoral head -for severe dysplastic arthritic changes. This is occasionally done on both sides and is generally more successful on the lighter type dogs
*   Reangulation osteotomy of the pelvis or femoral head. This surgery is the best best for cases performed between four to eight months and is not worse than grade II or III.
*   Hip prosthesis which is expensive and to date results have not been impressive.

Control

As CHD is genetically influenced, radiographs can be used as an indication of a dog's desirablitity for breeding.
The breeding of two radiographically HD free dogs will not necessarily guarantee that their offspring will be HD free. An HD control programme in sweden showed that:

*        normal: normal matings led to 18 percent dysplastic offspring;
*        normal: dysplastic matings led to 59 percent dysplastic offspring.
*       dysplastic: dysplastic matings led to 87 percent dysplatic offspring.

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