v Understanding canine Hip Dysplasia

It’s very disheartening to see our loving pal suffer from canine hip dysplasia, which causes discomfort and mobility problems. Here are a few ways to improve or eliminate its symptoms.

Canine hip dysplasia (CHD) is the most common development disorder of the hip joint, characterized by abnormal development of the hip joint. It usually occurs in both hind limbs, affecting both hip joints. Its effect ranges from very mild lameness to a crippling disease. Lameness may appear at any age.

Hip dysplasia is a hereditary condition and breeding of affected animals should be discouraged. The best way is to breed dogs with disease free joints based on radiographic evaluation and who have come from families with disease free joints. Do not breed dogs whose offspring have hip dysplasia. Dogs with hip dysplasia can produce normal pups and normal looking dogs can produce hip dysplastic pups.

How it occurs?

The hip joint is a ball and socket joint. The ball (the top portion of the thigh bone or femur) fits into a socket formed by the bones of the hip called the pelvis. In hip dysplasia, there is a loose and improper fit between the socket and the femur, the ligaments which hold them together also become loose, hence causing the ball to slide out of the socket partially in the initial stages (subluxation) and completely in long standing cases. When this occurs repeatedly, the ball gets worn out unevenly, causing erosions on its surface and exposing the underlying bone. Subsequently, bony proliferations occur (osteophytes) eventually resulting in degeneration of the hip joint (Osteoarthritis) and the dog becomes painful, lame and weak in the affected limb.

It is caused by multifactorial-genetics (polygenic-caused by many different genes), environment and nutrition (increased calcium and/or high calorie intake). However, the development of the disease is influenced by body weight, size and rapid growth patterns.

What are the clinical signs?

There are two types of clinical signs :

• Young dogs who are between 5-8 months exhibit sudden decrease in activity, sore hindquarters, difficulty in rising and reluctant to walk or climb stairs. Initially, it may be noticed once in a while but will begin to get worse over time.
  
  
• Older dogs show intermittent or continuous hind limb lameness after exertion, prefer to sit than stand, stiffness or difficulty in rising, reluctance to run and jump, short choppy steps of the hind limbs, loose or waddling gait, bunny-hopping when running and painful hip joint with decreased range of motion of hip. Shoulder muscles are stronger and thigh muscles are weak. Lameness and pain is usually due to secondary degenerative joint disease (DJD) and osteoarthritis.

How can it be diagnosed?

• Physical examination : Laxity (excessive looseness of the hip), pain and/or crepitus (caused by rubbing of bony ends) of the hip joints.
  
  
• Radiography : X-rays are taken to see the fit of the femur and pelvis and to look for bony changes in the hip joint. This is done under sedation. The severity of clinical signs often does not correlate with the severity of radiographic signs. Special radiographic procedures are also available to hip joints. Radiographic changes are seen between 6-18 months after which the disease progression is slow. They are graded by the principles laid down by the Orthopaedic Foundation for Animals (OFA) as borderline, mild, moderate and severe based on the radiographic evidence of damage to the hip joints. Another method of evaluation is a Penn Hip distraction method. Please consult your vet for further details of these procedures.

Radiographs are done to screen for presence or absence of hip dysplasia to select dogs who are suitable for breeding.

How can it be treated?

There is no cure but your dog’s pain and lameness can be managed by following certain conservative management procedures :

• Restricting activity by limiting exercise to several regular 10 minute walks a day on a leash only for 6 weeks. Confinement to a small cage which encouraged the young pup to sit with his hind limbs spread was shown to reduce the incidence of CHD in genetically susceptible pups.
  
  
• Physiotherapy: Passive flexion and extension of hind limbs over a range of motion and distal to proximal massage helps prevent joint stiffness and reduces wasting of hind quarter muscles.
  
  
• Weight loss is absolutely essential for overweight and obese dogs. (To determine ideal body weight for each breed, consult your vet.)
  
  
• A restricted feeding programme during the rapid growth phase in suspected dogs.
  
  
• Pain control with analgesics: Consult your vet for the appropriate drug and dosage regimen. Do not selfmedicate.
  
  
• Chondroprotectives like glucosamine and chondroitin can be used.
  
  
• Acupuncture/shortwave diathermy/therapeutic ultrasound may give temporary relief from pain.
  
  
• Swimming is also useful – the aim being to build up muscle mass to support the hips.
  
  
• Surgical therapy: Surgery may be necessary if signs are severe and unresponsive to medical therapy or chronic in nature.
  
  
• In young patients, Pectineal myectomy (cutting the pectineus muscle) is an alternative to allow temporary pain relief.
  
  
• Triple pelvic osteotomy (cutting the bones of pelvis, rotating and fixing with special bone plates) are best performed before hip joint changes occur and is performed before the dog reaches skeletal maturity (usually within one year).
  
  
• Total hip replacements are indicated in skeletally mature animals with severe painful disease.
  
  
• Femoral head and neck arthroplasty: Surgical removal of femoral head and neck results in a false joint and pain free movement of hip. Best suited for dogs less than 25 kg. It is a common procedure that can be done with minimal instrumentation and gives good results.

(Dr. S. Ayyappan, M.V.Sc; Ph.D, F.ASIF (Swiss) has a Certificate in Canine Orthopedics (Swiss) and a Post Doc in Veterinary Surgery (USA). He can be contacted at: 9841249129/26475988, e-mail:jujups61@hotmail.com)

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Did you know?

• Canine hip dysplasia was first reported in 1935.
  
  
• It is mostly seen in giant/large breed dogs like German Shepherds, Retrievers, St. Bernards, Labradors, etc.
  
  
• Hip dysplasia can never be cured but clinical signs may be improved or eliminated with medical or surgical therapy.
  
  
• The clinical signs may go through periods of exacerbation or remission throughout the animal’s life.