This information is provided by Provet for educational purposes only.


Note for Pet Owners:
Hip dysplasia is a condition that frightens many owners although in truth most dogs can live a normal, productive and otherwise healthy life - even with quite severe hip disease present. There is evidence to show that the severity of the changes in the hips (as seen on an XRay) is not directly related to the amount of pain shown by an animal. Nevertheless, hip dysplasia can be a debilitating disease and there is a strong hereditary influence - so responsible owners and breeders should have their animals screened by their veterinarian, and avoid breeding from the worst affected individuals. The occurrence of hip dysplasia can be reduced by not breeding from affected animals.

For more information about the BVA/KC Hip Dysplasia Scheme in the UK email info@provet.co.uk 

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Hip dysplasia occurs when there is insufficient stability to keep the head of the femur (the "ball") within the acetabulum (the "socket") of the hip joint. This may be due to stretching of the joint capsule or weakness in the surrounding muscles, or a failure of the "socket" to develop properly. Because of this instability the hip joint develops abnormally, remodelling of the bones occurs and new bone is deposited around the joint (used to be called arthritis - now called degenerative joint disease). The result is hindleg weakness, pain and functional disability.

It may surprise people to learn that the cause of hip dysplasia is not known ! Hip dysplasia is a complex (called polygenic or multigenic) disease with many factors involved in the cause. The most important are genetic and environmental factors but, based on detailed analysis of inheritance in German Shepherd dogs the disease is only described as being moderately heritable in that breed. 

Contributing factors are :

Breed - genetic inheritance, BUT specific genes not yet identified. Also multiple genes involved (polygenic).

Body size -  low prevalence - ancestral dog size; greater prevalence -large/giant breeds

Body type - low prevalence - slender and fit. Low subcutaneous fat content (1-2%); greater prevalence- giant breeds, heavy conformation, with acromegaly. Relatively high subcutaneous fat content(5-10%).

Growing pattern - rapid growth rate and excessive weight gain (above the average for the breed) can both increase the likelihood of hip dysplasia occurring.

Increased activity has been associated with increased likelihood of developing hip dysplasia. Possibly increased activity exposes the animal to increased chance of injury, or to excessive biomechanical forces which alter the stability of the hip joints.

Muscle disorder - a muscle disease (developmental myopathy of the pectineus muscle) has been described in German Shepherd puppies with hip dysplasia, but a direct link between the two conditions was not proved, though it may have been present.

Hormone - experimentally a female hormone (the oestrogen relaxin) can induce hip dysplasia due to relaxation of supporting ligaments in dogs, including greyhounds. However there is no evidence of a naturally occurring role for the hormone in the cause of the disease.

Diet does not seem to be important except when excessive calorie intake occurs resulting in too rapid a rate of growth or excessive weight gain. There is good evidence that too high calcium intake may results in skeletal developmental problems, which may include hip dysplasia.

Breed Occurrence
Hip dysplasia affects humans (1.3 children in every 1000) and ALL domestic animals including cats and dogs. Body size is an important factor and one of the of the highest prevalence's of the disease is in large and giant breeds of dog in which over 30% of some breeds may be affected. The disease is less common in dogs with a body size similar to the ancestral dog and it is rare in undomesticated animals.

In the USA screening XRays have indicated that in some breeds over 20% are affected by hip dysplasia including - in descending order : St Bernards (43.2%), Newfoundlands (39.9%), Bullmastiffs (34.5%), English Setters (32.1%), Gordon Setters (32.1%), Old English Sheepdogs (29.9%), English Springer Spaniel (27.3%), Akita (27.1%), Chesapeake Bay Retriever (25.7%), Golden Retriever (27.5%), Norwegian Elkhound (25.6%), Rottweiler (25.4%), the German Shepherd Dog (25.1%), Giant Schnauzer(24.2%), Standard Poodle (23.6%) and the Brittany Spaniel (22.4%). (Reference Riser WH et al J Am Vet Med Assoc (1974) 165:79). Other breeds are over-represented in other schemes eg in the UK the Clumber Spaniel has the second worse breed mean scores (42) in the BVA/Kennel Club scheme (2001)

Dogs less than 30.5 cm in height and less than 11.3 kg in body weight rarely develop hip dysplasia.

It is interesting to note that hip dysplasia is extremely rare in racing greyhounds, but it is seen frequently in greyhounds kept as pets. This highlights the fact that environmental factors are important as well as genetics.

Equal numbers of males and female dogs are affected with the hip dysplasia.

The disease affects young animals and dogs are usually aged between 5-12 months when signs are first noted. 

Signs include a swaying hindleg gait, hindleg lameness, muscle wastage around the hindquarters, reluctance to exercise, fatigue during exercise, inability to climb stairs or jump up. Sometimes there is a loud "click" heard during exercise. Occasionally affected animals walk in a hunched-up manner with an arched back. In some cases (the worst cases) the dog will wince with pain when it moves it's hindlegs.

It is important to realise that the occurrence of pain is not directly related to the degree of abnormal change that can be seen on XRays.

Remodeling of the hip hip joint can lead to severe deformity. In addition the instability results in new bone being deposited around the joint - this can lead to pain, and reduced range of movement. With advancing age, as degenerative joint disease progresses in the hips, ambulatory  function  is gradually lost resulting in great difficulty rising from a lying down position or negotiating steps and stairs. In large and giant breeds of dogs an inability to jump up (into cars for example) can present serious management problems for owners.

Post-operative complications can occur - particularly following the removal (excision) of a femoral head and neck.

Hip dysplasia is diagnosed from the presenting history, physical examination and is confirmed by taking XRays of the hip joints. For accurate interpretation of the XRays the position of the animal is critical and in order to position the animal correctly (lying on it's back)  it is necessary to immobilise the patient. This usually requires the administration of a general anaesthetic.

This dog has severe hip dysplasia with secondary arthritic changes- some of which are described below 

Abnormal, square shaped head to the femurs with a broader than normal neck. The head "ball" is not lying properly in the acetabular fossa

B There is a lot of "new" bone around the joints such as this osteophyte lying in front of the acetabulum

C There is a loss of cartilage on the surface of the joint resulting in a loss (or narrowing) of apparent joint space between the head of the femur and the acetabulum

D There is an increase in the radiodensity of the bone lying under the acetabulum articular surface. This gives the bone a very white colour - and is called sclerosis. In addition, the joint space (darker line)  appears to be wider because the head of the femur is partially lifted out of the socket created by the acetabulum.

E New bone can be deposited all around the joint, including along the neck of the femoral head.

In young animals genetically predisposed to develop hip dysplasia they should be reared in a cage with minimal exercise as this has been shown to reduce the likelihood of dysplasia developing.

Food intake should be restricted during growth to avoid too rapid a growth or excessive weight gain.

Medical treatment involves the administration of pain killers  and rest. Aspirin and other non-steroidal anti-inflammatory drugs can be very successful , but they do have potential side-effects if used over a long period of time. Corticosteroids can also give a clinical improvement but most authors advise that they should be used with caution..

Surgical intervention is possible in young dogs with acute pain - various techniques can be used in an attempt to increase the stability of the hip joint. 

  • Triple osteotomy of the pelvis to increase the surface coverage of the femoral head (the "ball") by the acetabulum (the "socket")
  • Total hip replacement
  • Removal of the femoral head and neck (excision arthroplasty)
  • Changing the angle of the head of the hip - corrective osteotomy
  • Myotomy - sectioning the pectineus, iliopsoas or or gluteal  muscle or muscle attachments  to provide pain relief

The prognosis is good for most animals, but as they get older the degenerative joint disease makes locomotion more and more difficult

Screening Programmes
There is no doubt that owners should only breed from "normal" dogs and attempt to reduce the numbers of affected animals in those breeds known to develop hip dysplasia on a regular basis.

Controlled breeding of German Shepherd dogs in Sweden and of a colonies of German Shepherd dogs  in the USA have suggested that breeding only from dogs with normal hips can reduce the incidence of hip dysplasia to less than  half - from 39% to less than 17%. However , in a report publish in January 2000 the value of existing schemes has been questioned. HD Update

In many countries there are highly sophisticated scoring systems by which the degree of hip dysplasia can be assessed. In the UK the British Veterinary Association in conjunction with the Kennel Club run a scheme and further details can be obtained from your veterinary practice - or by writing to the BVA/KC Hip Dysplasia Scheme, 7 Mansfield Street, London, WIM OAT.

If you are an owner and would like more information about the UK Scheme Provet will be please to send it to you e-mail info@provet.co.uk 

If you are a veterinarian and would like more information about the UK scheme Provet will be please to send it to you e-mail info@provet.co.uk  


Updated October 2013