The term ‘dysplasia’ means abnormal development of a tissue or organ.
What is hip dysplasia?
Hip dysplasia is abnormal development of the hip joint. The consequence of this abnormal development is joint laxity or instability. Affected animals have a normal joint at birth but for some reason the soft tissue support of the joint does not keep pace with the growth of the bones.
The joint becomes unstable and normal weight-bearing leads to partial dislocation. The stretching of the joint capsule/ligament and the abnormal loading of the joint surfaces lead to inflammation, pain, physical abrasion of the articular cartilage and stress fractures in the bone beneath this cartilage. The cartilage damage leads to early and irreversible arthritis. In most cases both hips are affected.
How would I know if my dog has hip dysplasia?
The earliest signs are usually seen between 4 and 10 months of age with stiffness after rest, difficulty getting up from a lying/sitting position and reluctance/inability to exercise (as a result of the discomfort) being most commonly reported. Sometimes a “clunking” sound is heard when the dogs get up/walk. Often the lower back seems rounded or hunched as attempts are made to shift the weight onto the front legs. Typically the feet of the hind limbs are placed close to the midline and affected dogs have a short pottery hind limb gait with swaying of the hips.
How is the diagnosis confirmed?
Manipulation of the hips reveals pain and characteristic instability. Radiographs are helpful to confirm this hip laxity and to show early bony changes/arthritis.
How is the diagnosis confirmed?
Manipulation of the hips reveals pain and characteristic instability. Radiographs are helpful to confirm this hip laxity and to show early bony changes/arthritis.
The following radiographs are of the same labrador and show the progressive nature of hip dysplasia and the subsequent arthritis:
What can be done?
There is unfortunately no way of making affected joints normal. If left, the joints remodel and become stable, but they will be arthritic. Despite this, studies show that over 60% of dogs with hip dysplasia/arthritis will have an active adult lifestyle with little or no requirement for medication. It may take until 18 months of age for the discomfort to subside.
Strict weight control and exercise moderation (little and often) alone are effective in many dogs. Anti-inflammatory medication is required in some cases and where necessary it is best administered only as necessary or intermittently rather than every day. For some dogs the level of discomfort is not satisfactorily controlled with these conservative measures and consideration is then given to surgical intervention.
What are the surgical options?
If a diagnosis is made before the cartilage damage becomes too great (usually 6-7 months of age) then there are surgical techniques that can limit the progression of arthritis (symphysiodesis and triple pelvic osteotomy or “TPO”). In older dogs, total hip replacement is an option and has a very good success rate in dogs.
This surgery is regularly performed at Davies Veterinary Specialists by our veterinary orthopaedics team. Removal of the femoral head (excision arthroplasty) can be performed to eliminate the contact between the arthritic joint surfaces and can give satisfactory function particularly in small breed dogs/cats.
Total hip replacement is considered to be more reliable and effective than excision arthroplasty in medium to large breeds of dog but is more expensive.
When is surgery advised?
Where possible it is preferable to opt for conservative management in the first instance. Weight loss, dietary change where appropriate, regular but controlled exercise (including hydrotherapy), nutritional supplementation (omega-3 fatty acids, glucosamine) and anti-inflammatory painkillers may control the pain whilst the hips develop and stabilise. If this approach is not effective then surgery should be considered.
The success rate for total hip replacement or excision arthroplasty is not affected by the severity of arthritic change which means that there is no pressure to make a hasty decision. In those cases where a diagnosis has been made before significant cartilage damage has occurred, careful discussions will need to take place about the benefits and implications of early surgery.
If you are concerned about the health of your pet you should contact your veterinary surgeon.