Hip dysplasia
by Professor John Innes
RCVS Specialist in small animal
surgery (orthopaedics)
What is hip dysplasia?
Hip dysplasia is a common developmental disease of the hip. As a puppy
grows the soft tissue support for the hip may become loose (lax) and this
can allow the head of the femur (the ball of the ball and socket joint)
to slip in and out of the acetabulum (socket). This abnormal laxity of
the hip can damage the tissues of the joint leading to osteoarthritis.
Below - a radiograph showing severe hip dysplasia
notice how the head of the femur is not fitting well in to the acetabulum
What sort of dogs are affected?
Hip dysplasia occurs most commonly in medium-large breed dogs of any breed.
Some breeds are commonly affected whereas others are rarely affected (e.g.
Greyhound). However, hip dysplasia can occur in smaller dogs and also sometimes
in cats.
What causes these diseases?
The cause of hip dysplasia is not fully understood. Certainly there is
a complex genetic basis and it is likely that several different genes are
involved. It is also likely that environmental factors (exercise, growth
rate, nutrition) play a role and obesity will worsen the condition. At
Liverpool we are investigating the genetic basis of the disease in collaboration
with colleagues at CIGMA at the University of Manchester.
What are the signs of these diseases?
Hip dysplasia can cause pain and lameness although in some dogs the disease
may remain clinically silent for many months or years. Often in puppies
there is a swaying hindlimb gait and some dogs may sit down at exercise
because of the discomfort. Usually the condition occurs in both hips and
so signs may relate to joint stiffness in both hindlimbs. Later in life,
the osteoarthritis initiated by hip dysplasia may progress to cause pain,
stiffness and lameness.
How are these conditions diagnosed?
A clinical examination by a veterinary surgeon is the first step in diagnosis.
Certain clinical tests can indicate if hip dysplasia is present but it
may be necessary to perform these tests under heavy sedation or anaesthesia.
If hip dysplasia is suspected, radiographs (x-rays) such as the one above
are the most usual initial step in making a diagnosis.
What can be done to treat the condition?
The treatment of hip dysplasia in young dogs is controversial. Certainly
only those dogs that have disability should be treated - many dogs with
hip dysplasia never need treatment. Conservative treatment involves exercise
restriction and possibly pain-relieving medication and can be very effective.
As an affected dog matures the pain associated with hip dysplasia can subside
although the hip will be prone to osteoarthritis which may cause stiffness
and pain in later life. Some veterinary surgeons advocate surgical treatment
in puppies. In older dogs where the osteoarthritis of the hip is causing
intractable pain that does not respond to medical treatment and weight
loss, one might consider a total hip replacement. This operation is similar
to that performed in people and can relieve pain and provide excellent
function. Careful specialist evaluation of the dog is required prior to
such a surgery. At Liverpool we use the Biomedtrix
canine hip system, which is probably the most widely used hip system for
dogs in the world today.
