Hip dysplasia is a common inherited problem in dogs but it also occurs in other species. It is primarily a disease of large dogs but can be seen in any breed. The hip is a ball and socket joint. Close relationship of femoral head (ball) and the acetabulum (socket) transfers power from the muscles to drive the body forward for maximum strength and speed.
The ball rotates freely within the socket and the bones are shaped to perfectly match each other and are covered by a spongy layer of cartilage. The joint is surrounded by a fibrous joint capsule and contains lubricating oil (joint fluid).
Hip dyspasia is an abnormal development of the joint causing a laxity (or looseness) of the joint. As the joint develops the two bones loose contact with each other so the joint can subluxate or partially move out of the socket. With time the bones become more deformed, the surrounding tissue becomes stretched and the joint becomes progressively unstable and inflammed. Inflammation leads to the body laying down bony spurs and fibrous tissue around the joint, causing progressive osteoarthritis.
The cause of hip dysplasia is multifactorial. It is definitely an inherited disease but can also be influenced by external factors after the puppy is born. Excessive nutrition, obesity and an inbalanced diet can contribute to it’s development. In addition over exercise leading to increased force on the hip joint eg jumping, ball chasing, excessive running can increase the chance of it developing.
Not all dogs will show clinical signs at a young age. Some dogs only show signs of pain and discomfort as the joint progressively deteriorates with age, after periods of confinement or with obesity. Clinical signs range from reluctance to jump, lameness, pain on manual manipulation of the joint, a bunny hopping gait, stiffness when getting up or down, or muscle wastage in the hind quarters.
Clinical signs may be suggestive of hip dysplasia but before a diagnosis is made you must consult your veterinary surgeon. Your vet will need to anaesthetise your dog so he/she is relaxed. Palpation may reveal a degree of hip laxity, but X-rays of hips is the only real method of diagnosis. The xray can show the degree of malformation of the joint and will also highlight the degree of secondary arthritis.
Treatment can be divided into non-surgical and surgical methods:
Aims to alleviate signs and progression of the disease but the deformity and secondary changes will not change significantly.
It is beyond the scope of this article to go into detail but some surgical methods available are:
Prevention of hip dysplasia is extremely important, especially with breeding stock as they have the potential to increase the incidence of the disease. Remember that not all dogs will show clinical signs, so x-ray screening is the only way to determine if dogs have the disease. There are 2 schemes available in New Zealand.
As previously mentioned a good balanced diet avoiding excessive feeding, plus controlled exercise during the first year of life are also extremely important to help prevent this disease.