Disease and Illnesses of dogs – Hip Dysplasia
“Dysplasia: The abnormal growth or development of cells or a tissue such as bone”
A normal hip joint is a ball and socket where the rounded end of the femur fits into a cup of bone on the pelvis called the acetabulum. The joint is stabilised by ligaments within the joint and a capsule around it. The ends of the bone are covered in smooth cartilage so the joint moves smoothly, freely and without pain.
A dysplastic hip has loose ligaments which makes the joint unstable. The joint does not fit together as it should, the ball sits slightly out of the socket and this is called subluxation. Over time the joint surface becomes damaged and misshapen and the cartilage wears away. This results in arthritic changes and pain when moving the joint.
What are the symptoms of Hip Dysplasia?
The signs of hip dysplasia are similar to signs of arthritis in the hips present for any other reason and mainly relate to pain in the hind limbs. The signs can start to show at any age with particularly severe disease noticeable in quite young puppies. Symptoms will become progressively worse without intervention and appropriate treatment. They include:
Stiffness in the hind limbs, especially when rising from rest
Reduced range of movement in the hind limbs
Lameness in one or both hind limbs
Abnormal gait where the dog may “bunny hop” on the hind limbs
Avoiding or inability to climb stairs or jump into the car
Which dogs are susceptible to Hip Dysplasia?
Hip Dysplasia is primarily a disease of larger, pure bred dogs but can also be seen in medium sized dogs and crossbreeds. It is rarely seen in small breeds of dog.
Hip Dysplasia is an inherited condition and some breeds of dog are genetically predisposed. These include: Labradors, Golden Retrievers, German Shepherd dog and Rottweilers.
As mentioned above, hip dysplasia is an inherited condition so it can be reduced in predisposed breeds by selective breeding. This involves screening both bitches and dogs that are intended for breeding. This is done by taking a standard set of x-rays of the hips once the dog is skeletally mature. These x-rays are sent off to an expert panel, assessed for signs of hip dysplasia and given a score. Animals with a good hip score are suitable for breeding but it is not advisable to breed from animals with poor hip scores as their offspring would be likely to suffer also.
Hip dysplasia is exacerbated by obesity as the heavier the dog is, the more force is being put through the joints. A healthy weight should be maintained with a good diet and regular exercise. Minerals such as calcium are also very important in forming healthy bones. Good quality commercial diets will be well balanced but care should be taken when feeding home cooked diets.
Exercise is important to increase strength and muscle mass which helps to stabilise the hip joint as well as helping to control weight but it is thought that too much exercise at a very young age may damage the bones. Exercise should be done every day as opposed to just one long walk at weekends and low impact exercise such as swimming is ideal.
How is Hip Dysplasia diagnosed?
As mentioned above, hip dysplasia is often detected in routine screening of animals that are destined for breeding. Otherwise, a history involving the clinical signs mentioned above will alert your vet in combination with clinical examination. The vet can often feel looseness in the joint and can sometimes feel that range of movement is reduced and the animal seems to be in pain when the hips are extended. X-rays will confirm the suspicions.
How is Hip Dysplasia treated?
There are three main surgical treatments for hip dysplasia:
1) Triple Pelvic Osteotomy (TPO): This is used in cases where the ligaments in the joint are loose but there is not yet any damage to the joint itself. It involves surgically breaking the pelvis and realigning it so the ball and socket joint fits together better and the joint can move smoothly.
2) Total Hip Replacement (THR): This can be used in cases where there is severe damage to the joint surface. It involved removing the entire joint and replacing it with a prosthetic joint which restores smooth, pain free movement of the joint. A dog with prosthetic hips in both hind limbs is shown in the x-ray below;
3) Femoral Head and Neck Excision (FHNE): This is a salvage procedure which involves cutting out the ball on the top of the femur and letting the body form a false, fibrous joint. This is pain free but stability and range of movement of the joint are not ideal.
Weight - As mentioned above it is important to control your dog’s weight, especially in cases of hip dysplasia. Any overweight dog diagnosed with hip dysplasia should be put on a regime of gentle exercise and a diet. Exercise such as swimming or hydrotherapy is ideal as is doesn’t put excessive force through the joint and helps build up muscle mass without further damage to the affected joint.
Supplements – Glucosamine is a glycosaminoglycan which is a building block of cartilage and Chondroitin protects cartilage from damaging enzymes. Together they are very helpful in slowing the progression of arthritis as a result of hip dysplasia. They maintain the cartilage on the joint surface and this helps the joint to keep moving smoothly and without pain. They are available in several forms such as Seraquin, Flexadin and Cortaflex.
Non Steroidal Anti-Inflammatories (NSAIDs) – These are a family of drugs that reduce inflammation in and around the joint and act as pain killers. They are safe for long term daily use to control the pain associated with hip dysplasia and can make a big difference to your pet’s quality of life. There are several different drugs that can be used: Metacam (meloxicam), Rimadyl (carprofen) and Previcox (firocoxib) are some of the most common.