Hip dysplasia is the abnormal development of the hips. Puppies are born with normal hips, but some then develop abnormally resulting in a deformity of the hip joint.
The deformed hip joint is less stable than a normal one, and later in life, arthritis develops as an attempt by the body to stabilise the joint. The hip joint is made up by the femur (thigh bone), and the pelvis. The femur joins the pelvis by a ball and socket arrangement, the socket formed by the pelvis, which surrounds the ball, or head of the femur.
In a dysplastic joint, the head of the femur is incompletely encompassed by the pelvis, which results in a loose joint. This is called a subluxation. The degree of deformity varies tremendously among affected dogs, but unfortunately, the degree of deformity does not correlate very closely with the symptoms that the affected dog displays.
What are the Symptoms?
We can arrange the symptoms of hip dysplasia into two groups:
- Symptoms affecting young growing dogs
- Symptoms affecting adult dogs
In young dogs, the major symptoms are pain and lameness. The typical case is a large or giant breed dog, about 7 or 8 months old which resents being touched around the hindquarters. He may suddenly become reluctant to walk very far.
Lameness affecting both hind legs is common, but it is more usual for the dog to swing its hind legs forward as it walks, resulting in a ‘wobble’ when watching the dog walking from behind.
This can be quite subtle, and people are frequently unaware that the dog is not moving his hind legs properly. Other dogs walk or run with a ‘bunny hopping’ motion, where they are trying to move the hip joint as little as possible.
Some dogs compensate for sore hips by shifting their weight forward onto their front legs, creating the false impression that the dog has a fore-limb problem. There may also be difficulty in rising from a lying position.
Many cases of hip dysplasia go unnoticed as pups, and for many years the dog walks perfectly normally. Then, in later life, often not until 6 or more years of age, the dog develops a ‘stiffness’, especially on rising, which may go away after a few minutes.
This is because arthritis has developed in the hip joint, and we now properly call this condition ‘hip arthritis’ rather than hip dysplasia.
Hip arthritis is very common in older large breed dogs. The severity varies enormously between dogs. Some have only mild stiffness, which disappears within a few minutes in the morning. Others are severely lame, having difficulty walking for only even short distances.
Most dogs fall somewhere between these extremes, but especially in the early stages, the usual presentation is a dog with a lameness which disappears on exercise. After resting, especially after heavy exercise, the lameness becomes much worse.
Why Does Hip Dysplasia Occur?
There are two major factors in the development of hip dysplasia: genetics and environment.
Most people are familiar with the concept of an inherited disease, where one individual acquires a disease from a similarly affected parent. Hip dysplasia is an inherited disease. Unfortunately, it’s not that simple though.
Not all dogs which are genetically affected by hip dysplasia go on to develop the disease. Secondly, not all dogs with hip dysplasia are lame and many live perfectly normal lives even though they have dysplastic hips. This has important implications for breeding dogs.
No-one is certain why a dog which has inherited hip dysplasia from its parents doesn’t go on to develop the disease. So we introduce another factor which we loosely call the dog’s “environment” to try and explain this. However, there are two significant things which do seem to play a part: diet and exercise.
Diet – Overnutrition, especially of calcium, phosphorus and calories is believed to play a part. Most people with large breed puppies want them to be big.
That’s fine, but if large or giant breed dogs are pushed too hard, by overfeeding or by giving excessive mineral intake, then growth and development will not proceed correctly and hip dysplasia can result.
Exercise – The abnormality in hip dysplasia is a loose joint. A pup that uses his loose joints excessively, can result in the sensitive cartilage ends of the bones rubbing together abnormally, damaging them. This causes pain and starts the process of arthritis, which is an attempt by the joint to stabilise itself. By restricting the amount of exercise that the puppy has, you can limit the development of hip dysplasia.
Other environmental factors – There is little doubt that this is not the whole story, and that there are more, as yet undiscovered factors influencing the development of hip dysplasia.
It is important to remember that:
- Not all dogs with hip dysplasia have parents with hip dysplasia.
- Just because a puppy’s parents have hip dysplasia, it is not inevitable that the puppy will develop hip dysplasia.
How you can give your pup the best chance of healthy hips
Despite the development of hip scoring schemes in many countries, canine hip dysplasia is still a very real problem in many breeds of dog.
Although you cannot alter the limits of the potential, for developing good hips, inherited by your pup, you can help your puppy to grow the very best hips he can, within the limits of those genetic boundaries.
Not so long ago, a roly-poly plump puppy was considered ideal. The extra fat was there to sustain him if he ever fell ill, and this ‘puppy fat’ was considered cute and harmless. Extra weight on a puppy, especially large breed puppies, is now considered to be a real risk factor for hip dysplasia.
Whilst it is true that a puppy who has not inherited any hip dysplasia genes will probably come to no harm from being plump for a few months, there is no way of knowing for sure what genes your puppy has inherited. To be on the safe side, therefore, it is a good idea not to let your puppy get fat, or to grow at too fast a rate. If you are unsure how much to feed your puppy, or whether or not he is too fat or too thin, consult your veterinary surgeon for advice.
It is also likely that excessive exercise or frequent impact of small puppy legs onto hard surfaces like concrete, or as a result of jumping, may reduce the chances of the puppy growing the healthiest hips possible. Lifting your puppy on and off high surfaces, and restricted his exercise to short informal romps as opposed to long marches is definitely to a good idea.
If you are unsure how much exercise to give your puppy or worried about his hips or any other aspect of his health, please consult your veterinary surgeon for advice.