Hip Dysplasia in Dogs

One of the most common conditions in veterinary practice, and one that I quickly learned to caution prospective puppy owners about, is hip dysplasia. It is a term you come across often when you are looking at adopting a large or giant breed puppy or adult dog, but not necessarily always explained. I will do my best to cut through all the medical terms, and describe what it is and how it is treated.

When your veterinarian encourages you to give your puppy three meals a day of a good quality food, he is not saying that to make your life difficult and put extra strain on your wallet, or even to make an extra buck out of you, but to ensure your puppy grows at the right rate, and doesn't eat too many nutrients at any one time that can cause rapid weight gain and growth and ultimately hip dysplasia. There are many chain reactions that can occur, should your puppy develop at a faster pace than normal. Excess nutrients leads to rapid growth and weight gain, which means that the hip joints don't develop properly, and this (plus the extra weight) places strain on the ligaments and muscles surrounding the hip joint and causes dysplasia in later years (or as early as five months in severe cases), but I'm getting ahead of myself. Let me explain what hip dysplasia is first, and then we'll worry about what causes it!

To understand what hip dysplasia is, it is first necessary to explain how the hip joint works. The leg bone, or femur, forms a ball at the top, which slots into the socket, or acetabulum, in the pelvis and so joins the hind leg to the rest of the body. A strong ligament connects the femoral head (the ball) to the acetabulum (the socket), and the two are surrounded by a band of connective tissue which forms the joint capsule and stabilizes the joint. Both the ball and the socket are cushioned with cartilage, and the joint contains a thick, gooey fluid that lubricates the joint. All these factors combine to form a normal joint.

When a puppy is genetically predisposed to hip dysplasia, or that whole chain reaction of rapid growth occurs, the ball and socket don't meet as snuggly as they should and there is instability in the joint; in other words, it moves around more than it should - medical experts call it subluxation. This movement (subluxation) causes a dramatic change in the size and shape of the joint by wearing the cartilage. As the cartilage wears, bone spurs (osteophytes) are formed and the joint capsule thickens which results in osteoarthritis and is the first sign of degenerative joint disease - in other words, it can only get worse.

The first signs of hip dysplasia are lameness, pain and discomfort during and after exercise. Many times dogs will run with a "bunny hop" gait, where they use both hind legs at the same time to minimize the weight placed on the affected leg. They will show pain and stiffness in their back legs when they rise, and may have difficulty climbing stairs. In milder cases, exercise will warm the joint up, and stiffness will dissipate. Many owners think this is just part of the natural aging process, and are surprised, when they start treatment, to see an improvement in their pet's movements. As the condition worsens, dogs will lose muscle tone, and may even need help getting up.

OK. So now that we understand what hip dysplasia is, who is more likely to get it, and why? Hip dysplasia is most common in large and giant breed dogs, though some cases have been seen in medium breeds (like Spaniels and Shetland Sheepdogs), and very rarely in small breed dogs. Research shows that incidents of hip dysplasia are seen most often in German Shepherds, Labrador Retrievers, Golden Retrievers, Rottweilers, Great Danes and St Bernards, but as these breeds are very popular, it stands to reason that more incidents will have been noticed as there are simply more of these dogs around. A dog that has hip dysplasia in its family line has a genetic predisposition to the disease. It does not necessarily mean that it will show symptoms of the condition, but it may carry the gene on to its descendants. For example, a puppy born to a litter where the mother or father (or both) has hip dysplasia has a greater chance of developing the condition than one whose parents do not have it. There is no guarantee that the pup will develop symptoms, however its litter mates might develop symptoms in varying degrees. It will, however carry the gene, and will pass it down to future offspring who may or may not develop symptoms, and so on.

Weight plays a large factor in the severity of symptoms. If a dog is genetically predisposed to hip dysplasia, and is also overweight, it is more likely to develop symptoms as the extra weight places undue stress on the joints. Feeding a diet that has too little or too much calcium to a puppy affects the way the joints develop. With nutrition the way it is, this is a less likely cause nowadays, but can still occur where owners elect to cook for their pups themselves or to feed the BARF diet. In these cases, special care should be taken with calcium supplements.

Exercise also plays a role. Hip dysplasia incidents increased where puppies were over-exercised. It is important to get the correct balance of exercise. Jarring games where the puppy is encouraged to jump like playing Frisbee, places undue stress on the joints, while running, walking and swimming (in moderate amounts) strengthen the muscles and may prevent symptoms later on.

There are several surgical treatments for dogs with hip dysplasia:

- The Triple Pelvic Osteotomy is performed in puppies ten months and younger who present symptoms, but have as yet no damage to the joints. The pelvis is broken, and the femoral head is realigned in the acetabulum. It is a very expensive treatment, but extremely successful.

- Juvenile Pubic Symphysiodesis is a less invasive procedure than the Triple Pelvic Osteotomy, though it's more of a mouthful! It has to be done before the puppy reaches twenty weeks of age (preferably at sixteen weeks), and involves fusing two pelvic bones together (before they would have fused naturally). This changes the angle of the hips, and improves the seating of the femoral head in the acetabulum.

- A Total Hip Replacement is the best option for dogs that have already matured and have joint damage. The existing joint is removed, and replaced with an artificial joint made of metal and polyethylene. It is, like the Triple Pelvic Osteotomy, a very expensive procedure, but one where the results are remarkable. Dogs return to a near normal state with no pain.

- Femoral head and neck incision is an option for owners who cannot afford the expense of the total hip replacement. The femoral head (the ball) is removed. The bone then develops a fibrous tissue that acts in a similar way to cartilage. Recovery may result in a less but not completely pain-free existence. Non surgical treatments include the use of Glucosamine supplements and a non-steroidal anti-inflammatory to help reduce pain and inflammation.

So, when you go to choose your next puppy, or consider adopting an adult dog, ask for the results of any screening tests and hip evaluations done. Watch your dog's weight and encourage exercise. It can go a long way to ensuring your pet lives a happy and relatively pain-free life.

Bruno is blogging about Pomeranian and Mops (pug dogs) at Hundefeber.no.

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