What We Know About Hip Dysplasia in Dogs

Research on canine hip dysplasia (CHD) suggests it is a more complex disease than was first thought.

Hip dysplasia (“bad development”) appears in people and many species of animals. In some breeds of dogs, it is the most common cause of osteoarthritis or degenerative joint disease. Because both humans and dogs get hip dysplasia, dogs made a good subject to use in research. Most of these techniques below are also used on humans.

Research on canine hip dysplasia (CHD) suggests it is a more complex disease than was first thought. There are no simple answers or solutions to the problem.

The complexity of CHD results in research findings that appear to be contradictory. However, many aspects of the disease have been repeatedly and independently documented and are generally accepted by the scientific community. Three important ones are:

  1. Canine hip dysplasia is caused by the presence of many genes (polygenic). Although no environmental cause has been found, many environmental factors contribute to its expression in a particular dog (phenotype).
  2. The only current means for reducing the occurrence of CHD is by selectively breeding for normal hips.
  3. Radiography is the accepted means for evaluating the hip status.

Development

Regardless of what the initiating factor or factors may be, abnormal looseness of the hip joint after 2 weeks of age seems to be the event most commonly reported to result in hip dysplasia. However, there are exceptions to this, and dogs with tight hips have developed hip dysplasia.

The early changes are not easily detected. Severe cases may be diagnosed as early as 7 weeks of age. Others may not show up in radiographs until over 2 years of age.

Breeding

Most inherited traits in animals are polygenic. These traits do not follow patterns based on dominant/recessive pairs because polygenic traits are affected by many genes. Only some puppies will have the same combination of genes for a trait as the parents. Some will have a more desirable combination while others will have a less desirable pattern.

As the number of involved genes increase, the possible outcomes also increase. In addition, remember that it is also possible for different genes to have a different level of influence on the trait, complicating the outcomes considerably.

A dog with excellent hips but with more than 25 percent of his brothers and sisters affected with hip dysplasia probably is a poorer breeding prospect than a dog with fair hips and less than 25 percent of his brothers and sisters exhibiting dysplasia.

The signs of hip dysplasia vary from decreased exercise tolerance to severe crippling.

Clinical Symptoms

According to Hip Dysplasia: A Guide for Dog Breeders and Owners, by E.A. Corley and G.G. Keller:

  • “The signs [of hip dysplasia] vary from decreased exercise tolerance to severe crippling. They include: a reluctance or inability to go up or down stairs, difficulty in rising from a sitting or prone position, bunny-hopping gait when running, stiffness early in the morning that improves as the dog warms up, change in disposition due to pain, lameness after exercise, wobbly gait, a clicking sound when walking, and many others. Many dogs will shift their center of gravity forward in an effort to relieve weight and pressure on the hips. These dogs generally present a front end that appears well-developed relative to the rear end.
  • “In dysplastic dogs, the hip joint is a weakened structure that is more subject to being injured by normal activity such as jumping off a couch, or rough housing with a playmate. Frequently, this results in an acute lameness that in the mind of the owner was caused by the injury, whereas the underlying dysplasia actually made the joint more susceptible to injury. Obviously, the normal hip can be injured, but the radiographic examination can usually distinguish between a hip problem due to dysplasia and one due to other causes.
  • “CHD can not be diagnosed by observing how the dog moves, acts, lies down, etc. The clinical signs may be caused by other problems; therefore, a complete orthopedic and radiographic examination is required before arriving at the conclusion that the signs are caused by CHD.”

Environmental Influences

Environmental factors, such as type of food and exercise in puppyhood, have been shown to affect the displayed symptoms within the same litter. However, subsequent generations from both groups showed the same rates of dysplasia, meaning that although the phenotype may be affected, the genotype is what determines whether a dog has the potential for being affected with hip dysplasia.

In general, low-protein diets and low activity levels through puppyhood reduced the symptoms of hip dysplasia markedly. However, the degree of diet reduction and no activity may or may not be practical for the average person to attempt.

It’s best to keep your puppy from any kind of jumping for the first year or so in life. It’s also best to keep from sustained exercise until at least a year old. Sustained exercise includes: jogging with owner, pulling weights, mushing, running with owner on bike, etc. Even for dogs not at risk of hip dysplasia, it’s wise not to exercise too strongly too early as such exercise may interfere with proper growth of joints, leading to similar problems such as arthritis on the joint or OCD.

Diagnosis of Hip Dysplasia

Any diagnosis of hip dysplasia must be made via expert radiographic diagnosis. This involves taking X-rays of the joint and typically sending the film to organizations that will evaluate, register, and certify the dog.

Veterinarians will often “diagnose” the film themselves, but if the question is critical it’s best to have them properly evaluated (unless, of course, your vet is experienced with radiographic evaluation — not all are).

You cannot make a reliable diagnosis of hip dysplasia on the basis of external symptoms, such as lameness or gait.

Here is a veterinarian with tips on how to exercise a dog with hip dysplasia:

Life for Dogs With Hip Dysplasia

Diagnosis of hip dysplasia is not an automatic death sentence for your dog! Because it is a polygenetic trait, the variability of expression is actually quite wide.

Some dogs may experience little or no discomfort, and you may never know they have hip dysplasia unless you test for it. Other dogs may experience more pain, but it may be easily controlled with proper exercise and judicious use of aspirin under the direction of a vet. Only a small percentage of cases are so crippled by hip dysplasia that they must be euthanized.

You should immediately neuter any dog who has hip dysplasia. The only known means of eliminating this disease lies in well-managed breeding programs, so do your part by eliminating the possibility of your dog contributing to the overall problem.

Discuss with your vet appropriate strategies for dealing with hip dysplasia. In most cases, the general advice is to keep the dog from doing any kind of jumping or causing other sudden stress to the joints.

However, because solid muscle buildup around the joint helps to ease the pressure on the joint, regular exercise is generally recommended, with swimming topping the list as gaining the most benefit with the least stress to the joints.

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