Canine Hip Dysplasia

What is hip dysplasia (HD)?

HD results from the abnormal development of the hip joint in the young dog which usually occurs due to the laxity of the muscles, connective tissue, and ligaments that should support the joint. HD may or may not occur on both sides. Most dysplastic dogs are born with normal hips but due to genetic and possibly other factors such as enviroment and diet, the hip joint does NOT continue to develop normally as the puppy grows and possible sign of difficulty, in movement, possibly pain, begin to appear. The most important part of these changes is that the bones are not held in place but actually move apart, due to change in laxity thus adding instability in the joint. This is defined as subluxation.

What are the symptoms of hip dysplasia?

In severe cases, puppies as young as five months will begin to show pain and discomfort with vigorous exercise (which puppy's are prone to do!) The condition will worsen until even normal daily activities are painful. Without intervention, these dogs may be unable to walk at all by a couple years of age. In most HD case, though, a Dysplastic dogs ppears to be pretty normal until the middle or later years in the dog's life, when problems/symtoms become apparent.

Dogs with HD, in most cases, walk or run with an altered gait referred to as a 'bunny hopping' gait. They will show stiffness and pain in the rear legs after exercise or first thing in the morning, although in minor cases, the mucles and joints warm up and appear to be normal. Some dogs will limp and, through choice, will decrease their level of activity.Some HD dogs will lose muscle tone and may even need assistance in getting up in the latter stages.

What are the risk factors for the development of hip dysplasia?

HD is caused by looseness in the hip joint which creates abnormal wear and erosion of the joint and as a result pain and arthritis develops. In trying to determine why some dogs/bloodlines develop HD while another does not, many folks find themselves surrounded by a much Heated controversy about what predisposes animals to contract the disease. The most popular thought is that HD is strickly Genetic, another thought is that environment plays the highest role. In my years of working with GSD's and through research concerning HD, I believe that the cause of HD in somewhere in the middle with Genetics playing the highest role in creating poor hip structure (which proper breeding can help avoid) with Enviroment exaserbating the problem but not causing HD. Note: In some cases x-rays and arthritic changes suggest HD, but in reality, the x-ray does not show TRUE HD. A dog who has had an accident, say into a hole, might have injured the hip joint badly enough to cause calcification or other problems which would cause the OFA to find the dog with a degree of HD, while in reality, this would not be true! Have you ever broken an arm or leg? The knitted bone usually has changes and possibly may be larger in width in the break area. Does this mean that you had a deformed bone prior? NO! In another known problem, some medications cause the bone and joint to change in color which will cause the OFA to determine a degree of HD. As genetically, the dog was HD free prior, this would be a false finding of true HD and would not cause HD in further progeny. In these instances enviromentment CAN cause arthritic changes skewing true OFA findings, although not commonly found.

Genetics: Genetics play the highest role of determining whether a resulting litter could develope HD. If a parent has HD, then the offspring are at greater risk for developing HD. Although some researchers feel that genetics are the only factor involved, others are adamant that genetics cause less than 25% to the development of the disease. The truth probably lies in the middle. In an HD free bloodline, genetically, then resulting progeny will not contract the disease. But, if the bloodline carries genetic HD, then resulting progeny may contract HD. We can greatly reduce, or increase when dealing with a back-yard-breeder, the incidence of HD through extremely careful breeding, researching each bloodline thoroughly. The other thing to note is that even if both parents are HD free but have HD through the bloodline, HD CAN pop up in later generations unexpectedly to some degree.

Nutrition: The severity of HD, in genetically susceptible animals, can be caused in a number of ways. Obesity is one of the leading contributors to increasing the severity of HD! Think about it! Carrying extra weight will exacerbate the break down of the joint in a dog with HD. Another factor that may increase the incidence is rapid growth in a puppy during the ages from three to ten months. This fact is growing in evidence and many breeders are taking action to help educate puppy owners as to correct growth!

Exercise: Exercise may be another risk factor. It appears that dogs that are more susceptible to HD if they over-exercised at a young age. But! It has also been found that dogs with large and prominent leg muscle mass have a MUCH lower incidence with HD. PROPER and SENSIBLE exercising and maintaining good muscle mass has been shown to actually decrease the incidence of the disease. Moderate exercise is defined as an lower impact exercise with encourages steady strengthening of the muscles, such as running and swimming. Any High impact exercises should NEVER be allowed in a young dog as this applies a lot of force to the joint and possibly damage! This would be ANY form of jumping activities, even Frisbee!

How is hip dysplasia diagnosed?

Diagnosis of hip dysplasia in dogs is usually made through a physical exam and x-rays. Most of the dogs that come in for a determination on the health of their hip joints are not showing physical signs, but needing clearance for being HD free for breeding purposes. The breeder wants to ensure that the animal is not at great risk for passing HD down to his or her offspring. (research of the bloodline is also imperative prior to breeding!) The traditional and most common is OFA testing.

OFA: The method used by the Orthopedic Foundation for Animals (OFA) has been the standard for many years. The OFA was established in 1966, and has become the world's largest all-breed registry. The OFA maintains a database of hip evaluations for more than 475,000 dogs. X-Rays are taken by a local veterinarian under specific guidelines and are then submitted to the OFA for evaluation of hip dysplasia and certification of hip status. Since the accuracy of radiological diagnosis of hip dysplasia using the OFA technique increases after 24 months of age, the OFA requires that the dog be at least two years of age at the time the radiographs are taken. OFA makes several recommendations that the evaluation should not be performed while the female is in heat and that to get the correct presentation and ensure that the muscles are relaxed, the dog be anesthetized for the radiographs. OFA radiologists evaluate the hip joints for congruity, subluxation, the condition of the acetabular margins and acetabular notch, and the size, shape, and architecture of the femoral head and neck. The radiographs are reviewed by three radiologists and a consensus score is assigned based on the animal's hip conformation relative to other individuals of the same breed and age. Using a seven point scoring system, hips are scored as normal (excellent, good, fair), borderline dysplastic, or dysplastic (mild, moderate, severe). Dogs with hips scored as borderline or dysplastic are not eligible to receive OFA breeding numbers. The OFA will also provide preliminary evaluations (performed by one OFA radiologist) of dogs younger than 24 months of age to help breeders choose breeding stock. Reliability of the preliminary evaluation is between 70 and 100% depending on the breed.