Now that you have learned the causes and symptoms of hip dysplasia. Let’s find out if your dog is predisposed or has risk factors to be a likely candidate of CHD.
Hip dysplasia is caused by the subluxation in the hip joint. Subluxation creates abnormal wear and erosion of the joint, which leads to arthritis and pain. Browse through our list of risk factors for the development of hip dysplasia.
Genetics
Hip dysplasia is known to be a genetics disease. When a parent dog has a hip dysplasia then the offspring are at greater risk for developing the same disease. It is important to know the dog’s lineage. If there are no carriers of hip dysplasia in your dog’s lineage then it will not contract the disease. Selective breeding cannot completely reduce the incidence of hip dysplasia. If you breed two dysplastic dogs, the offspring are much more likely to have the disease but the offspring will not all have the same level of symptoms or even necessarily show any symptoms. The offspring (or next generation) from these dogs will be carriers and hip dysplasia will most likely show up in their offspring in later generations. The challenge therefore is to eliminate the disease from a breed or specific breeding line.
Nutrition
The biggest factor that displaces a dog to be genetically prone to hip dysplasia is the amount of calories your bulldog consumes.
Studies have shown that obesity can increase the severity of the disease in genetically susceptible animals. Excess weight will exacerbate the degeneration of the joints in a dog, including the hip. Dogs, also English bulldogs, are born genetically prone to hip dysplasia and are overweight are at a much higher risk of developing hip dysplasia and eventually osteoarthritis.
The likelihood of hip dysplasia is the rapid growth in puppies during the ages from three to ten months. Experiments shows that the incidence has been increased in genetically susceptible dogs when given free choice of food. A study has Labrador retriever puppies fed free choice for three years. It placed them on a higher incidence of hip dysplasia than their littermates who were fed with the same diet but in an amount 25% less than that fed to the free choice group.
A diet having too much or too little calcium or other minerals can result to a detrimental effect on the development of the joint. However, today’s complete and balanced dog foods solve the problem of inadequate diet. The practice of feeding homemade dog foods is popular with dog owners. These types of diets must be carefully monitored for proper nutritional balance including calcium and all other essential minerals.
Exercise
It shows that dogs that are genetically susceptible to the disease due to over exercise at a young age. At the same time, however, we all know that dogs with large and prominent leg muscle mass are less likely to develop the disease than dogs with small muscle mass. It is advised for dogs to exercise and maintain good muscle mass to decrease the incidence of the disease. Moderate exercise strengthens the gluteal muscles such as running and swimming is highly recommended for English bulldogs to help keep the weight at bay. Be cautious though to only introduce exercises that do not apply a lot of force to the joints such as playing Frisbee.
Diagnosis of hip dysplasia
The diagnosis of canine hip dysplasia is typically made from a combination of clinical signs of arthritis and pain, a complete physical exam, and radiographs (x-rays). If a dog is showing physical signs of arthritis, there are usually easily recognized changes in the joint that can be detected on radiographs. In addition, the veterinarian may even be able to feel looseness in the joint or may be able to elicit pain through extension and flexion of the rear leg. Regardless, the results are straightforward and usually not difficult to interpret.
However, about half of the animals that come in for a determination on the health of their hip joints are not showing physical signs, but are intended to be use for breeding. The breeder wants to ensure that the animal is not at great risk for transmitting the disease to his or her offspring. There are two different testing methods that can be performed. The traditional is OFA testing. The other relatively newer technique is the PennHip method.
Orthopedic Foundation for Animals (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 hundreds of thousands of dogs. Radiographs are taken by a local veterinarian using specific guidelines and are then submitted to the OFA for evaluation and certification of the dog’s 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. Because some female dogs experience additional hip subluxation when they are in heat, pregnant or nursing the OFA recommends that the evaluation should not be performed during these times.
To get the correct presentation and ensure that the muscles are relaxed, the OFA recommends that the dog be anesthetized for the radiographs. OFA radiologists evaluate the hip joints for congruity, subluxation, the condition of the acetabulum, and the size, shape, and architecture of the femoral head and femoral neck. Three radiologists review the radiographs and a consensus score is assigned based on the animal’s hip conformation relative to other individuals of the same breed and age. The OFA then places the evaluated dogs into one of seven categories. Normal hips are graded as: excellent, good or fair. If the consensus is unclear the dog is graded as borderline dysplastic. And dogs with obvious radiographic signs of hip dysplasia are graded as: mild, moderate, severely dysplastic. Dogs with hips scored as borderline or dysplastic (mild, moderate, severe) 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.
Pennsylvania Hip Improvement Program (PennHIP)
The diagnostic method used by the University of Pennsylvania Hip Improvement Program (PennHIP) uses unique radiographic views of the dog’s hips to more accurately identifies and quantify joint laxity. This program was conceived in 1983 and became a usable system by 1993. To assure quality and repeatability among diagnostic centers using the PennHIP technique, veterinarians must take a special training course to become certified. Radiographs of the hips are taken with the dog under heavy sedation. These radiographs can be taken on a dog as young as 16 weeks. Two views are obtained with the hind limbs in neutral position to maximize joint laxity. These are known as the distraction and compression radiographic views. Weights and an external device are used to help push the head of the femur further into or away from the acetabulum. The amount of femoral head displacement (joint laxity) is quantified using a distraction index or DI. The DI ranges from 0 to 1 and is calculated by measuring the distance the center of the femoral head moves laterally from the center of the acetabulum and dividing it by the radius of the femoral head. A DI of 0 indicates a very tight joint. A DI of 1 indicates complete luxation with little or no coverage of the femoral head. A hip with a distraction index of 0.6 is 60% luxated and is twice as lax as a hip with a DI of 0.3. A third radiographic view is taken using the same positioning as the OFA. The “hip-extended” view is used to obtain additional information regarding the possible presence of degenerative joint disease (DJD) in the hip.
When the PennHIP DI was compared to the OFA scores for 65 dogs, all dogs scored as mildly, moderately, or severely dysplastic by the OFA method had a DI above 0.3.
Hip laxity as measured by the DI is strongly correlated with the future development of osteoarthritis. Hips with a DI below 0.3 rarely develop osteoarthritis. Although hips with a DI above 0.3 are considered “degenerative joint disease susceptible,” not all hips with a DI greater than 0.3 will develop osteoarthritis. It is known that some hips with radiographically apparent laxity do not develop osteoarthritis. A means of differentiating lax hips that develop osteoarthritis from those that will not is important in developing a prognosis and making treatment or breeding recommendations. In one study, the DI obtained from dogs at four months of age was a good predictor of later osteoarthritis, though the 6 and 12-month indices were more accurate.
The PennHIP method has gained popularity and more and more veterinarians are becoming certified.