Hip dysplasia is a painful and devastating condition that primarily affects large breed dogs. Basically, the hip socket and the head of the large femur bone do not fit together properly, causing great pain and lameness. Surgery is often necessary to correct this chronic condition, and in extreme cases the pet may need to be euthanized.
After much research, it was found that hip dysplasia is inherited, passed on from generation to generation. In an attempt to keep track of and reduce the incidence of hip dysplasia, the Orthopedic Foundation for Animals (OFA) was founded in 1966. This non-profit organization was created specifically as an aid to breeders to help reduce hip dysplasia.
Hip dysplasia is diagnosed through radiographs (x-rays) of the hips. By testing dogs before breeding and only breeding dogs that are free of hip dysplasia, the incidence of this disorder has been reduced in several breeds. Unfortunately, not all breeders submit hip x-rays for evaluation and hip dysplasia continues to plague many breeds of dogs.
How Does the OFA Work?
As mentioned, hip dysplasia is diagnosed through x-rays. However, in order to examine the hips properly, the dog must be positioned in a specific fashion. This typically requires sedation or anesthesia. Nearly any veterinarian can take the appropriate x-rays. Once the x-rays are taken, they are submitted to the OFA. At this point, the x-rays are review by three independent veterinary radiologists and the hips are graded. There are currently 7 classifications: excellent, good, fair, borderline, mild dysplasia, moderate dysplasia and severe dysplasia.
It is thought that dogs are born with normal hips and hip dysplasia slowly develops over the course of months to years in affected dogs. By 2 years of age, 95 percent of animals that have the dysplastic genes will show evidence on x-rays. For this reason, final evaluation is not done until the dog is over 24 months of age. Dogs have been evaluated as young as 4 months of age but any dog evaluated before 24 months of age receives a preliminary grade. The final, more accurate, determination of the hips is done after age 2 years. At this point, the dog is typically fully developed and evidence of hip dysplasia should be present.
Dogs that receive an excellent, fair or good rating, are good candidates for a breeding program. Those dogs considered borderline should be re-evaluated 6 months later and not bred until they are re-evaluated. Dogs that rate mild, moderate or severe should not be bred.
The severity of the dysplasia on x-ray does not always correlate with severity of pain or lameness nor does it determine when the pet will begin showing signs of hip dysplasia.
OFA-evaluated hip x-rays are not only for dogs in breeding programs. Owners of any dog, even mixed breed dogs, can request OFA evaluation of their dog's hips. For a cost of around $30, you can have three board certified radiologists examine your pet's hips and let you know whether or not hip dysplasia is going to affect your dog.
For more information on OFA, visit their website at www.offa.org.
Breeds at Risk
Hip dysplasia is typically thought of as a large-breed dog illness. German shepherds, Labrador retrievers, golden retrievers and Rottweilers are some of the more commonly affected breeds. Over time and through the diligence of breeders, the incidence of hip dysplasia in these breeds has been reduced. For example, in 1974, 19 percent of Labrador x-rays were diagnosed with hip dysplasia. In 2000, only 12 percent were dysplastic. In addition to reducing the incidence, the number of x-rays submitted to OFA has continued to increase. In 1974, 713 Labrador x-rays were submitted, and 10,379 were submitted in the year 2000.
Currently, the risk of developing hip dysplasia in German shepherds is 19 percent, in Labrador retrievers 13 percent, in golden retrievers 21 percent and in Rottweilers 21 percent. Of the common large breed dogs, the St. Bernard (47 percent), bloodhound (26 percent), bullmastiff (25 percent), Newfoundland (22 percent) and Chesapeake Bay retriever (22 percent) have the highest incidence of hip dysplasia. Of the smaller dogs, the pug (60 percent) and bulldog (73 percent) have the highest incidence.
When selecting a dog, ask the breeder if the parents have had OFA x-rays of the hips and ask the score they received. If the parents have not had OFA evaluated x-rays, you may want to consider finding a different breeder. Be aware that even though the parents may have excellent hips, it is still possible your pup has inherited hip dysplasia. OFA evaluated x-rays are recommended for your own peace of mind.
For more information, please read the article Hip Dysplasia.