Hip Committee Report |
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Hip Dysplasia in Border Collies Everyone wishes that there were no genetic problems lurking in the dogs we breed, sell and buy. However, the reality is that, whether we know it or not, there are genetic flaws in every dog. One of the hardest genetic problems for everyone to deal with is Canine Hip Dysplasia (CHD). The Orthopedic Foundation of America (OFA) data on Border Collies from the 24-year period from 1974-1998 shows a CHD incidence of 12.l% in the films submitted to them for evaluation. Given that many, if not most, hip x-rays are screened for favorable OFA ratings by the dog owners' veterinarians before submission to OFA, a reasonable person might conclude that the actual prevalence of CHD in Border Collies is twice that figure. At this rate one out of every four or five Border Collie puppies will develop CHD; and some of them will need medical attention which can range from dietary supplements to total hip replacement. Why do dogs have hip dysplasia? Is it a disease? Is it inherited? Is it environmental? Are the human breeders of a dog with hip dysplasia to blame? Can breeders do anything to reduce the number of dysplastic dogs? Is the way a dog is brought up important in developing normal hips? How much can the ABCA do to curb Canine Hip Dysplasia? Many of the brightest and the best minds have been trying to crack this intractable puzzle for more than 30 years. There are no guarantees and no quick fixes. Foundation breeders of working Border Collies generally agree that excellence in herding ability is far and away the most important and difficult goal of breeding Border Collies. Factoring in what makes a dog stay sound for its lifetime of hard work is one element in reaching that goal. The condition's name has two parts: dys and plasia. "Dys" (bad) is not the same thing as "dis" (not). The prefix "dys" means bad or abnormal. "Plasia" refers to forming, changing, growing, molding, developing. Think of the condition as an abnormal or bad development of the hip joint. When a badly formed joint starts to degenerate after a period of time ranging from a few months to many years, the dog has the disease called Canine Hip Dysplasia. Joint problems are not limited to dogs. All animals, including humans, can have badly formed hip joints. When one or more of the following, a bad fit, poor cartilage quality, poor muscle strength or a weak ligament, allow wear and tear on the joint so bone rubs on bone, remodeling of the bones takes place which can be so painful that it restricts free movement. Humans call it osteoarthritis and it has become a problem for that individual. Is CHD inherited or environmental? In a word, "Yes." There is an inherited component because the shape of the hip joint, the quality of the cartilage, the potential muscle mass, and the connecting ligament is as much a product of the dog's genes as is the shape of its skull. There is also an environmental component in which CHD can be aggravated or suppressed. There is a huge range of possible hip formations. The two parts of the hip joint can fit together perfectly or they can be practically disunited, or anything in between. If the shape of the socket (the acetabulum) is shallow with rounded edges and the top of the leg bone (head of the femur) is shaped so it makes poor contact with the socket, the hip has bad formation (dysplasia) and will very likely develop painful Degenerative Joint Disease (DJD) no matter how carefully the puppy is brought up. If, however, the socket is cup shaped and almost half of the head of the femur is seated inside it, how the puppy is brought up can influence whether the puppy's hip joint becomes diseased. Finally, if the shape of the socket is a deep cup with a strong rim and more than half of the head of the femur fits snugly inside it, the hip joint could probably withstand environmental stresses and not develop painful degenerative joint disease. Many people want to know if breeders are responsible for canine hip dysplasia. Are they? The production of a puppy and its development into a dog has two parts: the breeder determines which sire and dam provide the puppy's genes and the nurturing actions of the persons bringing the puppy up can influence the expression of those genes. There is not one "hip gene." The complex hip joint is determined by many genes (polygenic), half from the dam and half from the sire. The better the hip joint of both parents, the better are the chances of a good hip joint in the puppies. However, the many genes involved combine in random ways and two dogs with good hip formation can produce a puppy with terrible hips. Still, it is likely that most of their puppies will have better-than-average hips. General advice to dog breeders is to use at least one of the accepted radiographic ways to evaluate hip formation of all breeding animals and to gather radiographic information about as many of the dogs in the potential breeding pair's pedigrees, including their siblings and offspring, as possible. The more dogs having good hip formation in the pedigrees, the better the chances of puppies with normal hips. The only way a dog's hip formation can be evaluated is through x-rays. It cannot be checked by observation and a veterinarian cannot tell by feeling the joints. A veterinarian experienced in taking hip x-rays knows how to position the sedated dog's legs to get an accurate picture of its hip formation. Usually, canine orthopedists have more experience interpreting hip x-rays than veterinary generalists. Does this let the puppy buyer off the hook? Not really. The puppy buyers can ask about hip-evaluation history in the parents' backgrounds. If the breeder makes use of the Orthopedic Foundation of America (OFA) the ratings of all the normal-hipped dogs in the pedigree will be listed on OFA's web site. As some buyers of puppies from working backgrounds seem to expect a guarantee that the dog will have no genetic problems, it is certainly something to be discussed before the puppy departs for its new home. Now the puppy is home with the new owner where the environmental part of hip development continues. Studies have shown that puppies which are grown slowly and kept from rough physical activity have improved chances of normal hip development in borderline cases. This is because puppies which are kept lean and given good quality, lower protein adult dog food experience a more appropriate growth rate of their bones, ligaments and cartilage. The type of activities puppies engage in also contribute to its hip development. During the first year or two it is recommended that rough play, excessive jumping, quick stops and turns, exercise on hard surfaces, and romping with bigger dogs be limited, as wear and tear like this may cause injury and remodeling of the hip joints. Now we come to the ABCA. What, if anything, can a breed registry do to reduce the incidence of canine hip dysplasia and the disabling degenerative joint disease of severe cases? A disease with multiple genes involved in its cause and so many environmental components in its expression is a very difficult problem. That said, other dog breeds have increased the percentage of dogs with normal hip formation when those with poor hips were identified and not bred. Owners of working Border Collies can have hips which receive a normal grade by the Orthopedic Foundation of America (OFA) recorded on the dog's ABCA pedigree by sending the original registration certificate and the OFA certificate (and the processing fee) to the registry office in Perkinston, Mississippi. The ABCA encourages breeders to examine the hip scores in as many relations in the breeding pair's family as possible and it encourages puppy buyers to ask about this information. See the sidebar for preliminary data on what are the chances of getting good or bad hip formation from various mating combinations. Members of the ABCA eye-hip committee are looking at current studies as well as data from the past 20-30 years to develop a breed-specific strategy to help breeders improve their puppies' chances of having normal hip formation. Submitted by the ABCA Eye/Hip Committee Sally Lacy, Chairman Denise Wall, Ph.D., Mellissa DeMille, Ph.D., Amy Coapman, MS The only available predictive OFA figures are those they have extracted from some unspecified dog breeds in their data base. As soon as they can be obtained, data for Border Collies alone will be subjected to a similar analysis. 1. When dogs with Good or Excellent ratings are mated, there is a 12.5% incidence of puppies developing CHD, 87.5% will have normal hips. 2. When a dog with hips rated Good or Excellent is mated to a dog with hips rated Fair, the incidence of CHD puppies rises to 15%, with 85% normal. 3. When a dog which is dysplastic is mated to a dog rated Good or Excellent, the incidence of normal-hipped puppies drops to 75%, and the incidence of CHD jumps to 25%. |
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