Jerold S. Bell, DVM
As veterinary medical professionals, we are at the front lines of improving the genetic health of our patients, of breeds, and of all dogs. For most genetic diseases, we know how to either prevent their occurrence, or at least lessen the possibility of producing offspring with genetic disease. This can occur through the genotypic testing of the parents (identification of parents carrying liability genes for genetic disease), phenotypic testing of the parents (identification of parents affected with genetic disease), or pedigree analysis (identification of carrier risk based on the knowledge of carrier or affected relatives). (See the proceedings for the lecture "Genetic Testing and Genetic Counseling in Pet and Breeding Animals.")
The genetic improvement of dogs will only occur through selective breeding. However, the responsibility for this improvement lies not just with the breeder; but also with the veterinarian, the breed organizations, and the general public. We all have our roles in the genetic improvement of dogs, but improvement will not occur unless we all understand our roles and responsibilities. Inherent in these responsibilities is the acknowledgement that breeding without genetic testing is irresponsible, and unethical. Genetic testing is health quality control. It is no longer acceptable for a breeder to choose two dogs and breed them together without regard to genetic disease control.
There is an active debate and inquiry into the genetic health of dog breeds. Several reports offer similar recommendations of avoidance of selection for extreme phenotypes, the use of genetic testing to select for healthy breeding animals, and modification of breeding practices. The Kennel Club in the UK has initiated a program entitled, "Fit For Function, Fit For Life". At the heart of the program is the belief that all dogs should be able to see, walk, and breathe freely. One extreme phenotype that the Kennel Club is addressing is the brachycephalic syndrome, which can cause life threatening dyspnea and syncope. The Kennel Club (which in the UK owns the breed standards as opposed to the AKC in the US), has amended the standard of the Pekinese to "be required to have a defined muzzle." This is the first of many changes in breed standards that the Kennel Club is undertaking to address extreme phenotypes. The Kennel Club also has an Accredited Breeder Scheme to identify breeders that do health testing and adhere to specific breeding standards.
In the United States, several genetic registries have been established to assist breeders with genetic disease control. The Canine Eye Registry Foundation or CERF (http://www.vmdb.org/cerf.html) is a closed database showing only normal eye examination results by ACVO boarded veterinarians. The Orthopedic Foundation for Animals (OFA: www.offa.org) has semi-open registries for hip dysplasia, elbow dysplasia, autoimmune thyroiditis, congenital cardiac disease, and patella luxation. From the OFA web portal you can look up individual dogs, and their health testing status. This is Facebook for dogs; each with their own web pages and information.
The Canine Health Information Center or CHIC (www.caninehealthinfo.org) is an open health database that has been established by the AKC Canine Health Foundation and the Orthopedic Foundation for Animals. National parent clubs decide to enroll in the CHIC program, and determine the testable genetic disorders for their breed. (For example, hip evaluation, CERF examination, and thyroid testing.) Owners, breeders, and prospective owners can search online for dogs in the OFA/CHIC database, and view their test results. If a dog completes the recommended testing panel, it receives a CHIC number regardless of whether it passes all of the tests. CHIC is about health consciousness, not health perfection. As more testable disorders are identified, few dogs will be normal for all tests. The Kennel Club in the UK has similar Health Breeding Schemes and a searchable Health Tests Results Finder to look up individual dogs.
Responsibilities of Veterinarians
With each hereditary issue, we as a veterinary profession are being called upon to determine what is "normal", what is "abnormal", and what screening tests can be performed to allow selection away from disease causing phenotypes. Care must be taken, so that selective pressures are not so severe that they limit genetic diversity in the breed gene pool.
When a client makes an initial puppy appointment, we should examine all of the paperwork provided by the breeder or pet store. This includes not only the prior medical care, but the registration paperwork that lists the sire and dam. On receiving the paperwork, the health test requirements for the breed can be identified, and the health test results of the parents searched. If test results are not available on the web-based registries, ask the owner if the breeder provided them with verification of each of the required genetic test results on the parents; i.e., a copy of the official test results from the testing agencies. If no verified test results are available, then the puppy was not bred by a health conscious breeder. There is no expectation of genetic health in your patient, and you and the owner can only hope for good health.
When a client is planning on breeding a dog, you can look up the pre-breeding health test requirements. You can provide many of the tests yourself (radiographs, thyroid profile, or cheek swab or blood samples for genetic tests). For eye examinations or heart examinations by a cardiologist, you can assist your client by providing information on local health screening clinics. You must emphasize the ethical responsibility of pre-breeding genetic testing, or a decision to not breed their animal. Genetic testing is a requirement, not a choice.
If a client is looking to purchase a purebred or designer-bred dog, you should counsel them on the behavioral and genetic expectations for the selected breeds. Provide them with the genetic health test requirements. Ensure they understand that they should only purchase a pet from parents that have verified results of their breed-specific required health tests.
Responsibilities of Breeders
It is the ethical responsibility and obligation of all breeders to perform the available required pre-breeding genetic health tests on prospective breeding stock. A breeder is anyone that plans a mating between two dogs. These include matings between two members of the same breed, or crosses between two members of different breeds (designer matings). The most common genetic diseases of canine hip dysplasia, valvular heart disease, patella luxation, and hypothyroidism occur at similar frequencies in mixed-breed versus pure-bred populations. If two animals are purposely bred, then the breed-specific genetic testing for each parent is required.
Most genetic tests only need to be done once in the prospective breeding animal's lifetime. Others (eye examinations, phenotypic heart examinations, thyroid profile, etc.) should be repeated, depending on the breed specific age of onset of the disorder, and age requirement for diagnosis.
If a breeder is not willing or able to have the prescribed pre-breeding genetic tests performed, then they should find a different hobby or profession. Dogs are living beings. It is not ethical to forgo the obligation of genetic testing.
Everyone loves their breed, and their own breeding stock. The more genetic tests that are developed, the greater chance there is of identifying an undesirable gene in an animal. Conscientious breeders understand that negative test results limit their breeding options. With direct gene tests, they can use carriers when bred to normal testing mates. For disorders without direct gene tests, they may have to choose a normal relative, as opposed to one they were planning on using in the next generation. Matings should be planned that prevent or minimize the risk of producing genetic disease.
When prospective breeding stock has a carrier or affected test result, you should counsel your client to release this information to the listing health registry. If negative test results are not made available, then other breeders will not be able to ascertain the disease risk of their own breeding stock to make informed breeding decisions. As opposed to the stigma that used to be attached to the appearance of genetic disease, the stigma now rests on those that hide the occurrence of genetic disease. Dealing with genetic disorders is a community effort.
When making breeding decisions, breeders can search the health registry websites for genetic test results on prospective mates. If test results are not available on dogs that have already been bred, then it must be assumed that they are affected or carriers. Otherwise the results would be available.
When selling a puppy, breeders should provide new owners with full documentation of the health test results (copies of official test results) on the parents. If early direct genetic testing was done on the puppies, these results should be provided. It is not enough to say that the testing was done. If testing was done then the breeder has the paperwork, and it should be provided. It must be impressed upon the public that health consciousness is one of the most important considerations when getting a puppy. Health guarantees that provide for replacement of puppies with genetic defects are not a replacement for health testing. Such a guarantee is of little value, as no one wants to part with their family member once the emotional bonds have been made. A puppy is not a toaster.
Responsibilities of Breed Organizations/Parent Clubs
It is the responsibility of the breed club to conduct regular breed health surveys to monitor the health of the breed. If breed-related disease is present, it is up to the breed club to promote and fund research to identify phenotypic and genotypic tests that can be used by breeders to improve the genetic health of the breed.
For dog breeds, the parent club should work with CHIC, the Kennel Club, or other national agencies to select the required and recommended genetic testing that should be performed before dogs are bred. Breeders should be counseled to perform pre-breeding health testing.
Parent clubs should review their breed standards and select against morphological changes that promote disease, morbidity, or mortality. They should counsel their breeders against breeding to extreme standards that can promote disease, and should educate judges to select against morphology that promotes disease.
The parent club should also scientifically monitor if significant health issues are being caused by a lack of genetic diversity. If so, they should be open to scientific measures that can increase genetic diversity, including opening of the stud book, or even controlled crossbreeding programs.
Responsibilities of the General Public
When a consumer gets a puppy, the emotional aspect of adding a new member to the family often overwhelms the rational aspect of this important decision. Acquiring a new pet should not be an impulse decision. The new pet will hopefully be with the family for the next 10 to 15 years. The public should spend as much time researching this decision as they do when purchasing a new car or a refrigerator.
Prospective owners need to research whether a specific breed is suitable for them and their home. They also need to research the breed-specific health testing requirements for the selected breed. Whether purchasing from a private breeder, one found on the internet, or a pet store, the parental health testing results for both parents should be available. If they are not available, then just walk away--regardless of how cute the puppy.
Statements of testing by the breeder, or on a breeder website are not sufficient to document health test status. If the testing has been done, the breeder will be happy to provide the official documentation that they are a health conscious breeder. Health guarantees that provide replacement for pets with genetic disease do not eliminate the need for genetic testing. If a breeder states that they do not have the health test documentation, but offer a guarantee of genetic health, the prospective owner should walk away. The breeder has not fulfilled their ethical responsibility and obligation of health testing.
The general public is the engine that drives the pet breeding industry. If the general public demands puppies from health tested breeding stock, then the market will change to favor health conscious breeders. If people can easily sell pets to the public on a website without any health tests being done, then there is no market force to change the situation to improve the genetic health of dogs. It is the public's choice of where they get a puppy. It is the general public's obligation to document genetic health testing from breeders.
All genetic diseases are not preventable. However, the frequency of genetic diseases can be significantly decreased, if not eliminated by valid testing and breeding selection in purposely bred dogs. It is time to put an end to the excuse of ignorance of the breeder, veterinarian, or general public in their roles and responsibilities to improve the genetic health of dogs. It is up to all of us to educate each other about producing genetically healthy dogs, and call for the documentation of health testing of all breeding stock.