laboratories, institutes, veterinary organizations, and commercial genetic testing enterprises. The research is frequently undertaken in collaboration with veterinary professionals and owners, often relying upon information contained within health registries. An emerging model in some countries as well as in large veterinary companies with multiple hospitals is the wholesale collation of health records from individual veterinary practices for the purpose of facilitating research. Financial support for research into companion animal medical conditions comes in the form of grants from private foundations including the Canine Health Foundation, Morris Animal Foundation, Winn Feline Foundation, Grayson‐Jockey Club Research Foundation, and the Sport Horse Research Foundation as well as federal granting agencies when the work directly supports human health. Additionally, veterinary specialty board organizations may direct funds for the research of targeted health conditions, such as the American College of Veterinary Ophthalmologists and vision loss. Private foundations rely upon philanthropic donations to support their grant funding activities whereas commercial enterprises generally reinvest a portion of the resources obtained from marketing and sales of DNA testing.
The objective of the research is to develop predictive tools for owners and veterinarians to better manage health conditions in companion animals. Outcomes of research are phenotypic tests such as orthopedic, cardiac, ocular, and metabolic screenings that can be deployed generally once validated by healthcare professionals. Genetic mutation tests are the ultimate goal of the research as they are most predictive in disease expression or the propensity of an individual to pass genetic risk on to the next generation (see 3.6 Genetic Testing). In the absence of the mutation test, linked tests may provide guidance although caution must be applied due to the lack of accuracy of such linked tests.
Health screening diagnostics developed through research must be properly validated across many unrelated individuals living in varied locations and exposed to different environments to assess general applicability of the test. Prior to incorporating testing is an understanding of limitations that might exist for a given test in order to manage those limitations and expectations. Genetic mutation tests are usually 100% accurate; however, accuracy relies upon the generalizability of the test across breeds, the testing procedure, and the quality of the genetic testing laboratory. Ideally, researchers subject their findings to the peer review process prior to making a proposed test available.
3.7.6 Utility
Health registries provide the information background for researchers seeking to establish the genetic underpinnings of disease. With widespread owner participation, researchers can identify families or breeds having a high prevalence of a particular disease and then characterize inheritance and collect appropriate DNA samples for genetic studies.
Health testing is important for all companion animals because mixed‐breed and purebred pets all have the possibility for disease. Knowledge that there is a predisposition for disease will permit the owner and veterinarian to best care for the pet long term (see 1.2 Providing a Lifetime of Care). Some diseases may be treatable or have limited impact on a dog's quality of life whereas others may require aggressive intervention. Broad‐scale testing and submission of those test results to a health registry provides the needed data to permit confidence in predicting health risks.
Samson is a well‐bred, accomplished German shepherd dog whose owner was approached by a friend who wanted to breed his very nice female German shepherd dog to Samson. Although Samson had quality hip conformation, Samson's uncle had poor hip conformation, so Samson's owner studied the OFA health registry for the health clearances of the female. The potential dam, and all her relatives, had good‐quality hip conformation. Samson's owner agreed to the breeding because the risk of hip dysplasia in the offspring was very low and in fact, the puppies all had good hip conformation at adulthood.
The owner of Benji, a Bengal cat, read about progressive retinal atrophy in the breed, an autosomal recessive disease that causes blindness. Both carriers and homozygous normal cats will have normal vision; only if the Bengal is homozygous for the progressive retinal atrophy‐b mutation will it be blind. The genetic mutation test revealed that Benji was a carrier. Benji's owner was relieved that the cat would not go blind. Furthermore, the test results were submitted to the genetic health registry and future and current Bengal cat owners could use that information in their own decisions.
Health registries serve multiple roles, all of which are designed to protect and promote the health of companion animals.
Genetic health registries compile health data provided by owners or veterinarians and have the greatest utility with broad participation.
Veterinarians should encourage current and future owners of all companion animals to do health screenings and submit all relevant results to health registries.
Veterinarians and owners should explore the information in health registries and use that knowledge in selecting pets to promote overall pet health.
Health registries form the backbone of research, which enables the development of genetic tests to reduce disease.
3.7.7 Cautions
A great many of the genetic tests available have not yet been fully validated or do not apply to a given breed. With the proliferation of genetic testing companies that screen for hundreds of mutations simultaneously and the aggressive marketing directly to owners, veterinarians must counsel against the tendency to misapply or overextend results from genetic tests. Whereas many current genetic tests may be recorded in a health registry, many may have no relevance to the individual animal because the test may only be valid in a different breed. Thus, there is a growing need for understanding and interpreting test results and applying those judiciously to the pet as a whole.
Abbreviation
OFAOrthopedic Foundation for Animals
Recommended Reading
1 Bell, J.S. (2011). Researcher responsibilities and genetic counseling for pure‐bred dog populations. Veterinary Journal 189 (2): 234–235.
2 Farrell, L.L., Shoenebeck, J.J., Wiener, P. et al. (2015). The challenges of pedigree dog health: approaches to combating inherited disease. Canine Genetics and Epidemiology 2 (3).
3 Moses, L., Niemi, S., and Karlsson, E. (2018). Pet genomics medicine runs wild. Nature 559 (7715): 470–472.
4 O'Neill, D.G., Church, D.B., McGreevy, P.D. et al. (2014). Approaches to canine health surveillance. Canine Genetics and Epidemiology 1 (1): 2.
3.8 Genetic Counseling
Jerold S. Bell, DVM
Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA, USA
