Over 200 genetic mutations (variations, deletions, and in-
sertions) have now been associated with development of a 
clinical disease in dogs and cats and an additional 100 or so 
companion animal diseases have been identified without a 
mutation yet identified. As veterinarians have become better 
at understanding and preventing nutritional and infectious 
diseases, disease prevalence has decreased; however, we are 
faced with several familial disease, particularly, but not limit-
ed to, the purebred dog or cat. 

Several diagnostic laboratories now offer genetic tests for sev-
eral canine and feline diseases. Samples may be submitted in 
a variety of forms including buccal swabs, blood samples in 
EDTA and semen straws, and samples can be submitted with 
or without the involvement of a veterinarian. However, the 
role of a veterinarian is critical in interpretation of genetic re-
sults. Although submission and running of genetic tests is not 
complicated, interpretation of the results and how it may im-
pact an individual animal or a breeding program can be quite 
complicated and requires the medical knowledge of a veter-
inarian to help an owner understand the many complicated 
aspects of genetics, including variations in penetrance and 
expression. Without careful counseling and discussion with a 
trained veterinary professional, a pet owner or breeder could 
lose enthusiasm and trust in genetic testing and we could lose 
this important tool. 

Once genetic testing becomes available for a disease, counsel-
ing a pet owner or breeder on how to apply test results is very 
important. A breed association may be quick to immediately 
remove animals with a mutation from the breeding pool. Al-
though this approach may appear as a good idea, it can have 
substantial negative impact on the breed. If the mutant gene 
exists in 40% of a cat or dog population, a sudden reduction 

Role of genetic testing for diseases of 
companion animals and genetic counseling 
in modern veterinary medicine

Kathryn Meurs
Department of Clinical Sciences, College of Veterinary Medicine
North Carolina State University Raleigh, NC

Abstract

Several hundred genetic mutations have now been associated with development of clinical diseases in dogs and cats. Many diag-
nostic testing laboratories now offer genetic tests and samples may be easily submitted. However, interpretation of the results and 
how it may impact an individual animal or a breeding program can be quite complicated. Regardless, with their veterinary medical 
knowledge, the  veterinarian has a critical role in interpreting genetic results.

Keywords: Genetics, mutation, inherited, breeding

in 40% of the gene pool could dramatically alter the breed. 
Additionally, due to complicated genetic phenomenons noted 
in many genetic diseases, not all animals that have the muta-
tion will develop a clinical form of the disease. These concepts 
need to be carefully weighed against the issues of continu-
ing to produce animals that may carry a mutation and could 
potentially suffer from the disease. For the breeding animal, 
recommendations to continue breeding should be based on 
many factors including size of the breed association, type of 
disease, risk that the animals produced will develop disease 
from the mutation, and severity of the disease. Positive attri-
butes of the animal should be considered. 

Besides the development of healthier animals through breed-
ing practices, genetics are a key way for veterinarians to be-
come more proactively involved in patient care. Ability to 
develop a proactive management plan for animals that test 
positive for a disease mutation is the true benefit of clinical 
genetics. Although identification of mutations can be used 
for testing and developing a breeding program, it is unlikely 
that we can ever completely remove many of these variants 
from the population. Larger gains will be in the value of test-
ing young animals for these mutations and developing clini-
cal management plans that can be applied for the lifespan of 
that pet to provide the best possible care. Veterinary medicine 
needs to move away from being ‘reactive-responding’ once a 
disease has been diagnosed, to become as proactive as possi-
ble, identify animals at risk of a disease, and implement man-
agement plans to prevent or alter outcomes. 


	Role