genetic disease or genetic‐based infertility that a breed‐rescue type of genetic diversity breeding scheme may be indicated.
Genetic tests are extremely useful tools to help manage genetic disorders. Even when there is no test or an unknown mode of inheritance, much can still be done to reduce the incidence of affected and carrier animals (see 3.4 Predicting and Eliminating Disease Traits). The use of these guidelines can assist clients in making objective breeding decisions for genetic disease management while continuing their breeding lines.
It is distressing when a genetic disorder is confirmed in an animal. The veterinary team can make positive and practical genetic counseling recommendations to maintain breed lines and genetic diversity, and improve the overall health of breeds. Each breeder will have their own rate of progress depending on the frequency of the defective gene(s) in their own breeding animals, and which desirable individuals carry liability genes.
With the increasing availability of genetic tests, there is increased risk of misusing and misinterpreting them. There is also the propensity to recommend inappropriate and unnecessary genetic testing, which can diminish client compliance. It is our responsibility to understand the proper use and interpretation of genetic tests, and to provide appropriate genetic counseling recommendations to our clients.
Example 1
A client is interested in acquiring an Alaskan malamute. You or your team discuss the grooming (and shedding) expected in the breed, as well as its exercise requirements. You look up and print out the OFA‐CHIC prebreeding recommendations for the client which includes a hip evaluation for hip dysplasia, ophthalmologist eye examination, and a genetic test for polyneuropathy – a breed‐specific genetic disorder. You counsel the client to ask anyone offering Alaskan malamute puppies for official documentation of the above genetic testing on both parents of the puppies. The OFA‐CHIC also lists recommended testing for hypothyroidism and a cardiac evaluation, indicating that these diseases are also present in the breed. The client should inquire if either of the parents have any health issues, including common genetic disorders such as allergies, cruciate ligament rupture or significant arthritis.
Example 2
You remove bladder stones from a feline patient and submit them for analysis. They come back as calcium oxalate stones. You must counsel the client that this is a genetic predisposition and the cat is at high risk of forming more stones. You offer medical recommendations to minimize the risk of future stone formation. The owner desires to breed the cat. You inform the owner that there is no genetic test for oxalate urolithiasis liability. Due to the severity of the disease, affected cats should not be used for breeding.
Example 3
A French bulldog owner presents their older dog for evaluation due to clinical signs of spinal cord disease. The owner has a commercial genetic test result showing the dog is homozygous “at risk” for the sod1 liability gene for DM. You tell the owner that no French bulldogs have been pathologically confirmed with DM and the genetic test is likely not predictive for their breed. You further inform the owner that French bulldogs have a high incidence of intervertebral disc disease, which is a treatable condition (versus the fatal prognosis of DM). Further work‐up reveals spinal cord compression which is successfully treated surgically.
Genetic disease is observed every day in practice
Genetic counseling involves the treatment of mixed‐breed and purebred patients as well as prebreeding health evaluations.
The veterinary team should be knowledgeable about breed‐specific genetic disorders, especially those that can cause issues with anesthesia, surgery, and drug treatment.
Many breed‐validated disease‐causing genetic mutations occur at significant frequencies in breeds so that selection against them should be done in a systematic “breed and replace” manner so as not to affect the genetic diversity of the breed.
The veterinary team should impress upon clients that purposefully bred dogs and cats should only be obtained from health‐conscious breeders who perform prebreeding health screening and genetic testing.
Abbreviations
OFAOrthopedic Foundation for AnimalsWSAVAWorld Small Animal Veterinary Association
Recommended Reading
1 Ackerman, L. (2011). The Genetic Connection: A Guide to Health Problems in Purebred Dogs, 2e. Lakewood, CO: AAHA Press.
2 Bell, J.S., Cavanaugh, K.E., Tilley, L.P., and Smith, F.W.K. (2012). Veterinary Medical Guide to Dog and Cat Breeds. Jackson, WY: Teton NewMedia.
3.9 Purebreds, Mixed‐Breeds, and Hybrids
Lowell Ackerman, DVM, DACVD, MBA, MPA, CVA, MRCVS
Global Consultant, Author, and Lecturer, MA, USA
3.9.1 Summary
Veterinary teams need to be prepared for a variety of patients these days, with different breed names, descriptions, and predispositions to disease. It has never been more important to ensure that such pets are properly recorded in practice management software, as this can impact risk assessment and appropriate communication with pet owners.
3.9.2 Terms Defined
Hybrid: Also known as a designer breed, this is a cross between two or more purebreds. In most cases, the cross is intentional.
Mixed‐breed: This is the result of a mix of breeds, potentially some known and others unknown. In most cases, the cross was unintentional. There are a variety of other terms for this, such as mutt in dogs and moggy in cats.
Pedigree: Recorded ancestry.
Purebred: An animal of a modern breed with a documented pedigree.
In most veterinary practices, approximately half of all canine patients are mixed‐breeds (and an even higher percentage for feline patients), and there are approximately
