International Efforts to Improve Canine and Feline Genetic Health: The Veterinarian's Role
The important role of the veterinary clinician in the diagnosis, management and control of hereditary disorders and genetic predispositions will be discussed and illustrated with case presentations. The global efforts of improving the genetic health of companion animals will be addressed and easy web resources will be presented. There are many very desirable traits of canine and feline breeds but also many hereditary disorders and genetic predispositions to disease in these species. With the recent completion of the canine and feline genome sequences and molecular techniques, these genetic (breed) traits and defects have been and are being characterized from the clinical signs to the molecular basis. Many specific breed traits such as size, chondrodysplasia, brachycephaly and many skin and coat color characteristics have recently been defined. Moreover, with DNA tests it is now possible to determine the ancestry of mixed-breed and purebred dogs, a first example of a test for a complex trait. Because of the increased awareness of breeders, pet owners and veterinarians of genetic defects and the improved diagnostic abilities in clinical practice, the number of reported hereditary diseases in small animals is rapidly growing. At present, > 900 and > 230 hereditary diseases in dogs and cats, respectively, have been adequately documented.
For the small animal practitioner, it can be a daunting, nearly impossible task to remember all these diseases and be aware of the many novel tests and their appropriate management and control. While breeders and show judges frequently select their champions based mostly on morphological characteristics according to (extremes of) the breed standard, the veterinary clinician should focus on the patient and future health of the companion animals. The veterinary clinician is playing a key role in making the specific diagnosis of an ill patient, recognizing the genetic nature of the disorder and screening related animals to the patient, which may be diseased or carry deleterious traits. As the primary care physician, the veterinarian's role is to also recognize and inform the breeder of the health-related aspects of extreme conformational characteristics such as brachycephalic syndrome, extreme chondrodystrophy, excessive skin and skin folds, excessive hindlimb angulation, excessive size, excessive coat and eyelid abnormalities. Some breeders are taking extreme approaches such as ignoring the genetic basis of the disease or quitting breeding altogether. One leads to the propagation of the disease while the latter may restrict the gene pool of the genetic pool (diversity) of a breed. There are many resources available or being developed for the clinician and international efforts are being proposed to facilitate the genetic heath of companion animals.
Databases on hereditary diseases: It is difficult for a clinician to keep up with the rapidly accumulating information on clinical genetics and the large spectrum of disorders and genetic predispositions. Thus, comprehensive update resources are needed. There are several web sites that provide some information on many different diseases in companion animals such as "Inherited diseases in dogs" (www.vet.cam.ac.uk/idid); "Mendelian inheritance in animals" (http://omia.angis.org.au/home); "Canine inherited disease database" (www.upei.ca/~cidd/intro.htm [VIN editor: Link could not be accessed as of 3-24-2016]); "Listing of inherited disorders in animals" (http://sydney.edu.au/vetscience/lida); and the International Cat Care website list of feline hereditary disorders (www.icatcare.org/advice/cat-breeds). There is also a book on hereditary diseases by breed available by one of the presenters (Bell, Cavanagh, Tilley, Smith. Veterinary Medical Guide to Dog and Cat Breeds. Teton NewMedia; 2012), which lists many hereditary diseases for each breed. Organized efforts to improve canine health are also planned by the recently formed International Partnership for Dogs (IPFD) with its website DogWellNet (www.dogwellnet.com). While clinical and routine laboratory and imaging tests are helpful, specific biochemical and DNA tests have become available for many single gene defects through various laboratories in dogs. As it is difficult to keep track of all the diseases, tests and treatments, a web-based database for available DNA tests on hereditary diseases in companion animals for clinicians is being introduced. The WSAVA Committee on Hereditary Diseases has set up a database on genetic tests for hereditary diseases (http://research.vet.upenn.edu/WSAVA-LabSearch; www.wsava.org; and www.VIN.com) with pertinent practical information on clinical features, genetic diagnostics and management specifically for the clinician.