American Kennel Club & AKC Canine Health Foundation National Parent Club Canine Health Conference Proceedings

Abstract

Selective breeding to exploit physical attributes and certain behavioral skills has made the modern dog one of the most physically diverse species on earth. One unfortunate consequence of the inbreeding necessary to obtain dogs with the desired traits is the propagation of genetic diseases within many breeds. Many of these diseases, such as cancer or autoimmune disease, can occur late in life after dogs carrying a disease have been bred. Thus, even the diligent and responsible breeders may unknowingly propagate undesirable traits within their breed. Autosomal recessive traits present the greatest problems, as carriers are often bred several times before the passage of mutant alleles to offspring is obvious. Additional complications are caused by multigenic traits, or by disease caused by genes for which there is variable penetrance. We are interested in identifying genes which contribute to disease susceptibility in dogs. Towards that end, we are creating a genetic map of the canine genome. When analyzed together with the disease status of members of a family, genetic markers highlight regions of the genome likely to contain genes of interest. Carrier dogs are thus able to be identified in the absence of test breedings. The ideal map will be composed of a large number of ordered and highly polymorphic markers, anchored to known genes. To simplify their development as diagnostic tools, each marker should be easily and cheaply assayable and encode a large number of alleles within multiple breeds. Since many canine diseases are appropriate models of corresponding human conditions, the study of canine disease genes is certain to generate knowledge regarding human disease as well. In this presentation we will describe the development and characterization of genetic markers as a resource of map building. The current state of the map will be summarized and examples of its use will be discussed. We will also consider the types of canine pedigrees most suitable for genetic linkage analysis. Finally, we discuss the issue of genetic markers as diagnostic tools in anticipation of breeder related issues such as genetic registries, restricted breeding, and long-term health care of pets.