Interesting article-Unleashing the Canine Genome
"Over 360 genetic disorders in dogs have been described to date (Patterson 1980, 2000). This constitutes the largest set of naturally occurring genetic disorders in any nonhuman species (Patterson 2000)."
"For Golden Retrievers, the considerations are somewhat different. This extremely popular breed was developed in 1868 by Sir Dudley Majoribanks of Guisachan, Scotland, who is reported to have initiated the breed by crossing a Tweed Water Spaniel (a now extinct breed) to a yellow retriever that likely carried the gene pool of several distinct types of retrievers from Labrador and Newfoundland (Rogers Clark and Brace 1995; Wilcox and Walkowicz 1995). The resulting progeny were bred for performance, and outcrosses were done with Labradors, Red Setters, Bloodhounds, and probably others, to allow for opportunities for selected variation in coat consistency (flat, wavy, and curly) and color (cream, golden, yellow to reddish gold). The breed was imported to the United States in the early 1900s and was officially recognized by the American Kennel Club in 1932. Because of its striking appearance, friendly temperament, and intense desire to please, the breed is consistently ranked as one of the most popular.
Unlike the Rottweiler, Golden Retrievers have not experienced any recent major bottlenecks. However, as this is a dog that tends to do well in dog shows, it exhibits several examples of strong popular-sire effects. The estimated relative risk (2.1) of all malignancies for Golden Retrievers was significantly greater than the comparable rate for all other dogs combined (Priester and McKay 1980), and lines of Golden Retrievers with an unusally high incidence of cancer have been reported anecdotally. Because of the popular sire effect, LD is expected to be present over large distances within groups of Goldens related through a single sire. As a result, we predict that examination of haplotype sharing among affected dogs from a single line will easily identify the region containing the disease mutation. Screening of as few as 10 affected individuals has excellent power to detect regions of identity by descent under conditions of genetic homogeneity (which is expected within a single line), while screening 40 affecteds has high power to detect such sharing even under conditions of moderate heterogeneity (Houwen et al. 1994; Puffenberger et al. 1994). We hypothesize that different lines of dogs will share the same mutation because of an even older shared ancestor. In this case, the overlap of regions of haplotype sharing observed among the different lines of dogs would allow us to dramatically narrow the location of the disease gene."