The Sheltie (Shetland Sheepdogs) is a breed of small herding dogs. The sheltie breed originated in the Shetland Islands. Originally, Shelties were bred by crofters as to keep sheep out of their vegetable gardens and to warn of intruders. The coat colors and markings of Shetland sheepdogs (sheltie) and Collies are similar.
The basic scheme for Sheltie loci, genes, and alleles was established by Little in 1957 for coat color genes in dogs in general. Here, we largely follow this scheme, listing only the alleles (flavors of the genes) thought to exist in Shelties.
Three genes are probably the most important for controlling coat color in Shelties:Agouti gene:
This is the principal coat color gene in the sheltie, producing sable or black coats. Either two or three alleles of this gene are present in shelties.ay - sable coat color
In the absence of merling: ay-ay pure for sable shelties usually have golden sable coat. ay-at and ay-ab shelties usualy have sable coats with some extent of black and are referred to as shaded sables (and also, confusingly, as trifactored sables). at-at and at-ab shelties are Tricolored. ab-ab shelties are Bicolored.
The phenotypes of pure for sable, trifactored sable, and bifactored sable Shelties can be very difficult to distinguish. There are pure for sable shelties with a shaded sable phenotype, and trifactored sable shelties with a golden sable phenotype. Bifactored and trifactored sable Shelties also produce an indistinguishable range of phenotypes. In general, a sable sheltie with trifactors or bifactors tends to have substantial amounts of dark hair in the coat, while a pure for sable Sheltie tends to have a pure golden sable coat.