a Weimaraner. The same applies for Dobermann Pinschers suffering from Blue dog syndrome. Somatic Mutations and Chimera Somatic mutation, a mutation that can occur in body cells after formation of the embryo, can be passed on to next generations. A pigment somatic mutation can cause patches of different colors (mosaicism) to appear in the dog's coat. Genes associated with hair length, growth and texture Every hair in the dog coat grows from a hair follicle, which has a three phase cycle, as in most other mammals. These phases are: anagen, growth of normal hair; catagen, growth slows, and hair shaft thins; and telogen, hair growth stops, the follicle rests, and the old hair falls off—is shed. At the end of the telogen phase, the follicle begins the cycle again. Most dogs have a double coat, each hair follicle containing 1-2 primary hairs and several secondary hairs. The primary hairs are longer, thicker and stiffer, and called guard hairs or outer coat. Each follicle also holds a variety of silky- to wiry-textured secondary hairs (undercoat) all of which are wavy, and smaller and softer than the primary hair. The ratio of primary to secondary hairs varies at least six-fold, and varies between dogs according to coat type, and on the same dog in accordance with seasonal and other hormonal influences. Puppies are born with a single coat, with more hair follicles per unit area, but each hair follicle contains only a single hair of fine, silky texture. Development of the adult coat begins around 3 months of age, and is completed around 12 months. Research indicates that the majority of variation in coat growth pattern, length and curl can be attributed to mutations in four genes, the R-spondin-2 gene or RSPO2, the fibroblast growth factor-5 gene or FGF5, the keratin-71 gene or KRT71 and the melanocortin 5 receptor gene (MC5R). The wild-type coat in dogs is short, double and straight. L (length) locus The alleles at the L locus (the fibroblast growth factor-5 gene or FGF5) determine the length of the animal's coat. There are two known alleles that occur at the L locus: L = Short coat l = Long coat L is dominant to l. A long coat is demonstrated when a dog has pair of recessive l alleles at this locus. The dominance of L > l is incomplete, and L/l dogs have a small but noticeable increase