Brindle is a coat coloring pattern in animals, particularly dogs, cattle, guinea pigs, cats, and, rarely, horses. It is sometimes described as "tiger-striped", although the brindle pattern is more subtle than that of a tiger's coat. Brindle typically appears as black stripes on a red base. The stripes are eumelanin (black/brown pigment) and the base is phaeomelanin (red/yellow pigment), so the appearance of those pigments can be changed by any of the genes which usually affect them. Eumelanin (the pigment making up the stripes) can be affected by: merle (and harlequin), liver, dilution, greying, and recessive red. Phaeomelanin (the pigment making up the base) can be affected by: Intensity locus. And of course, white markings and ticking can occur on any brindle dog. Brindle is caused by a complex gene process and is technically a form of mosaicism, where some cells express one allele (KB) and other cells express a different allele (ky), a little like tortoiseshell cats. This makes it very difficult to test for, and there are currently no commercially available tests that are able to detect brindle. Brindle dogs will usually test as KBky, and carriers (one dominant black allele, one brindle) cannot be identified without breeding. Dogs The brindle pattern may also take the place of tan in tricolor coats of some dog breeds (such as Basenjis). This coloration looks very similar to tricolor, and can be distinguished only at close range. Dogs of this color are often described as "trindle". It can also occur in combination with merle in the points, or as a brindle merle, in breeds such as the Cardigan Welsh Corgi, although the latter is not acceptable in the show ring. The "dark" markings are black or the dilutions gray (called blue) or brown (sometimes called red). It is not uncommon for a brindled Cairn Terrier to become progressively more black or silver as it ages. Cats Brindled domestic cats are also known as tortoiseshell cats, and in some cases, tabby cats; they are almost exclusively female. Guinea pigs Brindle is an old variety in guinea pigs. They are difficult to breed to perfection, as the black and red hairs should intermingle evenly all over. Brindle guinea pigs' fur type is Abyssinian (rosetted). Horses Brindle coloring in horses is extremely rare and in many cases is linked to spontaneous chimerism, resulting in an animal with two sets of DNA, with the brindle