This webpage is part of a series on the Genetics of Dog Coat Color and Type and mounted on August 26, 2006 by Sheila Schmutz. It was last updated on April 10, 2009.

  • Coat Length
  • Texture

    • Although C. C. Little's book is the considered the classic work on color, he did not address hair length or type. For a discussion of these, one must look Frederick B. Hutt's book "Genetics for Dog Breeders" (1979, W. H. Freeman and Company, San Franciso) Chapter 8 or to the earlier work by by Ojvind Winge, "Inheritance in Dogs with Special Reference to the Hunting Breeds" (1950, Comstock Publishing, Ithaca, N.Y.).

    Coat Length

    Crawford and Loomis (1978) studied 1,216 St. Bernards from 221 litters and showed that short coat (L/-) was dominant to long coat (l/l). They stated that the type of coat is clear by 6 weeks of age. Interstingly they observed that short coated pups had bluish skin and the hair was white at the base, whereas long haired pups had pink skin and that the hair was buff at the base.

    Recently Donna Housley and Patrick Venta published that the gene causing hair length in several breeds of dogs was fibroblast growth factor 5 (FGF5). They studied this gene because it causes "angora" in mice. They initially began their study with Cardigan Welsh Corgi in which the long haired variety is called "fluffy".

    They have shown that the mutation in FGF5 causes hair length differences in Corgi, Collie, Border Collie, German Shepherd Dog, and Dachshund. Shadow, at the left, is a Rough Collie and Prima, at the right, is a Smooth Collie. Since Prima had pups with a rough coat, we know she is L/l in genotype. Different breeds use different names for longhaired and shorthaired.

    At the Third International Conference on Advances in Canine and Feline Genomics held in Davis, CA from August 2-6, 2006, Dr. Housley said they are currently studying other breeds to determine if their hair length differences are also caused by this mutation.

    .
  • Crawford, R.D. and G. Loomis (1978). Inheritance of short coat and long coat in St. Bernard dogs. J. Heredity 69:266-267.
  • D. J. E. Housley and P. J. Venta (2006) The long and the short of it: evidence that FGF5 is a major determinant of canine "hair"-itability. Animal Genetics.

    • Continuously Growing Hair

    Most dogs grow their coat to a specific length and then the hair growth stops. Pups of long coated breeds do not achieve their full length coats for several months.

    In other breeds, the hair keeps growing and growing. Some people refer to these breeds as "non-shedding". Lisa Peterson of AKC was quoted in Pets magazine (Jan/Feb 2006 issue) as listing the following breeds in this category, but there are probably others also.

    Hairless

    A few breeds of dogs do not grow hair and are sometimes called "hairless". The Xoloitzcuintli, often called the Mexican Hairless is a breed that does not grow hair. The Chinese Crested grows hair on its extremities only in one variety, as shown by Melogy on the left. In the other variety, the dog has long hair all of its body and this is called "powder puff".

    The literature states that at least some types of hairlessness are lethal when the dominant allele is homozygous. One copy of the dominant allele would result in a hairless dog. A dog inheriting two copies of the homozygous recessive allele would produce hair.

    The mutation causing the hairless phenotype was discovered using a genome scan by a collaboration of the labs of Kirsten Lindblad-Toh and Tosso Leeb.

    Texture

    Wire

    Wirehaired dogs are coarser textured hair that is more bristley than smooth. Many wirehaired dogs also have "facial furnishings" or a beard. It is quite likely that shorthaired wire coats feel more wirey than longhaired wire coats. The Wirehaired Pointing Griffon is an example of a dog with a wirehaired coat.

    Winge (1950) postulated that wire (W) is dominant to non-wire (w).

    Curly

    Some breeds of dogs have "curly" coats, the Curly Coated Retriever being one example. The Irish Water Spaniel, shown at the right is another example.

    Corded

    Corded coats are probably coats that are both curly and continuously growing. The Puli is an example of a breed with a corded coat, as illustrated by Raz on the right. The Komondor is another breed with a corded coat. It is said that this coat protected sheep herding dogs from being bitten by wolves since it was so thick the teetch didn't penetrate it.

    back to Dog Coat Color Main Page