Genetics of Coat Color and Type in Dogs
a brief review of the genes controlling dog coat colors and patterns, as well as coat type
Homepage Table of Contents
Please click on the color or pattern of interest to go to the pertinent webpage
COAT COLOR and PATTERN
NOSE COLOR*Updated Jan 2012*
Specific Breed Examples
This webpage was last updated on January 19, 2012 by Sheila Schmutz. firstname.lastname@example.org The linked pages in this series may have been updated more recently however.
Two classic books tell us much about the inheritance of coat colors and patterns in dogs. The one most quoted is by Clarence C. Little, The Inheritance of Coat Color in Dogs, Howell Book House, 1957. The other is by Ojvind Winge, Inheritance in Dogs with Special Reference to the Hunting Breeds, Comstock Publishing, Ithaca, N.Y. 1950. A third book, Comparative Genetics of Coat Colour in Mammals, by A. G. Searle, Logos Press 1968 is also a useful resource. This page is organized by the coat colors or pattern names and the gene loci postulated by Little are included where possible. Molecular studies are showing that Little was usually correct in his hypotheses, but not always.
Many people read a more recent book by Malcolm B. Willis, Genetics of the Dog, Howell Book House, New York. 1989. His terminology is different for several alleles than that of Little. This leads to some real confusion for people who try to read several books or webpages designed by people who have read some of these books. All 3 of these books are out of print so they are difficult to purchase, but try your local library. There is a chapter in a book called The Genetics of the Dog edited by A. Ruvinsky & J. Sampson, CABI Publishing but sold through Oxford in North America, which contains a chapter by Philip Sponenberg and Max Rothschild on coat color. This book is still for sale by order at email@example.com.
None of these books contain DNA studies however. All are based on hypothesized alleles at hypothesized loci to fit data obtained from coat colors and patterns of dogs from various breeds and litters. DNA research has shown that there are more genes involved than those hypothesized by these authors and that the actual number of alleles at genes they discuss is more for some genes and fewer for other genes. An invited review paper on the DNA research on the genes known to be involved in coat color was published December 1, 2007 in Animal Genetics, with the photo page shown above.
There is a very good book entitled "Future Dog, Breeding for Genetic Soundness" by Patricia J. Wilkie. This was commissioned by the Canine Health Foundation. Although the information on coat color does not use the typical abbreviations and is limited in this book, the explanations of basic inheritance and new DNA approaches to research and diagnosis is very good.
This webpage is an attempt to summarize some of the current DNA research being done on dog coat color. Whenever possible, publications are listed documenting the research supporting the statements. Unless otherwise stated, the research that is not referenced is work from our laboratory or work done in conjunction with our collaborators. Sometimes the work is not yet published but is the result of experiments in progress or even just hypotheses of which gene might be the locus Little described from recent DNA findings in other species. It typically takes a year from the time the data are written in a manuscript and that manuscript appears in a scientific journal. We are far from having identified all the genes involved in dog coat color using DNA. There seem to be many more than Little predicted. Therefore do not consider this summary a final conclusion, but merely a work in progress.
When you read these pages and attempt to determine the genotype of your dog or an upcoming litter, please keep in mind that no gene acts in isolation. All dogs have all these genes. In some breeds the alleles are "fixed" which means all dogs are homozygous for the same allele. As a rule of thumb, the more coat colors that occur in your breed, the more genes will be needed to explain the genotype and phenotype of your dog. Furthermore there are interactions among the various genes in the pathway so that some colors are not possible unless particular alleles occur at more than one locus (i.e. a dog must have at least one E at MC1R and two of the b mutations at TYRP1 to be brown).
Our dog color research uses dogs owned by private individuals who participate in our studies by contributing DNA cheek brush samples. Most of the samples come from breeders who respond to a request through their breed club, students in our classes or individuals we approach at dog events. These are not dogs bred in research colonies, but simply dogs living normal dog lives. We thank them and their owners for volunteering their DNA to help us understand the gentics of color better.
Our research has been funded by a number of sources over the past few years. We thank the Canine Health Foundation of the American Kennel Club, the Natural Science and Engineering Research Council of Canada and HealthGene Laboratory, Toronto for their support.
Recently there are several dog clubs, groups and breeders speak about "Color Breeding" with disdain. The research we conduct is not meant to advocate that dog breeders purposefully crossbreed or breed mutants to introduce colors or patterns that were not a tradition in their breed. Our research is meant to help dog breeders understand how coat colors and patterns are inherited so that if more than one color variant has been a classic color in their breed, they can plan matings to get pups of one or another color or several if that suits the aims of their breeding program. I do not think that rare colors should raise the price, let alone the "value" of a dog. I would hope that we value every dog we bring into our life, whatever breed or color it might be.
Color has been an integral trait in the development of many dog breeds. It was used for at least one hundred years as one of the traits under selection. In a few cases, certain colors were selected against because the people at a particular time in history thought these colors typically brought health related problems with them. Some colors do. Other colors were selected against or for because the breeders felt that those colors help that breed do its job better, as in the case of the preponderance of brown colored hunting dogs in the European hunting breeds. Those 19th century hunters thought that brown was a better camouflage color and several of them were poaching game on the baron's land!
"Guessotypes" versus Genotypes
Coat color genetics has fascinated many people for many, many years. There are countless websites posted attributing specific genotypes to specific dogs based on the classic books by C. C. Little (1957) or O. Winge (1950). Many teachers have asked students to attempt such an exercise, as a learning experience, including me.
However, these are at best an educated guesstimate of the underlying true genotype. I sometimes therefore call these “guessotypes” to distinguish them from actual genotypes obtained by DNA testing. Keep in mind, that not all alleles, and not even all genes involved in dog coat color are yet identified and so a complete coat color genotype is not yet possible for many breeds of dogs.
Trying to do good guessotyping requires several high quality photographs, or better, a chance to examine the living dog. Even good guessotyping is prone to flaws when the photos are not great or the dog is a breed that has several possible genotypes associated with the same phenotype, or worse is of a phenotype that changes with age. Trying to guessotype from a word description about the coat color of a dog is especially hazardous.
For example, a dog described as red, black and white could be a black-and-tan dog with white feet and/or face. It could be a fawn dog with a black facial mask and random white spots. It could be a brindle dog with a white chest mark. It could be a fawn dog with a white blaze and black skin showing around its muzzle, but actually no black hair. It could be a merle dog with copper points and Irish spotting. It could be a fawn dog with pale undersides and black tipped hairs along its spine. It could be a fawn puppy with black tipped hairs all over and a small white chest spot that changes to a very pale cream over its entire body by 3 years of age. Words only go so far in accurately describing a coat color phenotype.
Although guessotyping can be fun and even a bit of a useful mind puzzle and/or educational exercise, it should not be used to make serious decisions about the coat colors possible in offspring or parents. In other words, guessotyping has limitations. Therefore let's try to limit its use to certain exercises and not assume that guessotypes are necessarily accurate.
Articles in the Popular Press
Genetics of Coat Color in Dogs. Versatile Hunting Dog, January 2001 issue, p. 13-14. Sheila Schmutz.
Coat Color by Crayon. Canine Review, September 2003 issue. Sheila Schmutz.
Glossary of Terms Used in Relation to Dog Coat Colors and Patterns
Links to Other Coat Color Related Sites
Links to Other Dog Coat Color Related Sites
Links to DNA Testing Services
for further information contact:
Sheila M. Schmutz, Ph.D., Professor
Department of Animal and Poultry Science
College of Agriculture and Bioresources
University of Saskatchewan
Saskatoon, Canada S7N 5A8