Coat Color Basics

A Practical Understanding of the Basic Coat Color

Genes B/b and E/e

Without repeating all the wonderful documents available online that delve into coat color genetics to the Nth detail, this is intended as a practical primer for those who need to be able to interpret websites like Vetgen's.

Basic coat color genes:

There are two pairs of genes that determine the basic coat colors in dogs such as Poodles, Labrador Retrievers, Golden Retrievers, and Doodles. These are: B/b and E/e : B is the dominant Black gene. If it is not B, then it is b the recessive brown gene. E is the dominant Extension gene, in conjunction with B/b causes a dog to be black or brown. If it is not E, then it is e the recessive cream gene. There are numerous other genes that can affect coat color, (silvering, phantom, parti, and the like), and those are outside the scope of this document (and beyond the experience of the author).

Definitions:

black - is black coat color and pigment. Black also includes silver and blue. brown - means chocolate, brown, cafe-au-lait and brown pigment. [Sometimes referred to as Liver pigment, but means the same thing. Can vary from pink to dark brown.] cream - means any of the following colors: white, cream, apricot, red, yellow (as in Labs), golden (as in Goldens :) [Cream dogs can have either brown or black pigment.] dominant - A dog need only have one copy of a dominant gene to express that trait. For example, a dog with one B gene will have a black nose. A capital letter indicates a dominant gene. pigment - refers to eye rims and lips as well as noses, paw pads... Used interchangeably with nose, as that's what we usually think of first J recessive - A dog must have two copies of a recessive gene to express the trait. For example, a dog with bb genes will have a brown nose. A single copy of a recessive gene will not affect the appearance of the dog, it is hidden from view. A dog with one or more of these hidden genes is commonly referred to as “carrying recessive <cream / brown>”. A lower case letter indicates a recessive gene.

The (16) possible combinations of B/b and E/e

genes are as follows:

Notice that 9 of the 16 combinations produce Black, 4 produce Cream, and only 3 produce Brown dogs. By convention, the dominant gene is listed first. Since bBeE is the same as BbEe, you won't find bBeE on the Vetgen chart or similar references.

What do all these B/b and E/e combinations mean?

All dogs with an “ee” pair will be Cream: bbee is a cream dog with brown pigment This is the only coat / pigment color combination that can be identified with a single specific set of B/b and E/e genes just by looking at the dog. Bbee and BBee are cream dogs with black pigment: Bbee is a cream dog carrying recessive brown BBee is a cream dog All dogs with a “bb” pair and at least one “E” will be Brown: bbEe and bbEE are brown dogs (with brown pigment): bbEe is brown carrying recessive cream bbEE is a brown dog All dogs with at least one “B” and at least one “E” will be Black: BBEe, BBEE, BbEe, and BbEE are black dogs (with black pigment): BBEe is black carrying recessive cream BBEE is a black dog BbEe is black carrying recessive cream and recessive brown BbEE is black carrying recessive brown

So what good is all this?

The key to putting it all together is that each puppy in a litter gets one of its B/b genes and one of its E/e genes from each parent. Knowing exactly which genes the parent carries allows you to predict the possible coat colors / pigments of the offspring. Sometimes a breeder will do a test litter, and may be able to identify the parent dog's B/b and E/e genes by the offspring they produce. Because of the number of possibilities, this may not be definitive. There is also a wildcard to the test litter approach, mutation of a single gene can sometimes occur, if that gene happens to be one of the coat color genes, then the test litter will include a puppy that is not representative of its parents true B/b and E/e coat color genes. Breeder's have long used the dog's pedigrees as a source for understanding what colors their dog may carry. Sometimes it is pretty straight forward, for instance, a black dog whose parents are a cream and a brown, they know they have a black dog carrying both cream and brown (BbEe). But sometimes it is less straight forward, as in the case where many of the dogs in the pedigree are black, since black hides both cream and brown, so a dog may be BBEE or BbEe or BbEE or BBEe, and it may not be evident from their pedigree. Note that pedigrees are still essential for understanding other coat color genes for which there is no test (silvering, etc.), and of course, for health concerns, temperament, and conformation. So accurate and detailed pedigrees are always essential. If a breeder wishes to know what they are likely to get from a litter before producing any puppies, they can have their dogs B/b and E/e genes tested by companies like Vetgen (a relatively inexpensive, efficient method).

Example 1: Mate two black dogs together and get

all blacks - Maybe not.

Let's assume that Parent 1 and Parent 2 are both BbEe (Black carrying recessive cream and recessive brown). Therefore: Parent 1 can contribute the following genes to its offspring: BE or Be or bE or be Parent 2 can contribute the following genes to its offspring: BE or Be or bE or be Their resultant litter will potentially have the following gene combinations: Note: the lines are numbered for use in Example 4, and for no other reason. Statistically, over time (multiple litters), this breeding pair would produce: 56.25 % Black puppies 18.75 % Brown puppies 18.75 % Cream puppies w/ black pigment 6.25 % Cream puppies w/ brown pigment

Example 2: Mate a brown dog to a cream dog. The

entire litter is black!?!.

For this example, assume that Parent 1 is bbEE (brown) and Parent 2 is BBee (cream with black pigment). Therefore: Parent 1 can contribute the following genes to its offspring: bE Parent 2 can contribute the following genes to its offspring: Be Their resultant litter will potentially have the following gene combinations: 100 % of the puppies are black.

Example 3: Mate a different brown dog to a

different cream dog.

For this example, assume that Parent 1 is bbEe (brown w/ recessive cream) and Parent 2 is bbee (cream with brown pigment). Therefore: Parent 1 can contribute the following genes to its offspring: bE or be Parent 2 can contribute the following genes to its offspring: be Their resultant litter will potentially have the following gene combinations: Statistically, over time (multiple litters), this breeding pair would produce: 50 % Brown puppies w/ recessive cream 50 % Cream puppies w/ brown pigment .

Example 4:

You can use the table in Example 1 to figure out the results of any mating, by simply eliminating the gene combinations that don't apply. Let's assume that Parent 1 is Bbee (cream w/ recessive brown, black pigment), and Parent 2 is BBee (cream with black pigment). Therefore: Parent 1 can contribute the following genes to its offspring: Be or be Parent 2 can contribute the following genes to its offspring: Be Procedure (for using table in Example 1 as a starting point): Cross out the lines for Parent 1 that are not Be or be (cross out lines: 1- 4 and 9 - 12). From the lines remaining, cross out the lines for Parent 2 that are not Be (cross out lines 5, 7, 8 and 13, 15, 16). The lines that are remaining (in this case line 6 and line 14) are the only combinations you should expect from these parents. I.e.: Their resultant litter will potentially have the following gene combinations: Statistically, over time (multiple litters), this breeding pair would produce: 50 % Cream puppies (black pigment) 50 % Cream puppies (black pigment) w/ recessive brown This same procedure can be followed for any B/b and E/e combination of parents because the table in Example 1 has every possible combination. It really is simply a matter of eliminating the combinations that do not apply to your specific breeding pair (Parent 1 and Parent 2).

One Final Comment:

There are far too many combinations (9 for each parent => 81 to be exact), to cover them all here. Hopefully, this explanation, along with the examples, will make it possible for the reader to understand what the Vetgen chart at http://www.vetgen.com/canine-coat-color.html means. Addendum: Thanks to Blue for asking about the B/b and E/e coat color genes thought to be carried by Golden Retrievers. This is my theory, and not to be taken as proven fact! That said, if Golden Retrievers never have brown noses, then they probably don't carry the "b" allele. At least that was my argument for the theory that first cross Goldendoodles won't be chocolate. That being the case, then Golden Retrievers are only be BBee. Seems the only chocolate F1 goldendoodles are ones that come from a breeding with a phantom, so I'm not sure what is going on there, except that another gene pair is probably involved. It would be absolutely fascinating to have one of these chocolate F1 GDs' genes tested by Vetgen to see if they carry the bb gene pair ("normal chocolate"). It might be possible that they don't, and if bred to a normal chocolate, may only produce blacks (except for the offspring that carry the phantom gene - those might come out chocolate). Anyone that can identify a true Golden Retriever with brown pigment, or has an F1 Chocolate Goldendoodle, with verified “bb” genes - please email me! -------------------------------------------------------------------------------- written by Jan, 2004