Coat Color Genetics in Lhasa Apsos

by Catherine Marley

There are at least nine distinct coat color gene loci in Lhasas. The interactions of these nine genes result in the wide variety of colors seen in the breed. A "gene locus" refers to a site on a chromosome where the gene for a particular trait is located. Any one of a number of variations of that gene may be found at that site. These variations of the gene are called "alleles". Every Lhasa has two alleles from each of these nine series of genes; one allele of each series from the dam, and one from the sire. Even though a locus may have four or more different possible alleles associated with it, a single animal has only two chromosomes which carry that particular gene locus, and therefore can have, in its private genetic collection, only two genes of each allelic series.

Before discussing the various color loci and their alleles, we should first define the basic genetic types of coat color.

1. SOLID BLACK These animals have no red, gold, or cream hair. They may, however, carry white markings. Any dog who appears black, but has any golden hairs on him, especially on the face, feet, or under the tail, is not a genetic black, but a black and tan.

2. CLEAR TAN (red, gold, cream, or white): These dogs have no dark pigment (black or liver) in their hair coats, even at birth. Some sables lose their black hairs at maturity. These should not be confused with the true "clears", who have no dark markings at birth.

3. BLACK AND TAN This pattern is easily confused with solid black, due to the frequent presence of white sox and other white markings, which can conceal the tan. Very light cream markings may also be mistaken for white. The best place to took for the B&T pattern is under the tail. White markings rarely occur there, but B&T markings invariably do.

4. SABLE (red, gold, cream or grey): This is the commonest Lhasa coat color. It is composed of a mixture of light and dark hair in varying proportions. The color of the light hair can vary from red to light cream or white. The dark hair is usually black, but can be liver or grey, depending on the genetic modifiers present. Any red, gold or cream dog, born with any degree of dark tippings or overlay, is a genetic sable.

5. BRINDLE (red, gold cream): This color is seen in dogs coming down from English pedigrees.  The pups are born with distinct irregular stripes of black on a lighter background, but the pattern becomes indistinct in the adult.  Brindles invariably turn grey with maturity.

The DARK pigment  of these basic coat colors can be modified by several other genes:

The particolor gene can change any of these four basic coat colors to the particolor equivalent, by adding white areas to the basic color.

The greying factor can turn the dark hair of any of these colors grey with increasing age. The noses remain black in the case of the greying factor.

The blue gene will also cause greying of the dark hair but it will be detectable in the young puppy. The nose of a blue puppy is usually grey, and the eyes are grey or hazel.

The liver gene can change the black parts of all four coat patterns, including the noses, to liver or brown. The eyes also are usually a lighter brown or yellow.

The LIGHT pigment  of these basic coat colors can be modified by another gene:

The red/gold dilution factor controls the depth of red/gold pigment from deep red to pale cream/white Now we can consider the actual genes. (Remember that a series may contain four genes, but each animal can have only two genes from each series.)

I. The K series controls the distribution of the DARK coat pigment.

K:­ The "K" gene is the most dominant in this series. It causes dark pigment to be distributed in a "solid" pattern. If one "K" gene is present, the dog's black pigment, if he has any, will cover the body in a solid pattern. i.e. solid black.

K^br: This is the Brindle factor.  It is recessive to K but dominant to the third allele in the series, "k"

k:  This gene causes the dark hairs in the coat to be neither solid coverage (black) nor clumped as brindle, but to be distributed in another of two patterns under the control of another  locus - the "A" locus.

II.  The A series controls the patterning of the dark areas of the coat.

A^w:  This pattern of black pigment in the hair is seen in wolves and some northern breeds, and consists of dark and light bands on the individual hairs.

a^y:  The a^y gene is recessive to "A^w", but dominant to the next gene in the series. a^y causes the dark pigment to be distributed in the "sable" pattern. a^y can be "covered up" if the dog's other gene (of this series) is "A^w". In this case the "wild" pattern would dominate. (The distinction between "sable" and "wild" is questionable however, since I find very little to distinguish the two.) The dog will be sable if its other A ­series gene is a^y or a^t .  The  dominant black gene "K" will obscure  the a^y pattern of a sable dog if it is present, since sable depends on k.

a^t:­ This is the most recessive allele in the A series. It produces the black and tan pattern. It can be covered up by both A^wand a^y . A^w,a^y and A^w,a^t will both be "wild" wolf colored. a^y,a^t will be sable. Only a^t,a^twill be black and tan. Thus black and tan can be carried as a recessive by both solid true blacks and by sables. Black and tan pups may result from mating a sable to a sable, but a true black never comes from a sable x sable mating unless it is the rare recessive a black. True black can result from a sable x clear mating, if one of the ancestors of the clear parent was a true"K" black. (or true black parti.)  If the brindle gene is present it will cause the brindle pattern to appear in the tan areas of the coat.  The other possibility producing a black from sable parents is if both parents carry the recessice black "a" gene.

a: This gene is the recessive form of black. It causes an inability of the animal to manufacture the tan form of melanin "phaeomelanin"- it can only make the black "eumelanin", so the animal will be solid black over all the pigmented parts of the body.

III. The B series has only two alleles affecting the COLOR of the DARK pigment.

B - is the allele for black pigment in coat and nose, and is dominant to b.

b - is the allele for liver or brown, recessive to B. Again, B will cover up b. A liver puppy will only result if there are two b genes, one from each parent. In the case of such a liver puppy, each parent had to be either Bb or bb.

IV. The C series has three alleles. C acts on the LIGHT areas of the coat to cause the variation from red to cream or white.

C is dominant and produces full red or deep gold pigment in the light areas of the coat (if there are any).

c^ch is the next in order of dominance, and causes dilution of the red or gold to cream. Of course this gene would be invisible on the solid black animal, because it has no light areas where the gene can act.  c^ch has less effect on the dark hair than on the light hair.  Any grey sable, or "silver" is simply a red sable whose red hair has been bleached out by the action of c^ch .

c^e is the most recessive and causes extreme dilution of red. In a single dose, in combination with C, it can cause some dilution, even though C is dominant. In fact, the whole "C" series exhibits incomplete dominance, so that a Cc^ch will be slightly lighter than a CC, and a Cc^e will resemble a c^chc^ch. In double dose (c^ec^e), there will be a condition of near­albino color, with reduction of dark pigment as well as light. Nose and eye pigment is diluted, and any black on the coat will be reduced to pale grey.

V. D is the gene for dilution of DARK pigment. (Just as C controlled the light pigment)

D is dominant and gives deep concentrated dark pigment on the hair, nose and iris of the eye.

d is recessive and causes the so called "blue"dilution, as seen in the blue Great Dane. I have seen several Lhasas with this color. The blue dilution is evident in the very young puppy and is characterized by a slate color of the black areas of the coat, a slate grey nose and grey or hazel eyes. The Weimarener is an example of dd acting on liver pigment to produce that peculiar silver­blue liver color.

VI.  E controls the production of DARK (black or liver) pigment. (This pigment will be distributed according to the directions of the pattern gene, A.) The decision of whether or not to make ANY dark pigment, on which A can act, belongs to the E series.

E^m In is the most dominant, and produces dark pigment anywhere the A series tells it to. In addition, it produces a black (dark) mask. The mask will be invisible in the solid black pattern, but will be evident in the sable and black and tan patterns.

E also causes production of dark pigment, under the direction of the  K and A series, but without the mask. It is recessive to E^m, but dominant to e.

e is recessive to both E^m,  and E and prevents production of any dark pigment anywhere in the hair coat. Even if the K and A genes for solid dark pigment is present, the animal will have no dark hair. This is because no dark pigment is produced, on which the pattern genes, K and A, can act. Every dog who is ee in genotype will be a clear shade of red, gold, cream or white regardless of the other genes he may have. Only the particolor gene can express itself in the ee dog, (pale gold and white). Because all the dark pattern dominants are hidden in the ee gold, the solid pattern KA will not be seen. When such an ee KA cream is mated to an a^ya^y EE sable, the K's, A's and the E's get together, producing a true solid black litter (K?, Aa^y ,Ee^ch). This is the only instance where a true black can be born of a gold x gold mating.

VII. G is the greying factor. This is the gene which turns the Yorkshire and Kerry Blue Terriers' black puppy coats to the mature blue­grey shade. In contrast to the D gene, these pups have black markings and black noses. The change to grey is progressive with maturation, but the noses stay black. G is dominant, and causes greying. This gene seems to be common in Lhasas, changing black puppies to smoke at two years, and red sables to "mud" color.

g is recessive and causes little or no greying with maturity. 

VIII. S is the factor controlling white spotting. Like the C series, the dominance of the S series is incomplete. S is the most dominant and produces solid coats, Most Lhasas have some degree of white spotting, so we can assume that the S gene is fairly rare in the breed. In breeds such as Irish Setters and Labradors, there has been heavy selection for the S gene, because of the disqualification of white markings.

sⁱ produces a small amount of white, and is recessive to S.

s^p causes the typical particolor pattern of white markings

s^w is the most recessive gene in this series, and produces extreme white spotting: an all white dog with dark markings on the head.

 As previously mentioned, the dominance of S is not complete. s^p combined with S will produce markings indistinguishable from sⁱ: a little white ring around the neck, a white head spot and tail tip, and white feet. These markings may reveal the presence of a recessive particolor gene in a presumably solid colored dog. s^w, in combination with S or sⁱ, can result in atypical particolor patterns.  The s^w gene is associated with cochlear deafness.

IX. The last gene series is T, the ticking factor. Ticking occurs on white areas which are produced by "S" series genes. Ticking does not occur on white which results from the other white (really cream) producing gene, c^e. Paws which were pure white at birth, at three months will be partly filled in, and at maturity may be a roan due to the ticking gene. This gene is rarely if ever seen in Lhasa Apsos.

T is dominant, and causes ticking.

t is recessive ­ no ticking.

  GENE SUMMARY

ANALYZING COLOR GENES IN YOUR DOGS

Even only one litter can tell you a lot about the coat color genetics of your dogs. This can be very helpful when it comes to breeding that particular dog or bitch again. At least it will save you the embarassment of accepting reservations on four gold puppies, then having a litter of whites and blacks!

I bred a gold sable bitch to a red sable male. Of seven pups, three were black and tan, three were sable, and one was clear cream gold. From this litter I know the following:

1. Both parents are sables, so they must both have a kk, an a^y and an E.

2. Since I got a^ta^t and ee pups, both parents must also carry a^t and e.

3. There were no blues or dilute creams, so the parents each carry at least one C and one D.

The dog is a very deep red, so he is very likely a CC. The bitch is lighter and probably Cc^ch

4. There were no particolors, so S or sⁱ are present in both parents.

5. The bitch has greyed, so I know she has at least one G. The dog has not greyed, so he is gg.

6. The dog has thrown brown noses before but not in this litter, so the dog is certainly Bb. Because no brown noses showed up in this litter, the bitch is probably, but not necessarily, BB.

Putting all these facts together, I can write a reasonably complete list of genes for both parents of this litter:

DOG: kk, a^y a^t Bb, C(C?), D(?), Ee, gg, S(sⁱ)
BITCH: kk, a^y a^t, B(B?), Cc^ch, D(?), Ee, G(?), S(sⁱ)

When breeding this bitch again, I can avoid B&T pups by breeding her to a male who has never thrown a B&T, even when bred to a B&T bitch. (This would prove he was homogeneous for a^y a^y and did not carry the a^t gene.) To avoid clear creams, I would have to find a dog who has been bred to a clear cream (ee) bitch and produced NO clear cream pups. On the other hand, I am pretty sure that my bitch doesn't carry liver recessively, and I can breed her to known liver carriers and not worry about liver pups.

If the above type of analysis seems a bit too technical, here are some simple rules on color breeding:

If you mate two animals showing identical recessive patterns, they will breed true. (B&T x B&T = B&T). (Unless they each also carry e, which in double dose will prevent the formation of black pigment)

Recessive white spotting in its extreme form, can cover all other patterns. Clear gold recessive (ee), can cover all the "K" and "A" series patterns (solid, sable, and B&T), so you never know what a clear gold is carrying. in terms of dark pigment pattern, unless you test breed.

A black and tan with good deep tan markings will throw a high porportion of good reds when bred to a sable. (So don't sell those good black & tans as pets "just because they're black".)

A true dominant black will throw a high proportion of true blacks when bred to anything.

Two red sables may produce any color except true black or brindle.

Good luck, color breeders! Just remember the dog underneath.