MUCHO BRAVO HAVANEZERS
SORRY, OP DIT MOMENT ALLEEN NOG IN HET ENGELS!The inheritance of coat color in Havanese.
Every dog owes his coat color to the combined activity of a number of units of heridity, or genes. The gene has a characteristic chemical composition and a configuration which reproduce themselves accurately and identically in each generation. The genes are located in linear order (called locus, plural loci), like a string of unequally spaced beads, in microscopic structures known as chromosomes. Every normal cell of every individual of every species of mammal has a fixed and characteristic number of such chromosomes. Each mature sex cell ready to engage in the process of fertilization has one-half of the number of chromosomes found in any other type of cell in the same individual. In all cells -except the mature sex cell- there are pairs of chromosomes. In the simplest form of heredity (according to Mendel's law) there occurs one type of gene that comprises both members of a gene pair. In the ordinary pair of Mendelian units the one of the pair which masks or conceals the other is called dominant, and the one which is masked, or concealed, recessive.
The most important "loci" for the Havanese are: A-locus, B-locus, E-locus, S-locus.
But you should know about the C-locus, D-locus, G-locus, and T-locus as well.
On the A-locus there are the following important genes for the Havanese (in order of dominance):
- A : allows the distribution of dark pigment over the whole body surface
- ay : restricts markedly the areas of dark pigment and in its most complete expression produces a clear sable dog.
- at : produces the bicolor varieties (like the black & tan)
Because all these genes come in pairs (one of the father and one of the mother) the following combinations on the A-locus are possible:
- AA : black Havanese (homozygoot)
- Aay : black Havanese, carrying the gene for sable
- Aat : black Havanese, carrying the gene for black&tan
- ayay : sable Havanese (homozygoot)
- ayat : sable Havanese, carrying the gene for black&tan
- atat : black&tan Havanese (always homozygoot!)
The possibilities are:
- B: this gene produces black coat color, determined by a certain quantity and quality of dark-pigment granules in both the cortex and the medulla of the hair.
- b: is the recessive form. b allows the reduced degree of pigment formation observed in the liver (chocolate-brown) series of dogs.
- BB : black Havanese, without a gene for the chocolate-color
- Bb : black Havanese, carrying the gene for chocolate
- bb : chocolate Havanese, with chocolate nose etc.
A dog with BB or Bb has a BLACK nose. A dog with bb has a chocolate (or livercolored) nose, lips, eyerows and feet. A dog with bb can not have anything black!
Now, in combination with the A-locus:
The E-locus is very important in the Havanese!
- AA/Aay/Aat + BB/Bb : black Havanese with black pigmentation
- AA/Aay/Aat + bb : chocolatecolored Havanese with chocolate pigmentation.
- ayay/ayat + Bb/Bb : sable Havanese with black pigment
- ayay/ayat + bb : chocolate-sable Havanese with chocolate pigment
- atat + BB/Bb : black&tan Havanese with black pigment
- atat + bb : chocolate & tan Havanese with chocolate pigment
The two most important genes are:
The combinations again are: EE, Ee and ee
- E : allows the formation of dark (black or brown) pigment, evenly over the whole coat
- e : the bottom member of this locus, in which no dark pigment can be formed in the hair, leaving it a clear and evenly distributed shade of red or yellow
The other genes are:
Em and ebr are very rare with Havanese. There are sable Havanese with the Em-factor. They have a black mask. And the ones with bb do not have a black mask, but a chocolate one.
- Em : gives a black mask.
- E : see above
- ebr : stands for brindle, and gives bands of dark pigment, more or less regular in outline or extent, on a background of tan or yellow ( f.i. the boxer). It is not the same as sable!
- e : see above
NOW, in combination with the A- en B- locus:
(an A. or B. etc stands for homozygoot or heterozygoot. In this case A. stands for AA, Aay, or Aat ay. stands for ayay or ayat, and the B. stands for BB or Bb)
- A.B. + EE/Ee : black Havanese with black pigment
- A.B. + ee : clear (white, cream, champagne, red, golden etc) Havanese with black pigment.
- A. bb + EE/Ee : chocolate Havanese with chocolate pigment
- A.bb + ee : clear Havanese with chocolate pigment
- ay.B. + EE/Ee : sable Havanese with black pigment
- ay.B. + ee : clear Havanese with black pigment
- ay.bb + EE/Ee : chocolatesable Havanese with chocolate pigment
- ay.bb + ee : clear Havanese with chocolate pigment
A Havanese atat B. ee shows sometimes on the "normal" tan- places a lighter color than the rest of his coat. This is only visible when a puppy is very very young. Later you can not see any difference anymore.
- atat B. + EE/Ee : black&tan Havanese with black pigment.
- atat B. + ee : clear Havanese with black pigment
- atat bb + EE/Ee : chocolate & tan with chocolate pigment
- atat bb + ee : clear Havanese with chocolate pigment
Bad pigment on a clear dog has nothing to do with the Bb or bb genes!
THIS WAS THE BASIC.
We can go on with the other loci.
This is one of the most interesting of the coat-color loci in dogs, and also in Havanese!
- S: the "highest" in this serie, is responsible for a solid-colored coat, with no white or with very minute spots on the toes or chest.
- si : known as "irish spotting". Few and definately located white areas. The pattern consists of white spots or streaks in one or more of the following locations: muzzle, forehead, chest, belly, one or more feet and the tail tip.
- sp : known as "piebald spotting". One may find dogs varying from those which show a condition similar to irish spotting in appearance to others which have only 15 to 20 per cent of their coat pigment. (F.i. Beagles show range of expression of the piebald gene).
- sw : causes extreme piebald spotting.
(again; only the genes that are important for the Havanese!)
A dog with ee is in principal always clear (light-colored). And when it is more dark gold or dark red, it becomes a lighter color under the influence of the cchcch genes. The same for the black&tans; the tancolor becomes cream-colored.
- C : this is the gene for full depth of pigmentation. . This is the condition observed in the deep rich pigmentation of goldenbrindles, dark tans or reds, or deep, absolutely black or liver varieties.
- cch : this is the second member of the series and is also called "chincilla". This gene has a distinctly greater effect in reducing the red-yellow pigment than it does on the black pigment.
For this reason, it becomes apparent chiefly, if not entirely, in light-pigmented areas.
The chinchilla factor has no influence on the black or grey color; it possible can have some influence on the sable color.
Of course the combinations again are DD, Dd and dd.
- D : the dominant member, causes intense pigmentation. NO dilution.
- d : stands for dilution of the color. F.i. black becomes blue, brown becomes silver.
Most dogs fall in the group with the D.
One characteristic frequently seen in dd animals is the peculiar flat, dull quality of the color, wether it is dark or light. It is there right away when the are born ; it does not appaer later (f.i. the Weimaraner).
Dogs with GG are or become more light-colored than those who have Gg in there genes.
- G : The G-gene appears to be at least partly dominant and changes a puppy born of a uniform dark color in the direction of increasing grayness or paleness. It produces a progressive graying from birth until old age or throughout life.
- g : there is no lightening or progressive graying; the dog remains dark.
Appearently some Havanese do have the ticking factor. They are born f.i. black and white, or red/sable and white, and later they get in the white areas little spots. The most well-known breed with the ticking factor is of course the Dalmatian. But also the Cocker Spaniel and the Shih Tzu do have this factor.
- T : produces in white (only white!) areas of the coat flecks or ticks of color, usually referred to as "ticking".
- t : no ticking; the white areas remain white.
NOT important for the Havanese!! (but interesting to know about)
M : stands for merle. Occasionally one or both eyes are light blue. In some breeds (f.i. Collies) MM animals are badly deformed or handicapped; they are usually deaf and blind, and are often sterile.
m : no merle gene. m produces the uniform pigmentation.
It's obvious now that the coat color in a dog is very complex. However it isn't as mysterious or unpredictable as it looks. It certainly isn't as arbitrary as some people think, and hopefully you now understand there surely is logic in the inheritance of coat color.
Gene pairs on all the loci together will determine the color.
Each puppy gets one gene from each locus of the sire and one gene from each locus of the dam.
So f.i. when the father has on the A-locus atat, and the mother has ayay, all the puppies will have ayat. That means they look like sable Havanese, and they are carriers of the black&tan gene.
Except when they have on the E-locus ee, then they look like clear Havanese, but they carry the ay and at gene, so they still can produce colored puppies.
Well, it is a complicated thing, the inheritance. But hopefully this explanation will help you a little bit to understand some of it.
The Havanese is a colorful breed, and that makes it so much fun!!!
*The inheritance of coat color in dogs by Clarence C. Little, Sc.D.
*Genetics of the dog by Malcolm Willis, B.Sc.,Ph.D