Colour genetic terms

COLOUR GENETICS EXPLAINED
(MORE OR LESS)

This page will not attempt to use all the correct terminology or include all the variations that don't seem to occur in Chesapeakes. For a very good discussion of colour genetics, with correct terms and explanations, check out Bonnie Dalzell's interesting page at Canine Coat Color Inheritance and Appearance . As usual, substitute "dark" pigment for "black". Her page does not discuss all variations, just the ones that concern borzoi breeders. Another site worth a visit isGenetics.

Colour genetics in the dog is not fully understood. Colour terminology is not standard from breed to breed. The same colour can have many variations due to coat length and type, age of dog and additional selection factors in each breed.

INFORMATION FROM PUBLISHED SOURCES WILL BE IN BROWN TYPE,
MY OWN INTERPRETATIONS IN BLUE.

AGOUTI OR A SERIES	ALLOWS OR RESTRICTS THE FORMATION OF DARK PIGMENT
A	Allows dark pigment to cover the whole body. This is dominant to all other genes in the series. It can, however, be influenced by other series.
a^y	Restricts dark pigment. Variable in expression. Can produce a clear tan/yellow or red colour with varying amounts of dark pigment. Dogs with this gene are often darker at birth than when adult. Remaining dark pigment is most often seen on the dorsal area. There are often hairs with dark tips. This pattern is recessive to A but dominant to both genes below it. However, this pattern seems to be influenced by the tan-point pattern. a-y/a-y could produce the shaded at birth deadgrass & sedge dogs which later have clear or almost unshaded colouring. a-y/a-t might produce dogs that are shaded as adults.
a^g	Agouti or "wild" colour. This is an interesting pattern. Named after a south american rodent which shows the multibanded hairs that are characteristic. This is seen in certain wild canines. In domesticated breeds, wolf-grey German Shepherds and Elkhounds carry this gene. A quick "pluck and look" test in our kennel shows it is possible that Chesapeakes carry this gene, though it might be a combination of the a-y/a-t causing the banded effect. It is difficult sometimes to tell if the hair is multibanded or just tipped with a different colour.
a^t	The tan-point pattern. Pups are born dark with only small areas of tan, if any. They then lighten with age. There is a range of expression- from tan feet, eye spots and other small areas to a dog that matures with only a dark torso. Beagles and foxhounds show this patterning with the addition of white. The tan-point pattern is recessive to others in the A series. This pattern is found in the breed. Two different types are shown on the colour chart.

THE B SERIES THIS SERIES PRODUCES BLACK OR BROWN PIGMENT

B The dark pigment will be black. However, this does not mean that the dog's coat will be black. Dark pigment can be restricted by genes in other series. If the dog has a black nose, it is B. All researchers agree that the B-b series is very clearcut. Black is dominant to brown.

b Any dark pigment will be brown. Like black, the dog will not necessarily be brown, the colour may be influenced by other series. Two brown dogs CANNOT produce black except in the case of mutation. Mutations are extremely rare, mismating is a much more common explanation of unexpected colours. Chesapeakes carry only brown. Often people will refer to dark markings on a sedge or deagrass Chesapeake as "black". This is incorrect and comparing hairs to that of a truly black dog will show that the chessie hairs are very dark brown. This extremely dark brown (liver) is seen in some German Shorthairs. In dim light they look black.

THE C SERIES CONTROLS THE DEPTH OF COLOUR

C Allows the full depth of pigmentation.

c^ch Chinchilla dilution. This works more on yellow/tan than black, giving black and silver German Shepherds, etc. However, it also works on brown/liver and is possibly the gene which produces light deadgrass and the whole range of brown shades that are found in Chesapeakes.

c^dor c ^e Extreme dilution. This is controversial, not all researchers accept its existence. Some feel that the the almost white Labradors and occasional "white" Chesapeake can be explained by c-ch/c-ch.

THE D SERIES CAUSES DILUTION OF DARK PIGMENT

D Allows dark pigment to form. Most dogs carry DD.

d Causes "blue" dilution. This is found in "blue" Danes, Doberman's and with b causes the mouse-gray Weimeraner colour. If Chesapeakes carry this gene, it could explain a few dogs that have a strange "gray-brown or taupe" colouring. In Dobermans, many feel that the blue dilute dog has a poor coat.

THE E SERIES ALLOWS OR RESTRICTS THE EXTENSION OF DARK PIGMENT

Em This is usually considered the dominant gene in this series. (Read Bonnie Dalzell's page for her thoughts- very interesting.) It produces a darker muzzle on light coloured dogs. The mask seems to be very common in light coloured Chesapeakes.

E Full extension of dark pigment as dictated by the A & B series. Dominant to both e-br & e

e^br This produces the brindle pattern, stripes of dark pigment on a yellow/tan background. Highly variable in expression. On the colour chart is a picture of a Chesapeake showing brindle striping on a light background. Her one litter proved that she also carried tan-point pattern.

e This restricts the dark pigment, producing a clear yellow/tan or red colouring. Chesapeakes that are born a clear deadgrass may carry this gene. The only way to be certain would be breeding records that showed deadgrass to deadgrass breedings producing brown pups. If dark pups are produced, it would show that one was a-y, the other ee. Records from crossbreedings of deadgrass chessies to yellow labs or golden retrievers (both known to be ee) producing black or brown pups would also answer the question.

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THE B SERIES	THIS SERIES PRODUCES BLACK OR BROWN PIGMENT
B	The dark pigment will be black. However, this does not mean that the dog's coat will be black. Dark pigment can be restricted by genes in other series. If the dog has a black nose, it is B. All researchers agree that the B-b series is very clearcut. Black is dominant to brown.
b	Any dark pigment will be brown. Like black, the dog will not necessarily be brown, the colour may be influenced by other series. Two brown dogs CANNOT produce black except in the case of mutation. Mutations are extremely rare, mismating is a much more common explanation of unexpected colours. Chesapeakes carry only brown. Often people will refer to dark markings on a sedge or deagrass Chesapeake as "black". This is incorrect and comparing hairs to that of a truly black dog will show that the chessie hairs are very dark brown. This extremely dark brown (liver) is seen in some German Shorthairs. In dim light they look black.

THE C SERIES	CONTROLS THE DEPTH OF COLOUR
C	Allows the full depth of pigmentation.
c^ch	Chinchilla dilution. This works more on yellow/tan than black, giving black and silver German Shepherds, etc. However, it also works on brown/liver and is possibly the gene which produces light deadgrass and the whole range of brown shades that are found in Chesapeakes.
c^dor c ^e	Extreme dilution. This is controversial, not all researchers accept its existence. Some feel that the the almost white Labradors and occasional "white" Chesapeake can be explained by c-ch/c-ch.

THE D SERIES	CAUSES DILUTION OF DARK PIGMENT
D	Allows dark pigment to form. Most dogs carry DD.
d	Causes "blue" dilution. This is found in "blue" Danes, Doberman's and with b causes the mouse-gray Weimeraner colour. If Chesapeakes carry this gene, it could explain a few dogs that have a strange "gray-brown or taupe" colouring. In Dobermans, many feel that the blue dilute dog has a poor coat.

THE E SERIES	ALLOWS OR RESTRICTS THE EXTENSION OF DARK PIGMENT
Em	This is usually considered the dominant gene in this series. (Read Bonnie Dalzell's page for her thoughts- very interesting.) It produces a darker muzzle on light coloured dogs. The mask seems to be very common in light coloured Chesapeakes.
E	Full extension of dark pigment as dictated by the A & B series. Dominant to both e-br & e
e^br	This produces the brindle pattern, stripes of dark pigment on a yellow/tan background. Highly variable in expression. On the colour chart is a picture of a Chesapeake showing brindle striping on a light background. Her one litter proved that she also carried tan-point pattern.
e	This restricts the dark pigment, producing a clear yellow/tan or red colouring. Chesapeakes that are born a clear deadgrass may carry this gene. The only way to be certain would be breeding records that showed deadgrass to deadgrass breedings producing brown pups. If dark pups are produced, it would show that one was a-y, the other ee. Records from crossbreedings of deadgrass chessies to yellow labs or golden retrievers (both known to be ee) producing black or brown pups would also answer the question.

COLOUR GENETICS EXPLAINED(MORE OR LESS)

COLOUR GENETICS EXPLAINED
(MORE OR LESS)