Page 87 - JRT Magazine - 2023 Issue 2
P. 87
Pigments
The diversity of colors in dogs occurs
from just two pigments: eumelanin and
phaeomelanin. Each of these pigments has
a ‘default’ color that can then be modified
by various genes. Eumelanin is, by default,
black pigment, but variation in color occurs
because genes modify eumelanin to create
other colors/shades such as liver, brown,
chocolate, Isabella, and gray. Genes modify
the pigment into these other colors/shades
by preventing the production of full-
strength eumelanin.
The ANKC, FCI, KC and AKC Breed Standards
for Jack Russell Terriers/Russell Terriers are very
similar in terms of the description of acceptable Range of shades produced by eumelanin (affects coat, eye, and
colors. White must predominate with black and/ nose color).
or tan markings. At first glance, it seems quite Image from doggenetics.co.uk, with permission.
simple, but there are many nuances. The tan can
range from almost cream/lemon to a deep red Phaeomelanin is the second pigment that
chestnut/mahogany. The black can exist with determines canine coat color. This pigment
white only (bicolor) or with tan (tricolor). is red with a ‘default’ color of yellow.
Phaeomelanin creates reds that range
from a light cream to a deep red, including
Development of DNA testing for dogs’ traits
allowed breeders to better understand the general the colors of orange, gold, and tan. Genes
color genetics of dogs, and here we will cover control the intensity of phaeomelanin,
those specific for Jack Russell Terriers/Russell making the color stronger or weaker.
Terriers. Phaeomelanin is produced only in the
coat and affects only hair color, whereas
eumelanin also affects eye and nose color
along with the coat.
Range of shades produced by phaeomelanin (affects coat color
only).
Image from doggenetics.co.uk, with permission.
Groups of various genes control the whole
process of pigment production. Genes
determine which pigments (eumelanin
versus phaeomelanin or both), how much,
and where exactly they will be produced.
A Worldwide Magazine for the Jack Russell Terrier / Russell Terrier • Issue 2/2023 | 87
