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White Chest Spot |
Article excerpts used with permission from Dr. Sheila Schmutz | Photos and captions by Bethany Manderson | ||
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melanocytes migrate down from the spinal column during embryo genesis not
all animals complete this process by birth or thereafter. In dogs, it is
therefore not uncommon to see white toes on an otherwise black or red
dog. This is probably more a random event than the result of a specific
allele. Another common "white spot" on dogs occurs on the
chest. This must again be a site where melanocyte migration occurs very
late in fetal development and a cold or other developmental delay
prevents the completion of melanocyte migration. It may be that the rate
of melanocyte migration is itself inherited.
In some dogs a white chest spot occurs. Various Breed Standards mention this as a fault. This is likely simply incomplete pigment migration in the particular individual, and not an inherited trait. Such small amounts of white on the chest or on the toes do not seem to be caused by mutations in MITF....MITF is a critical gene in the pigmentation pathway . The Pigmentation Pathway The pigmentation pathway shares many genes with other pathways. Therefore mutations in some of these genes will affect coat colour, will also affect neurological function, immunological function, fertility, etc. Yet another pathway which can be affected is appetite. ".... the melanocytes are migrating down from the neural crest derived cells along the spinal column and brain. It is not surprising that dogs of many breeds have missing pigment on a spot on their chest or a toe ... these are the last places that pigment cells migrate in the dog. A lack of pigment in these spots isn't really inherited, it more likely means the dam had a cold for a few days during the gestational period." Dr. Sheila Schmutz conducts genetic research at the University of Saskatchewan, Canada. The full articles and illustrations can be found on her website. Website: http://homepage.usask.ca/~schmutz/ (Please type Dr. Schmutz's website address into your browser to visit). |
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A small white spot on the chest is not faulty in the Canadian Weimaraner Breed Standard
Also seen is a white spot at the base of the pastern/ back of the foot as shown here. However the sparse, silver-tipped hair in this area sometimes gives the illusion of a white spot. |
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