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WHITE
SPOTTING - S GENE:
The "S" series alleles appear to be
incompletely dominant. In dogs it is thought there are four alleles that
deal with white spotting:
~~ "S"
- 'solid/self color'. Most dogs that are
homozygous for "S/S" have no white hair at all, or possible a tiny
amount, like a white tail tip.
We need a
photo of a self border collie ( no white at all )
~~ "s^i"
- 'irish spotting'. This involves white spotting on most parts of the
coat, but not crossing the back beyond the shoulders. This color pattern
is evident on the Border Collie that have the white collar.
New research
has proven that the white
undersides of the Border
Collie is dictated by a different gene.
~~ "s^p"
- 'piebald'. The white is more extensive than irish spotting, and often
crosses the back with spots and stripes.
~~ "s^w"
- 'extreme white piebald'. A dog that is homozygous for "s^w" will be
almost entirely white. This allelic pair is also responsible for the
"color headed" white dogs. Often times, along with a colored head, there
will also be a colored spot near the tail.
The white factor
gene is a simple autosomal recessive and can be carried by a border
collie that appears to be non white factored. There is no way to tell
for sure until you breed it. In order to control too much white, don't
breed two known white factored dogs together, but breed a white factor
to a non white factor or breed two non white factored dogs together for
the best results.
If
you want to control the amount of white, one needs to watch out for
white over the shoulder, back & loin areas. The back leg
is another way to watch for white factor. You want the white, inside &
outside of the back leg, to be below the hock to avoid producing too
much white. The hock is the bend of the back leg. When the
white begins to go up the hind leg past the hock, it indicates the dog
carries the white factor gene. If you breed two white factored
mates together it produces at least some pups that will be pie bald,
extreme white or pattern white puppies. Commonly included in high
white border collies is the various degrees of excessive white on the
head. All excessive white on the head can contribute to deafness. You
want the colored area to cover the ears. One needs to be careful and
not breed two split faced dogs together as well. Two full colored
masked dogs offer the best results of avoiding too much white on the
face.
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