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Posted by AmyB on 4/20/2008, 8:40 pm, in reply to "Does the white coat pose genetic problems?"
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Deafness is a problem in the breed. It is because of the lack of pigmentation, not simply the white coat.
What is being done?
BAER test pups to see if they are full-hearing, bi-laterally deaf, or unilaterally deaf.
Don't breed unilaterally or bi-laterally deaf pups as they will defently pass on genetics for deafness.
When two full-hearing dogos are bred resulting in a full or mostly deaf litter, don't repeat that breeding as the genetic combination of that pairing didn't work well.
That is what should be done but isn't always done. Here are some articles on deafness so you will have a better idea on deafness in breeds that lack skin pigmentation (and other genetic deafness issues):
http://www.lsu.edu/deafness/genetics.htm
And here is a power point presentation Dr. Strain did with color examples that I found really great: http://www.lsu.edu/deafness/DeafTalk.ppt
It's kinda long but is pretty clear. Deafness occurs in breeds with certain pigmentation patterns - the presence of white hair in the coat increases the chances of deafness. Two pigmentation genes in particular are often associated with deafness in dogs: the merle gene and the piebald gene. Deafness, which usually develops in the first few weeks after birth while the ear canal is still closed, usually results from the degeneration of part of the blood supply to the cochlea (the stria vascularis). The nerve cells of the cochlea subsequently die and permanent deafness results. The cause of the vascular degeneration is not known, but appears to be associated with the absence of pigment producing cells (melanocytes) in the blood vessels. All of the function of these cells are not known, but one role is to maintain high potassium concentrations in the fluid (endolymph) surrounding the hair cells of the cochlea; these pigment cells are critical for survival of the stria.
Here is another more detailed conference presentation by Dr. Strain: http://www.lsu.edu/deafness/Tufts.htm
Hope that helps.
Amy B
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