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Murf
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30-09-2011, 03:22 PM

Why does lack of pigment cause deafness

I know the reason certain white breeds boxers/ ebts dalmatians are more prone to deafness as they dont have pigment in the ear .
But why does this cause deafness
What has pigment got to do with hearing ???
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GSD-Sue
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02-10-2011, 12:51 AM
Don't know the answer but know the white gene is also linked to deafness in cats. Has no links with many white coated dogs though. I shall be interested in the answer to this question as well.
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Murf
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02-10-2011, 01:00 AM
Horses too i have read ..
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Jenn~n~Luke
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02-10-2011, 01:23 AM
It has something to do with the nerve endings in the inner ear dying, usually in the first week or so after the pup is born.

The cause of the deafness associated with the white colour is the absence of pigment cells in the inner ear resulting in a loss of sensory hair cells at about 6 - 8 weeks of age. The shortage/absence of pigment cells is also the cause of the white coat and unpigmented third eyelids (haw). Generally speaking, the more pigment in the coat the lower will be the risk of deafness, but all predominantly white dogs are at risk of being deaf.
hmm..there seems to be some debate about the age in which the problem occurs.
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Morewuffthan
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02-10-2011, 08:34 AM
As far as I can tell from literature - to hear sound depends on having tiny little hairs in the ear in the cochlea. Like any other part of the body these tiny nerve hair cells require specific amounts of essential nutrients to remain healthy and if the blood supply is insufficient to the parts that are involved the tiny neural hair cells are not supported and they die off causing the hairs to die. This is what George Strain thinks happens on the basis of studies so far.

"deafness results from the type of hair cell loss that is a primary event with unknown cause. In breeds of dogs carrying the piebald or merle genes and breeds of cats carrying the white gene, the hair cell loss is secondary to degeneration of the cochlear blood supply"

Congenital hereditary sensorineural deafness
Dr George Strain

http://www.lsu.edu/deafness/VetClinNA.htm

The article he wrote above contains links in it to figures showing the ear structure in detail.

http://www.lsu.edu/deafness/VetJDeaf2004.pdf
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Sara
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02-10-2011, 10:38 AM
Doesn't have to be a predominantly white coat, ticking also causes the lack of pigment in the inner ear (namely ACDs, Dals, Setters, Pointers and JRTs) Also It's not predominantly white coat, but pigment-less (for lack of a better word) coats. Samoyeds, Bichons, Westies, and white Poodles have no issues with deafness, because they have dark pigment, however white Boxers, white Pit Bulls and Double merle's have low pigmentation, therefore are at risk of none in the inner ear.

Even having colour on or around the head doesn't mean the dog wont be deaf, but there's a better chance of it with a white head than a coloured head.
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Wozzy
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02-10-2011, 10:46 AM
Fascinating stuff as my sister had a deaf white boxer. The breeder said she wasnt deaf but my sister soon learned when she got her home that she was. Maybe this links in with the timing of the hair cells dying. I assume up until that point the dogs can hear?
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Sara
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02-10-2011, 10:52 AM
Everything I've ever been told, or read says that they lose the ability to hear before, or slightly after their ears open... but obviously there seems to be a little question there. BAER testing is done between 6 and 8 weeks old, so they would have to lose their hearing before then.
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Wozzy
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02-10-2011, 10:57 AM
Originally Posted by Sara'n'Scout View Post
Everything I've ever been told, or read says that they lose the ability to hear before, or slightly after their ears open... but obviously there seems to be a little question there. BAER testing is done between 6 and 8 weeks old, so they would have to lose their hearing before then.
Ah right, so they would essentially be deaf right from the start...
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Carole
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02-10-2011, 12:05 PM
The cause of the deafness associated with the white colour is the absence of pigment cells in the inner ear resulting in a loss of sensory hair cells at about 6 - 8 weeks of age. The shortage/absence of pigment cells is also the cause of the white coat and unpigmented third eyelids (haw). Generally speaking, the more pigment in the coat the lower will be the risk of deafness, but all predominantly white dogs are at risk of being deaf.
Finn's breeder (a vet) told us this too. So when we first saw Finn and picked him we had to wait til he was older to find out if he was going to be deaf.
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