Why is it... that in some breeds white dogs are blind (or have other defects) when others in the litter would not?
Bare with me.. cuz this is just coming off the top of my head... and sorry gr8danegirl but I'm using you as an examply (dont take that offensivly)
If two harlequin danes are bred... and have white deaf puppies... why arent others in the litter affected? Is deafness hereditary? Would the parents have it as a recessive genes? Why are only prodominately white puppies be deaf? Would a black puppy carry a deaf gene?
And is it the same for all white dogs? Boxers, westies, shepherds, dobies, schnauzers...
White dobermans may not have white eyes, but they definitely are a type of albino. They have a complete lack of pigmentation, everywhere except the eyes, which are commonly blue. The gene that causes albinism in dobermans is not the same gene that causes white dogs in other breeds to suffer from deafness/blindness. As far as I know, while albino dobermans are sensitive to light, they suffer from neither blindness or hearing problems, no more so than your average normally pigmented doberman does.
I think the white dog deafness/blindness is a developmental defect, for some reason. Those areas do not form normally.
Those dogs that are white due to lacking pigment in skin, and possible eyes are deaf because parts in their inner ears do not develop as a result of the lacking pigment. This is why those with blue eyes are more likely to be deaf. This also goes for cats I have been told.
Dogs that are white, but not due to lack of pigment do not have this problem because they have pigment.
I don't even think it's 'albino' dogs. I think its something else, personally. Darn you Mericox, now I have to look it all up, I can't stand not being informed!
Are those puppies considered to be albinos, even? They have less pigmentation, but the two pups in gr8danemom's litter do have pigment, spots of black on their body. They have far less pigment than their littermates yes.
Ok so I found this site which is easy to understand
Apparently the dogs that suffer from hearing problems, their white coloration is more linked to patterning than albinism.
Two white dogs, west highland white terriers and samoyeds, they are all white, have pigmentation (black noses, eyes) but dont suffer hearing loss. Their coat whitenss is not pattern related. Neither is an albino dobermans, which is a pigmentation gene, not patterning.
The harlequin gene, the merling gene, the spotting gene in dalmatians are all pattern related genes, this to me seems to be where the deafness/blindness is linked to. Apparently we don't know the how or why of it yet, it's just that way because that's how it is.
And of course theres just the general 'recessive blindness/deafness' gene that can strike any animal (or human, for that matter). An unfortunate roll of the genetic dice... kind of how the albinism gene cropped up in originially in dobermans, I guess.
***Edited By: Minniyar on 1/21/2007 10:07:24 PM*** Reason: add
"What causes a dog to lose its hearing? A lot of the same things that cause hearing loss in humans. Genetic defects can cause a dog to be born deaf; this is known as congenital deafness. A dog can also lose its hearing due to an ear infection, injury to the ear, or may experience gradual (or sudden) hearing loss due to old age. Exposure to loud noise can cause temporary or permanent hearing loss, as can certain drugs.
The most common cause of congenital deafness is pigment related. (There is some talk about a recessive gene as well, but most researchers do not believe this is the case.) Some dogs have white coats, but still have pigmented skin (Samoyeds, West Highland Terriers, and White German Shepherds fall into this category). Although they have white fur, they have black noses and eye rims (their fur is actually not pure white, but a very light buff color). Other dogs normally have colored coats, and white trim (this includes Dalmatians; the white is actually not their real coat color, the "spots" are). The "trim" comes from areas of unpigmented (pink) skin, which produces white hair. If there is unpigmented skin in the inner ear, the nerve endings atrophy and die off in the first few weeks of the puppy's life, resulting in deafness. Please note that you cannot tell the color of hairs in the inner ear by looking at any visible part of the dog's ears (including the hair around the ear canal). Although many dogs with white hair on their ears will be deaf, many deaf dogs have colored ears as well.
Hearing loss affecting both ears is called Bilateral Deafness. A bilaterally deaf dog is completely (or mostly) deaf in both ears. Hearing loss occurring in, or affecting only one ear, is called Unilateral Deafness. A unilaterally deaf dog has hearing loss in only one ear and has full hearing in the other ear."
***Edited By: danemom on 1/21/2007 10:39:03 PM*** Reason: r