Importance of full pigmentation as it concerns an American Bulldog's health

Here's one risk factor for dogs who do not get full pigmentation. An AB's muzzle, lips, and eyes should ideally have full black pigment.

"Deafness is caused by lack of pigment in particular parts of the inner ear, and can be unilateral (just one ear) or bilateral (both ears). It is commonly claimed that dogs with white ears are always deaf, but in fact it's been shown that whether or not pigment is visible on the outer ear does not affect whether or not the dog can hear. In other words, a dog may have coloured ears but still be deaf, and a dog with white ears will not necessarily have any problems, because the part of the ear that is affected by the lack of pigment is not externally visible. However, Dalmatians with ear or head patches do appear to have a lower rate of deafness than those with no patches at all."

Admittedly, I am not an expert, but logic leads me to believe that the less visible pigment an AB develops, the higher the chances that it wouldn't develop the necessary pigment in the inner-ear, which, to make things more difficult, cannot be visually confirmed.

Full pigmentation is an attribute of a healthy dog.

To me, this all goes back to the breed standard for American Bulldogs. Even what some may consider to be "cosmetic" faults are in reality quite often defects that can and will have negative effects on health of a given dog or its progeny (offspring). Breeders need to be extremely conscious of such genetic defects when breeding such dogs.

http://doggenetics.co.uk/problems.html