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White coat coloring can increase a cat or dog's chances of being born deaf. The genetics of color can be complicated in pets, but this article will explain how the whiteness of the coat relates to hearing loss. Keep in mind, there are many things that can cause congenital deafness (that only means present at birth it may be hereditary or environmental) and white coloring isn't the only cause. This article isn't going to explore all the possible causes, but only look at the interesting relationship between white pets and hearing loss or deafness.

The gene for white coloring in dogs was identified on gene number 20. So far, 85 breeds of dogs have reported cases of congenital deafness. All breeds have the potential for congenital deafness, but breeds with white pigmentation are at greater risk. Deafness is often associated with the merle gene or the piebald gene in dogs, yet not all breeds with these genes are reported to be affected.

In cats, deafness is associated with the dominant white gene. In addition, white cats (with that dominate gene) are also more likely to have one or more blue eyes than cats of other colors. The chance of deafness in cats increases with the number of blue eyes, so cats with two blue eyes are more likely to be deaf than cats with one blue eye. Longhaired cats also have a higher rate of congenital deafness than shorthaired ones. Three studies that looked at 256 white cats found that 12.1 % were deaf in one ear, and 37.9 % were deaf in both ears making a total of 50 % of white cats affected by at least partial deafness. That's a awful large percentage.

So why exactly does being white put a pet at risk of being born deaf? Deafness is caused when part of the blood supply to the cochlea degenerates, causing the cochlea nerve cells to die. Even though these pets are considered to be born deaf, this isn't quite accurate. It turns out that the damage occurs soon after birth, when the ears are still closed. The exact mechanism of why the blood supply deteriorates isn't well understood at this time, but appears to be associated with a lack of pigment-producing cells in the blood vessels.

Learn more about this author, Catherine Leigh.
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