The Difference Between True Albinism and White-haired Animals

Albinism is the condition of being an albino. This means that there is a lack of the pigment melanin in the skin, eyes, and hair.

In humans, albinism has a recessive inheritance pattern, and 1 in 10,000 people are affected.

It takes two copies of the gene in one individual in order for the recessive condition to be expressed (a homozygote).
If an individual carries only one copy, they will be normal. Partial albinism can occur. Albinos are present in most species of animals.

Deep inside cells of the body, albinism results from the inability to convert tyrosine, an amino acid (protein building block) into the melanin pigments that colour skin, hair and eyes. This defect is due to a lack of the enzyme tyrosinase.

It is important to understand the difference between true albinism and white haired animals. True albinos have a complete absence of pigment, whereas the white-coated animal may often have odd-eyed color (one brown and one blue) or brown eyes, and the rim of the eyelids or lips etc. may have some dark, even black pigment. There are coat color variations such as merle (dilute) in some species such as the dog, where the pigment concentration is subnormal.

In horses, a lethal form of albinism exists, inherited as a dominant gene (only one copy is needed to show the effects). Most horses are white-coated animals with light (wall) eyes or odd-eyes rather than true albinos, but non-lethal full albinos do occur.

Note that roan-coated horses are not considered a dilute coat, even though their color looks washed out because normal white hairs are interspersed with dark hairs.

In cattle, albino is recessive. An extreme condition called Chediak-Higashi syndrome occurs in humans, mink, and mostly Hereford breed cattle. Here incomplete albinism is associated with severe malfunction of the immune system's germ fighting cells. Also in Herefords, a partial albinism condition is associated with inborn eye defects, even though vision can be normal. In Shorthorn cattle, a congenital (inborn) blindness is associated with white haircoat (not albino).

White-haired cats with odd eyed (one eye blue) or both eyes blue commonly have hearing deficits. These cats are not necessarily albino. Sometimes deafness occurs in only one ear in white dogs and cats.

In dogs, dark coat color is dominant over albino, so it is a rare trait, but when present it may be associated with nervous system or eye problems. Dogs can also inherit Waardenburg syndrome; associated with deafness, white coat, and blue or heterochromic (more than one color) eye color. It is seen in bull terriers, collies, dalmations, and great Danes. Note that in dogs, white or merle coats are dominant genes.

Albino and white animals are more prone to skin cancer and sunburn, so if your horse or pet will spend much time outdoors, check with your veterinary team regarding safe ways to reduce exposure to sunlight.