Page 903 - The Veterinary Care of the Horse

VITILIGO

VetBooks.ir Vitiligo is the name given to the condition where patches of skin lose their pigment and

become pink in colour without any obvious explanation.

Causes

The cause is not fully understood. The colour of a horse’s skin and coat is determined by the
amount and type of melanin it contains. Melanin is a pigment released by special cells in the

skin called melanocytes. Its purpose is to protect the skin from harmful ultraviolet radiation.
In Appaloosas it is thought that the condition may be hereditary. In other cases, various
theories include toxicity, an autoimmune reaction, nutritional or metabolic imbalances.

Clinical signs

The patches of pink skin tend to develop in areas where the external skin surface meets a

mucous membrane, e.g. around the:
• lips

• muzzle (Figure 18.46)

• eyes (Figure 18.47)

• vulva
• anus

• sheath.