Birdcatcher spots

Markings on horses usually are distinctive white areas on an otherwise dark base coat color. Most horses have some markings, and they help to identify the horse as a unique individual. Markings are present at birth and do not change over the course of the horse's life. Most markings have pink skin underneath most of the white hairs, though a few faint markings may occasionally have white hair with no underlying pink skin. Markings may appear to change slightly when a horse grows or sheds its winter coat, however this difference is simply a factor of hair coat length; the underlying pattern does not change.

On a gray horse, markings visible at birth may become hidden as the horse turns white with age, but markings can still be determined by trimming the horse's hair closely, then wetting down the coat to see where there is pink skin and black skin under the hair.

Recent studies have examined the genetics behind white markings and have located certain genetic loci that influence their expression.

In addition to white markings on a base coat, there are other markings or patterns that are used to identify horses as with Appaloosa, Pinto or Brindle, as well as artificial markings such as .

Facial markings are usually described by shape and location. There may be more than one distinct facial marking and if so, will be named separately. Occasionally, when a white marking extends over an eye, that eye may be blue instead of brown, though this is not consistently seen in all cases.

Common facial markings are:

Additional terms used to describe facial markings include the following:

Leg markings are usually described by the highest point of the horse's leg that is covered by white. As a general rule, the horse's hoof beneath a white marking at the coronary line will also be light-colored ("white"). If a horse has a partial marking or ermine spots at the coronary band, the hoof may be both dark and light, corresponding with the hair coat immediately above. Where the Leopard gene is present, the hoof may be striped even if markings are not visible at the coronary band.

From tallest to shortest, common leg markings are:

Additional terms used to describe white leg markings include:

...
Wikipedia