Tricoloured horse

Tri-coloured (archaic: oddbald) refers to a horse with three different coat colours in a pinto spotting pattern of large white and dark patches, usually bay (a reddish colour with a black mane and tail) and white.

In modern usage in British English, skewbald and piebald (black and white) horses are collectively referred to as coloured, while in North American English, the term pinto is used to describe the colour pattern.

Then the horse has an allele for one of three basic spotting patterns overlaying the base colour.

The most common coloured spotting pattern is called tobiano, and is a dominant gene.

Three less common spotting genes are the frame and splash overo genes, which create a mostly dark, jagged spotting with a horizontal orientation, white on the head, but dark or minimally marked legs.