Tri-coloured (archaic: ''oddbald'') refers to a horse with three different coat colours in a

pinto Pinto is a Portuguese language, Portuguese, Spanish language, Spanish, Sephardi Jews, Jewish (Sephardic), and Italian language, Italian surname. It is a high-frequency surname in all List of countries and territories where Portuguese is an officia ...

spotting pattern of large white and dark patches, usually bay (a reddish colour with a black mane and tail) and white. This colouring is also commonly called

skewbald Skewbald is a colour pattern of horses. A skewbald horse has a coat made up of white patches on a non-black base coat, such as chestnut, bay, or any colour besides black coat. Skewbald horses which are bay and white (bay is a reddish-brown colou ...

(referring to a horse with a spotted coat that is white and any colour other than black). In modern usage in

British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...

, skewbald and

piebald A piebald or pied animal is one that has a pattern of unpigmented spots (white) on a pigmented background of hair, feathers or scales. Thus a piebald black and white dog is a black dog with white spots. The animal's skin under the white backgro ...

(black and white) horses are collectively referred to as ''coloured'', while in

North American English North American English (NAmE, NAE) is the most generalized variety of the English language as spoken in the United States and Canada. Because of their related histories and cultures, plus the similarities between the pronunciations (accents), v ...

, the term ''pinto'' is used to describe the colour pattern. The colour of the horse's skin underneath its coat alternates between dark or pink, depending on the dark or white overlying hair colour. Some animals also exhibit colouration of the irises of the eye that match the surrounding skin (blue eyes for white skin, brown for dark). The underlying genetic cause is related to a condition known as

leucism Leucism () is a wide variety of conditions that result in the partial loss of pigmentation in an animal—causing white, pale, or patchy coloration of the skin, hair, feathers, scales, or cuticles, but not the eyes. It is occasionally spelled ' ...

Genetically Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working i ...

, a coloured horse begins with a solid base coat colour. Then the horse has an

allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

for one of three basic spotting patterns overlaying the base colour. The most common coloured spotting pattern is called

tobiano Tobiano is a spotted color pattern commonly seen in pinto horses, produced by a dominant gene. The tobiano gene produces white-haired, pink-skinned patches on a base coat color. The coloration is almost always present from birth and does not c ...

, and is a

dominant gene In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

. Tobiano creates spots that are large and rounded, usually with a somewhat vertical orientation, with white that usually crosses the back of the horse, white on the legs, with the head mostly dark. Three less common spotting

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

s are the frame and splash

overo Overo refers to several genetically unrelated pinto coloration patterns of white-over-dark body markings in horses, and is a term used by the American Paint Horse Association to classify a set of pinto patterns that are not tobiano. ''Overo'' is ...

genes, which create a mostly dark, jagged spotting with a horizontal orientation, white on the head, but dark or minimally marked legs. The sabino pattern can be very minor, usually adding white that runs up the legs onto the belly or flanks, with "lacy" or roaning at the edge of the white, plus white on the head that either extends past the eye, over the chin, or both. The genetics of overo and sabino are not yet fully understood, but and can appear in the offspring of two apparently solid-coloured parents, whereas a tobiano must always have at least one tobiano parent.

References

"Introduction to Coat Color Genetics"
''from'' Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis. Web Site accessed January 12, 2008 {{Equine coat colors, sp=com Horse coat colors

See also

References