Tobiano (Coat colour pattern Horse)
The Tobiano pattern is characterised by large white patches with defined edges or sometimes with a lighter pigmented fringe. Often the head is coloured and white patches extend over the back to the other side.
The pattern is occurs in many breeds and is probably the most common.
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- Big white patches with distinct edges.
- Usually have a coloured head and white patches often reach over back.
- Tobiano pattern may obscure Frame Overo or other patterns.
- Horses with two copies of the variant (T/T) usually have an increased amount of white.
- Although rare, mostly/completely solid horses can be positive for Tobiano. They may be called “cryptic” or “hidden” Tobianos, and have small markings in the face or socks.
- Tobiano is found in many different breeds.
Genotype and Lab Report
Inheritance: incomplete autosomal-dominant
→ Incomplete means that horses with only one copy of the variant (n/T) will show a less pronounced phenotype than horses with two copies of the variant (T/T).
n/n = No Tobiano mutation
The horse shows a solid colour.
n/T = One copy of the T-variant
Pattern with distinct edges and big patches. Often coloured head (maybe with white markings).
T/T = Two copies of the T-variant
Pattern with distinct edges, big patches. Very similar to heterozygous (n/T) individuals. Maybe with a larger amount of white.
Brooks, SA., Lear, TL., Adelson, DL., Bailey, E.: A chromosome inversion near the KIT gene and the Tobiano spotting pattern in horses. Cytogenet Genome Res 119:225-30, 2007. Pubmed reference: 18253033. DOI: 10.1159/000112065.
Further information is available at Online Mendelian Inheritance in Animals.