We wish to thank Jeanette Gower for kindly giving us permission to use the following text from her book. Jeanette Gower
is a foremost authority on horse colour genetics, a respected judge and an equine studies lecturer. As this is copyrighted material, you may not reproduce this excerpt including images without Jeanette Gower's express permission.

Horse Colour Explained by Jeanette Gower

By far the most easily recognised pinto is the tobiano. The others are sabino, overo and splashed white. With a little observation and practice it is easy to distinguish and identify most examples.

Strictly speaking, tobiano (pronounced to-bee-ar-no) and any other broken colour or pied appearance is not a colour, but a white pattern interacting upon any one of the normal base colours, duns, dilutes, taffy, roan or grey. The terms 'skewbald' and 'piebald' are obsolete, for they do not give an indication as to the type of white marking present on a pied horse, nor its genetic make-up. Instead we now talk of black tobiano, grey tobiano and so on.

A major feature of the tobiano is that white will appear to start somewhere along the spine (generally neck, withers, rump or tail, in which case the tail will be two-coloured - rarely will other pinto types have a bi-coloured tail) and descend vertically. In a few cases the white may only be seen in the tail or withers, and on the legs. This is the only pinto colour that can have a dark head without white on it.

More frequently the white will cross the spine in at least three places. If it extends (descends) deep enough, the white will join up with the white of the legs. In very white horses, the colour is reduced to patches known as 'shields'. These commonly occur on the breast, flank, head and buttocks. The shielded tobiano is very susceptible to skin cancers in areas with limited protective hair covering such as the anus and penis. I know of no all-white tobianos. Even where colour is reduced to the extreme, some colour always remains on the head. This is nature's attempt to protect the eyes. These individuals are known as 'medicine hat' tobianos.

The tobiano is a relatively simple pattern, for the colour is inherited as a simple dominant in true Mendelian fashion. Tobiano horses are To^TTo^T or To^TTo⁺, whilst normal-coloured horses are To⁺To⁺.

The modifying genes which control the extent of the white markings in the tobiano are probably present in all horses, but rely on the presence of To^T to express themselves. Modifying genes are minor genes which occur independently of the major genes, and can only express themselves in the presence of a major gene.

Quick Guide to the Tobiano

• Tobiano is a dominant pattern of white patches which appears to spread vertically down from the spine, and upwards from four white legs.
• Face markings are the same as on normal horses.
• Tobiano must have one tobiano parent, even if incompletely marked.
• Homozygous tobiano will produce 100% tobiano, and have both parents tobiano.
• Blood marker analysis is now available to detect homozygosity in a potential breeding horse.

Features of the Tobiano

• Body white crosses the spine
• Body white appears to descend vertically
• Four white legs with irregular edges
• Ermine spots with dark hoofs
• Patches of colour around the chestnuts

NOTE:
Of course there may be individuals which are exceptions in one of the above areas, but these have a preponderance of other features which still identify them as tobiano.

Gradients of Tobiano

Horse Colour Explained by Jeanette Gower
Copyright Jeanette Gower, 1999. First published in Australia in 1999 by Kangaroo Press. ISBN 0 86417 906 5

You can reach Jeanette Gower at her website http://www.Chalani.net