T O B I A N O
Tobiano is probably the most well-known of the white patterns in horses. It is often lumped in with KIT mutations, although it is an inversion of KIT and not actually on the same locus. It is, however, close enough on the same chromosome to interfere with KIT's function and acts as if it is a mutation of the gene.
The tobiano pattern is most often said to cross over the spine. This tends to be true for many tobiano horses. The white patterning generally appears to start dorsally and spread downwards towards the legs. Many tobiano horses will have flashy leg markings. Tobiano itself does not seem to express with facial markings and blue eyes are a debatable topic.
Some have thought that the tobiano gene is incomplete dominant, adding more white and other factors when homozygous. However, genetic testing has shown this to be untrue. A heterozygous tobiano can sometimes have more white and other expressions such as cat tracks or halos. It just depends on the particular horse's expression of the pattern.
The tobiano pattern is most often said to cross over the spine. This tends to be true for many tobiano horses. The white patterning generally appears to start dorsally and spread downwards towards the legs. Many tobiano horses will have flashy leg markings. Tobiano itself does not seem to express with facial markings and blue eyes are a debatable topic.
Some have thought that the tobiano gene is incomplete dominant, adding more white and other factors when homozygous. However, genetic testing has shown this to be untrue. A heterozygous tobiano can sometimes have more white and other expressions such as cat tracks or halos. It just depends on the particular horse's expression of the pattern.
ToTo or nTo