Tobiano is a white spotting pattern consisting of large patches of white that typically cross over the horses topline
Breeds known to carry this mutation
Tobiano is a white spotting pattern. The large white patches usually have clean edges and often extend across the spine. The legs will often be white and partial or entire blue eyes may be observed. The head is often not affected by To, although it can still carry white markings caused by other genetic markers.
Interpretation of results
n/n: Horse does not carry the To mutation.
To/n: Horse carries one copy of the To mutation and likely has clean edged white patches on its body and extending over its topline.
To/To: Horse carries two copies of the To mutation and likely has clean edged white patches on its body and extending over its topline. It will pass To on to all of its offspring.
Brooks et al. A chromosome inversion near the KIT gene and the Tobiano spotting pattern in horses. Cytogenetic and Genome Research 2007; 119:225-230. doi: 10.1159/000112065