Winning Ticket a brown Thoroughbred with the classic brown coloring Open Source
The color brown in horses has long been a source of ambiguity. Some registries handle brown as a separate color, while others consider all browns to be dark bay. Adding to the confusion, researchers, even as late as 2003, theorized that the darkest brown horses were actually black horses with mealy. It became apparent however, when the recessive allele at agouti (a) was located, that these dark horses with brown noses and flanks didnâ€™t test as black but as bay. Because no other agouti alleles were located, at the time, it was generally accepted that brown (even the almost black variety) was just a darker version of bay. This changed when Pet DNA Services of Arizona isolated the mutation that causes brown.