The sesame coat color in Shibas has been a mystery for some time. For years, it was thought to be a result of one red allel and one black and tan allele at the Agouti mocus. (More on that later). But Ay/At dogs rarely bred true sesames.

Then the “agouti”, or “wolf” allele was discovered, and people thought that Aw/At dogs were the key to sesames.

A new study done in Russia in 2021 discovered a new variant of the red allele and called it Ays. It is a shaded red – not as dark as Aw, but darker than Ay. Here is the paper released by the Russian team that did the work on characterizing this new allele: https://www.mdpi.com/2306-7381/9/5/222/htm.

UC Davis can test for this new allele in our dogs! https://vgl.ucdavis.edu/test/agouti-dog

I’ll add more info in a bit – but for now – here is a summary of how the new alleles interact to form the colors in Shibas. (Back and tan Shibas are thought to be ASIP-BBB1. (Recessive black is not found in Shibas). It COULD be that the red sesame (aka-goma) is Ays/At, while the black sesame (kura-goma) is Aw/At. It would be interesting to see if this was the case in Shikoku as well.