Now that the borax is on it, it's highly unlikely you can do anything with it. Coyotes STINK and need washed and degreased during the tanning process. You could TRY to rehydrate the hide, scrub the borax off, and proceed with tanning. But, I seriously doubt you'll be able to get all the borax out of it. The borax will really cause problems with the PH in the tanning process. Still, you don't have much to lose.