This is the official description of american bulldog colour from the American Bulldog Registry & Archives Breed Standard.
“Color: All white, pied, and bodysuits with white on tail, feet, head, neck and chest are acceptable. Patches can be brindle, reverse brindle, black, blue, red, brown, chocolate, fawn, blue fawn & tan. Dogs that are primarily solid black, blue or chocolate, black and tan or trindle pattern markings, fawn with a black mask, and/or any degree of merle are all disqualified from showing. (black, blue & chocolate patches are allowed but dogs that could be described as being primarily black, blue or chocolate are disqualified)
**Merle is a dilution of overall body color (black or red) with splotches of darker color giving the effect of “merling” or “marbling” not to be confused with Brindle that gives the effect of “striping”.
Pictures of our blue merle great dane below.