They are generally represented as being strong and tough. In November 2019, the American Bulldog was added to the American Kennel Club (AKC) Foundation Stock Service (FSS). The AKC added the American Bulldog to the FSS on November 11, 2019. The American Bulldog is a stocky, well built, strong-looking dog, with a large head and a muscular build. Colors, while historically predominantly white with patches of red, black, or brindle, have grown in recent years to include many color patterns including black, red, brown, fawn, and all shades of brindle. The color conformation is quite varied, but solid black or any degree of merle is considered a cosmetic fault, and a blue color is a disqualification by the National Kennel Club Breed Standard. The color conformation is quite varied, but solid black or any degree of merle is considered a cosmetic fault, and a blue color is a disqualification by the National Kennel Club Breed Standard.