As a working dog, Catahoulas have been bred primarily for temperament and ability rather than for appearance. As a result, the physical characteristics of Catahoulas are somewhat varied. Catahoulas have a natural herding instinct and a unique way of working a herd. AKC describes it as creating a “canine fence” around the herd which allows the dog's master to work the herd within that circle. Herding ability and a natural working instinct are a top priority to Catahoula breeders, over and above a dog's appearance. Herding instincts and trainability can be measured at noncompetitive herding tests. Catahoulas exhibiting basic herding instincts can be trained to compete in cow/hog dog trials.