A horse is the improper occasion for saying “dog” partially because it has hooves rather than claws. It also has the wrong kind of teeth and doesn’t bark. Note that although the size of a horse is different from most dogs, it is still irrelevant: if we see a Saint Bernard as big as a horse, we would still call it a dog.
Fur
Barking
Four legs
Canine teeth
Claws
Tail
Size
Color