What's a Hinny?

Mules are the product of a male donkey and a female horse. On the flip side, a hinny is the offspring of a male horse and a female donkey. Hinnies aren't nearly as common, but if you saw one you probably wouldn't know it.

Amy McLean is an equine reproduction specialist at the University of California-Davis and a board member of the American Mule Association. She says unless you see one born, it takes a trained eye to determine the animal is a hinny and not a mule.

"In my opinion, the face has more of a "dish" to the forehead, the ears tend to turn sharper. The idea that they're longer, they're disproportionate and things like that is not completely true," says McLean. "We did find when we were measuring, the hinnies to be closer to the donkeys in having the same underline and same topline ratio, meaning the back's the same length as the belly."

Hinnies are highly valued in countries such as Brazil, Colombia, and Portugal for ranching and as pack animals. McLean says they seem to be hardier and have a calmer temperament than mules.

So why are hinnies not as popular here in the United States? One obstacle is getting the male stallion to mate with a jenny, the female donkey.

"The other big obstacle is having a jenny that will conceive with a hybrid embryo," says McLean. "There's different ideas on why it might be harder for a jenny to come in foal with a hinny embryo versus a donkey embryo. Some of that goes back to possibly the pH of the uterus of a donkey. So, it's harder to breed them, and people who have tried, they haven't had a lot of success."