Mules and hinnies differ in various ways, but they are classified generally and in the show world as mules. A mule or hinny can only be produced by breeding a horse with a donkey. These hybrids are sturdy and intelligent equines who have a longer work life, stronger hooves and greater endurance than horses. Mules and hinnies tend to be more resistant to disease and live longer lives than their parents.
The parentage of a hinny differs from that of a mule. Breeding between a female horse, or mare, and a male donkey, or jack, will produce a mule. When a female donkey, also known as a jenny or jennet, and a stallion or male horse are bred, the result is a hinny. Mules are hybrid equines with their own distinctive traits and familiar characteristics of their sires, who are donkeys, and their dams, female horses. Hinnies are also hybrids; however, although some look like their horse mothers, they rarely resemble their donkey fathers. Hinnies vary in appearance more than mules do.
Mules have been said to have the body of the horse with extremities of a donkey, whereas hinnies have the body of a donkey and the extremities of a horse. Because a donkey mare is smaller than most horses, hinnies are generally smaller than mules. A hinny's ears are shorter than a mule's, his mane and tail are thicker and longer and his hooves are rounder. Hinnies differ from each other more than mules do, from being almost identical to a horse, to being mule-like or nearly indistinguishable from a donkey. Mules have long ears, a thin, short, possibly upright mane and a tail which in part has shortish hairs but also long hairs like a horse tail. The mule's tail can be much fuller and longer than a donkey's. Her legs, like the donkey's, are straight, and she has small, hard, straight-sided hooves.
Mules possess hybrid vigor. They are typically stronger than horses and are much longer-lived with much longer working lives. They seldom become sick or lame, and they tolerate extremes of temperature. Mules can live on frugal food rations, have great stamina, are resilient and sure-footed. The American hinnies are said to lack hybrid vigor, and it has always been recognized that they are smaller than mules (although this may partly be due to their being carried in a smaller womb), less strong and with less stamina and hardiness.
Intelligence and Temperament
Mules are more intelligent, perceptive and sensitive than horses. They learn quickly and are adept at assessing situations. Mules who have handlers and trainers who are smart and respectful tend to be "obliging, kind, patient, persevering, calm, tolerant, sensible, loyal, affectionate, playful -- and also proud, jealous and calculating," according to the British Mule Society. Hinnies are more donkey-like in temperament, in part because they are raised by donkeys. However, hinnies are generally quieter, less curious, more compliant and less independent and adventurous than mules. They prefer to avoid trouble rather than confront it.
Visible differences between mules and hinnies can be subtle and are not consistent enough to be used to identify one hybrid from the other. A method that may be more reliable than others is behavioral. If you release a mule or hinny into a mixed group of equines, the mule tends to choose horses for company, as she was raised by a horse mother. The hinny will be more likely to choose to socialize with the donkeys, because his mother is a donkey.
Maura Wolf's published online articles focus on women, children, parenting, non-traditional families, companion animals and mental health. A licensed psychotherapist since 2000, Wolf counsels individuals struggling with depression, anxiety, body image, parenting, aging and LGBTQ issues. Wolf has two Master of Arts degrees: in English, from San Francisco State University and in clinical psychology, from New College.