MDs are trained to think of the modal cause: when you hear hoofbeats, imagine horses rather than zebras.

Wonder why they did not call it a "Hebra". Must be something to do with anti-Semitism.

2: No, it's the patriarchy. A hebra is a when the father is a horse and the mother is a zebra.

Wikipedia has an entry on zorses, which are not a new phenomenon (there's a picture of a zorse taken in 1899 on that page). Also an entry on zeedonks and on zebroids in general. Apparently there's never been a successful cross between a male horse and female zebra.

Of related interest: according to this wikipedia article on hinnies (offspring of a male horse and a female donkey; mules are the reverse), which comports with some things I've heard I've heard from mule drivers:

Other than size, there are some minor differences that occur frequently between mules and hinnies. The head of a hinny resembles that of a horse, more so than mule heads do. Hinnies often have shorter ears, although they are still longer than those of horses, and more horse-like manes and tails than mules do. They often come in horse colors, as the male parent often determines the color of the coat. Therefore, mules usually have donkey coat colors. Certain traits, like the popular gait that some horses and donkeys possess, seem to pass more readily though the male parent. Therefore, many people have tried to produce gaited hybrids by using gaited male horses on female donkeys in hopes of creating gaited hinnies.