Is there a chance that a mule may reproduce if bred?

It is not uncommon for female mules to come into estrus and for male mules to display signs of teasing other female equine when in estrus. Most mule owners will castrate male mules, and some will even spay female mules (remove the ovaries) in hopes of changing behavior associated with estrus or aggression. A mule is a cross between a male donkey (jack) and a female horse (mare). A hinny is the reciprocal cross, a female donkey (jenny/jennet) and a …