“I would like some information about mules. Are the parents always a male donkey and a female horse, are they always sterile, and can mules be either male or female?” The staff of the Newton Falls Public Library had some rudimentary knowledge about mules, but not as extensive as our patron needed.
The library lacked books specifically on mules, but does have an assortment of materials on horses. We looked for information about equines and first examined The Complete Equine Veterinary Manual: a comprehensive and instant guide to equine health by Tony Pavord & Marcy Pavord and Illustrated Dictionary of Equine Terms compiled by New Horizons Equine Education Center. The latter defines mule as a hybrid, the mating of a mare with a jack (male donkey or ass), Mules originated in Spain and are seldom fertile.
Encyclopedias are always great sources of basic information, so we next looked at the Encyclopedia Americana, 2006 edition. The article, in volume 19 page 609, stated a mule is “the offspring of a jackass and a female horse. The offspring of a stallion and a jenny (female ass) is known as a hinny. Both mules and hinnies are ordinarily sterile. Female mules are rarely fertile . . . there seem to be no records of fertile male mules.” Both mules and hinnies are similar to the sire in build and appearance, but are usually approximately the size of the mother. Returning to Illustrated Dictionary of Equine Terms, we found that their definition of a hinny agrees that it is the progeny of a female donkey and male horse.
We informed our patron that the parents of a mule are always a male donkey and a female horse, the offspring can be male or female, and the females may not be sterile. Our patron was curious if hinnies could reproduce. Our reference materials did not have the answer, so we expanded our search to online resources. The website TheMules [www.themules.net] noted “There have been no recorded cases of any fertile male hinnies, however there has been one single documented case of a fertile female hinny.” The site did not give any verifiable details or citation of this case.
Readers interested in more equine information may check out a variety of books ranging from The Affordable Horse: a guide to low-cost ownership by Sharon B. Smith to Wild About Horses: our timeless passion for the horse by Lawrence Scanlan. Horse & Rider magazine is also available to be borrowed.