Understanding and Caring for Donkeys and Mules

Mule Terminology, Characteristics and Differences

Caucasian girl petting donkey in field
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There are estimated to be 50 million donkeys (Equus asinus) and as many mules worldwide. They can be used for such applications as riding, driving, flock protection, companion, breeding, and training calves. Donkeys and mules are not small horses. They have anatomical and physiological differences compared to horses and their care requires special consideration. Structural differences compared to horses mean that they require specialized tack and harness for riding and driving.


  • Jack: Male donkey
  • Jennet or Jenny (both pronounced the same): Female donkey
  • Donkey gelding: Castrated male donkey
  • Mule: The offspring of the mating of a jack with a mare (female horse)
  • Hinny: The offspring of the mating of a stallion (male horse) with a jennet

Mature animals can be further designated into the following classifications based on height measured at the withers:

  • Miniature: under 36 inches
  • Small Standard: from 36.01 to 48 inches
  • Large Standard: over 48 inches and under 54 inches for females; over 48 inches and under 56 inches for jacks and geldings
  • Mammoth: 54 inches or over for females and 56 inches or over for male

Anatomical Differences

  1. An obscured jugular furrow (the place where blood samples are taken or tranquilizers are given). The cutaneous coli muscle is much thicker than in the horse and hides the middle third of the jugular vein. It is easier to find the upper third of the jugular.
  2. The nasolacrimal duct of the donkey is located on the flare of the nostril rather than the floor of the nostril as it is in the horse.

Nutrition and Pasture Management

Donkeys allowed to graze freely on rich pastures may be prone to obesity, laminitis (founder) and hyperlipidemia (excess of fat in the blood). When calculating the energy demands of your donkey, it is important to know that their body weight cannot be estimated using a girth weight tape intended for horses. Body condition scoring of donkeys will also require a different mindset from that used with horses since donkeys deposit fat somewhat differently than horses.

Donkeys can be alternated with cattle and sheep on pasture. This management helps maximize pasture usage and reduces the occurrence of parasites since the parasites are not generally shared between species. Sheep and/or cattle grazing pastures after donkeys consume the remaining grass along with hatched larvae that have migrated from stool clumps up to the grass blades. Donkeys commonly create an area where they can take dust and/or sand baths during warm weather.

Donkeys and mules should always have access to clean water and salt. Loose salt is preferred over a salt block since it will consume a greater volume of loose salt than from a block, especially in below zero degree temperatures. Most animals will consume anywhere from 10 to 25 liters of water per day. Snow will not provide these animals with enough water to meet their needs. Care must be taken to ensure an unfrozen water supply in ambient temperatures below 0°C.

Genetics and Breeding

Horses have 64 chromosomes, while donkeys have 62. When horses and donkeys are mated, the mule offspring have 63 chromosomes. The gestation period in donkeys is 12 months on average, but it may vary from 11 to 14 months. Despite being considered sterile, mare mules and mare hinnies will have estrus cycles. These cycles can be regular, or erratic and variable. Female hinnies and mules can be used as embryo transfer recipients but care must be given to the compatibility of donor and recipient. There have been documented cases of fertility in the female mule but not the female hinny. A report from Morocco indicates that a mule mare produced a foal with 62 chromosomes. The cells of the mule mare were a mosaic, some carrying 63 chromosomes while others carried 62. The foal has 62 and is believed to be fathered by a donkey. This is the fourth female mule to be confirmed to be fertile.

Intact male donkeys and mules can be quite "stallion-like" or aggressive in behavior. If they are not being used for breeding purposes or as a teaser, it is highly recommended that they are castrated. Castration must be performed by a veterinarian.


Donkeys and mules can also be infested by ectoparasites (skin parasites) such as flies, lice, ticks, mites, and warbles. For further information on Lice on Horses refer to. www.omafra.gov.on.ca/english/livestock/horses/facts/info_lice.htm.

The internal parasites that affect donkeys and mules are typical for other equid species and, therefore, the recommendations for control and treatment are those that we use for horses. However, lungworms are reported to be more common in donkeys than horses. A comprehensive parasite control program should include pasture management and environmental sanitation, and regular anthelmintic wormer administration. Performing routine fecal egg counts will help to determine the efficacy of treatment and control programs. Anthelmintics should be chosen conscientiously and their use should be rotated slowly to decrease the occurrence of resistance. A slow rotation of wormers is recommended (the same wormer for a year or more). Your veterinarian can help to determine the correct parasite control program for you.


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Authors: Heather McClinchey MSx; Jeffrey Sankey, BSc, Ontario Veterinary College, Unversity of Guelph, Guelph, Ontario, Canada, and Dr. Bob Wright, Ontario Ministry of Agriculture and Food, Fergus, Ontario, Canada