Horses, Donkeys, and Mules

Horses, Donkeys, and Mules

Reading Time: 6 minutes


By Dr. Stephenie Slahor – Here’s a short course in the three different worlds of three very different equines — horses, donkeys, and mules. Their various characteristics, foibles, and behaviors are interesting, and knowing more about them will give you a better ability when being around them.


For tens of thousands of years, horses in the wild lived on open, flat plains in large herds. Threats to the herd or even an individual horse meant running or even stampeding to escape. This defense not only gets the horses away from the threat but also influences how horses eat. Running on a full stomach would not be easy, so wild horses grazed most of their day, keeping their stomachs never empty and never over-full.

Even after centuries of domestication, horses still spook, shy, run, or panic at something that scares them. Remember that horses are farsighted, so if something appears “suddenly,” a horse might react with a jump, ready to run. So, when working around horses, make your presence known by whistling, whispering, humming, singing, or talking softly to let the horses know that you are approaching or are nearby.  

Suddenly poking out your hand to pat a horse can spook a horse, too, so avoid jerky movements. 

There are over 350 horse breeds, but the vast majority of them act the same. 


Donkeys have served us as pack animals for centuries, but larger donkeys do serve as transportation for humans, too. 

Donkeys look quite different from horses and mules. They have short, upright manes and no forelock between their ears. The hair around their eyes is usually lighter in color and softer in texture. Their tails are smooth-haired, with a little switch of hair on the end. Their legs are fairly straight. Their ears are long and can swivel to focus toward sounds — even sounds you don’t hear, so those ears augment their vision. Interestingly, the ears play a role in body temperature, too — the ears are filled with blood vessels that radiate heat away from the donkey’s body.   

Donkeys need less food than horses. Domesticated horses might overeat if food is readily available. Donkeys don’t usually overeat.   


In the wild, donkeys occupied arid and desert lands rife with loose sand, uneven terrain, rocks, hills, sharp cactus and plants, and scarce water. The shortage of water kept donkeys traveling in small groups, not large herds as horses do. Donkeys also learned that desert terrain could produce injury if they stampeded away from danger as horses do. Donkeys are more controlled in their reactions to danger. They stop and ponder which of their three reactions is best — to flee, attack, or stay put. Female donkeys tend to protect one another and their young by forming a circle around the young or vulnerable and then kicking out at a threat. Mature, intact male donkeys can actually be aggressive. In the wild, they would be ousted from the group because of potential harm to the foals.   

Donkeys adapt well to heat and can host a normal body temperature between 96.8 and 104 degrees F, depending on the time of day and the air temperature. Donkeys don’t like cold weather and can be hypothermic if their body temperature goes below 95 degrees F.   

As with horses, make soft noise or talk when approaching a donkey, and be gentle with handling or leading a donkey. Keep your hand close to the halter when holding the lead rope rather than tugging a long length of lead rope. That tugging may put your donkey into a full stop! 

There are over 160 donkey breeds, most of them quite tolerant and gentle when trained.  


Mules are the original 4×4 hybrid, well known for being intelligent and sure-footed.  

The mule is the foal of a male donkey and a female horse. Mules probably originated way back in time when horse herds and donkey herds might have encountered each other — and Mother Nature did the rest. (If a male horse bred with a female donkey, the resulting hybrid would be a hinny, an equine with many of the characteristics of mules, but generally smaller in size because of the maternal donkey genes and the womb size of the mother donkey, which affect the baby’s growth during gestation. A hinny has a head more like a horse than a donkey, ears like a horse, and a mane and long tail like a horse. But a hinny is less strong and vigorous than a horse or mule.)  

The horse has 64 chromosomes, the donkey has 62, and the hybrid mule or hinny has 63 chromosomes. Mules and hinnies cannot reproduce because their genes do not originate from the same species. Reproduction requires an even number of chromosomes.   

Mules vary widely in color and weight, depending on their parents. There are mini-mules weighing around 50 pounds, and mammoth mules weighing well over 1,500 pounds. It all depends on the size and weight of the parents.

Anatomically unique, a mule has a head thicker and wider than a horse, legs straighter than a horse, hooves smaller and narrower, ears long like a donkey, and a tail and mane a little less full than a horse’s. The structure of the larynx and pharynx of donkeys and mules is somewhat different and narrower than those of horses. That difference is what creates that distinctive “hee-haw.”   


Mules and hinnies have greater endurance than horses and are more resistant to disease. They usually live longer than typical horses.  

Interestingly, if a hinny is released into a group of horses and donkeys, it will likely socialize with the donkeys, being raised by a donkey mother. Mules are more likely to choose horses for company because of being raised by a mare.  

After their workday, mules and donkeys love to roll in the dirt. Mules recover from work faster than horses and are ready to go the next day. Horses might not be so eager. 

Although mules live about seven to 10 years longer than horses, they are like donkeys in that they mature later. Most mules are not used for long days of work or trail riding until they are at least six years old.  

Sure-footedness is the hallmark of mules, somewhat due to body strength, but more accredited to the fact that a mule’s eyes are farther apart than a horse’s eyes, giving the mule the ability to see all four of its feet at the same time. A horse can see only its front feet. Being able to see and figure out where to put its feet is what gives a mule sure-footedness. If you watch a mule walk and the terrain is fairly rock-free, you’ll see that the front hoof impacts the ground and that the back hoof on the same side will land right in that same impact point — something horses don’t do.  

Mules have a narrower rib cage than horses so most riders find a mule more comfortable for riding.  That’s why mules are often used for outdoor adventures such as backcountry camping, hunting, and fishing trips. For over 100 years, mules have been used on the Grand Canyon’s trails by prospectors, miners, and tourists!   

Mule hooves are smaller than a horse’s hooves, but harder and more durable, and they rarely crack. Not all mules are shod, but, on snow or ice, they may have shoes with nubs that grip. 

Mules are agile! They can strike with a hoof, even if someone is holding up a different hoof — something to remember when cleaning a hoof or shoe. Mules can stand on two legs — one front foot and one back foot on the opposite side, and they can sit like a dog, and jump from a flat-footed start. Yes, indeed, they are agile!  

Alas, some people think of mules and donkeys as “stubborn,” but they are definitely not. Mules could flee, but that donkey side of the family adds in the other two survival modes — attack or stand your ground. Donkeys and mules ponder their course of action and, when they stop and refuse to move, they are using the stop as a defense against the perceived challenge or fright. It may look like stubbornness, but the animal is assessing the situation. So, if your mule or donkey balks, resist the urge of yanking on the lead rope if you’re leading the animal, or repeatedly kicking or spurring if you are astride. Your equine is figuring out something, but probably will not be forced into action by you. You’ll have to wait.    

Mules are more intelligent and perceptive than horses, and they learn faster. If they are overloaded, they might lie down until the load is lightened. Mules tend to avoid bad places on a trail. They have a good sense of direction, even in the dark. Interestingly, most mules don’t get barn sour so they don’t usually hurry “back to start” when being worked or on a trail.

Mules can travel longer distances than horses, perspiring less, and needing less water than horses would. There must be at least a two-degree increase in a mule’s body temperature before it perspires, but their hair can absorb the perspiration and put it back into the skin.  

And now you have some extra knowledge to add to your collection of equine information! 

Originally published in Countryside November/December 2021 and regularly vetted for accuracy. 

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