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Thinking with Mules and Hinnies as Life Overlooked

by N.T. Rowan


A mule is the offspring of a female horse and male donkey. A hinny is the offspring of a male horse and female donkey.

According to Donna Campbell Smith, in The Book of Mules, mules and hinnies have been bred and used by humans for over 3,000 years and such treatment continues todaay (1). I first encountered mules and hinnies in the Greater Toronto Area, where they are bought, sold, and owned for farm work, riding, petting zoos, scientific and medical studies, and as companion animals. Throughout this webpage I will discuss how mules and hinnies can be understood as a life overlooked and what that might mean for them as individuals.

Two mules grooming each other (left). Donkeys saying hello (right). Horse (below).




Table of contents

I) Methodology Behind the Webpage

II) Meeting Mules and a Hinny

III) What are Mules

IV) Differences Between Mules and Hinnies

V) Where do Horses and Donkeys Fit in?

VI) Are Mules and Hinnies Overlooked ‘Species?’

VII) Where do Humans Fit in?

VIII) What do Mules and Hinnies do (for us)?

IX) What do we do to Mules and Hinnies?

X) Works Cited


I. Methodology

The methodology of this webpage is informed by:

  • i) my thinking through nine and a half years of experiences with mules, hinnies, horses, and donkeys and,
  • ii) wandering through scholarly databases, historical archives, my local public library, and the internet to see what other humans had to say about these equine subjects. Laurie Ricou writes in the book Salal, “I wanted – singularly, obsessively – to be alert to as many references to salal as I could” (2), and I attempt to be so with mules and hinnies.

i) thinking through my experiences with…

Ecofeminist scholar Josephine Donovan suggests “that we shift the epistemological source of theorizing about animals to the animals themselves” (305); I understand Donovan’s statement to mean that thinking about animals should be informed by those animals, but how can we do this without speaking of, as, or for other animals? Just as I would not speak for other humans, I feel that it is equally problematic to speak for mules and hinnies. While they may not have a conventionally recognizable voice, it is their individual lives and experiences that are at stake here and privileging my opinion or position does not benefit them.

Keeping such complications in mind, I have chosen to write this webpage from my encounters with mules, hinnies, donkeys, and horses. I do not claim to really know the animals that I write about, or that such a thing is even possible – especially as they are relegated to the human social construct of equine, which is really just a smaller but still similarly violent label to animal, in line with Jacques Derrida’s critiques in the lecture “The Animal That Therefore I am (More to Follow)” (400). Instead I start from the moments where equines and I have considered one another, interacted with one another, and mingled as animals with very different histories and trajectories. This strategy is one potential way into theorizing ‘the animals themselves,’ without the illusion that I can see through their opaqueness any more than they can, as Judith Butler might say (20). In other words, this is writing about subjects that offers no ‘truths,’ in all of the complications that troubling the notion of truth might suggest.

My equine experiences begin with horses, who I encountered many times over six years of riding at eight teaching stables and one family breeding farm. I rode English and Western, competed in small jumping competitions, cleaned stalls, fed horses, brought them out to pasture, worked with ‘difficult’ horses, and taught beginner riders the basics of grooming and riding. I no longer ride horses and over the course of the webpage you will learn a little bit about why.

For the last three and a half years I have had many encounters with donkeys, mules, hinnies, and a horse at one sanctuary. I have cleaned stalls, mucked paddocks, taken equines for walks in the forest, taught visitors about equines and sanctuaries, and groomed dozens of equines with varying degrees of trust in humans. Most of my encounters are now through grooming, which is important to me because I think repeated pleasant encounters with humans can be very beneficial for animals who are not at ease with humans. Some extra attention and affection for the equines that are at ease is also important. I hope that my grooming encounters make their regular vet visits feel safer and their lives a little better.

Some of my encounters with equines will be shared as personal narratives, set apart from the rest of the webpage in block quotes, like this text appears. They are meant to be read in juxtaposition with the rest of the text, struggling with the ‘official’ narrative, contradicting it, and adding to it.

Other encounters are shared in photographs that I have taken or other people have taken of me. These photographs frequent this webpage as a reminder about the real individuals that we are talking about in the text – mules and hinnies are not just symbolic ideas, but subjects of lives that we can encounter and encounter us. I do not always distinguish if the subject of the photo is a mule, hinny, donkey, or horse – the difficulty in doing so is often my point. The boundaries between these equines are fluid, unstable, and relatively thin. You might also see a few goats and sheep. The donkeys, mules, and hinnies that I know live with them and encounter them regularly as well.

The third way that encounters appear on this webpage is in the form of videos. All of the filmed footage was taken at a sanctuary that I volunteer at and all of the animals could be considered rescues in some form. In the footage I try to interact with the donkeys, mules, and hinnies as if the camera were not present. I use a cell phone camera to be as unobstructive as possible. There is a lot of standing around, hanging out, saying hi to equines I know, and just being there, with them, waiting to see what they do. Sometimes it looks like ‘nothing’ is going on, or at least to us humans anyways. That is the point. Slowing down to donkey, mule, and hinny time takes a little practice and I’d like to invite you to try it by pausing to watch the videos. Keep in mind that the donkeys, mules, and hinnies that you see have all found their forever home and will be very well cared for as they live out the rest of their lives. They will not be bought, sold, or bred again. When I invite you into my encounters with sanctuary animals, please also think about the animals that do not make it to sanctuaries.

ii) wandering in…

This webpage also includes information that I have wandered across on the public internet, in scholarly journals I accessed as affiliated with a university, in university libraries, and in my local public library. This information comes from people who work and live with mules and hinnies in many different ways and across many different contexts. I have chosen to follow the research where it takes me and track what I find interesting, replicating a wandering methodology that lingers, looks, and moves on when it gets bored – much like the mules, hinnies, and donkeys in the videos. There is a lot of places that I do not wander to and much more left to be said.


II. Meeting Mules and a Hinny

Let’s begin with a mediated mule and hinny encounter. These are the individual mules and hinny that come to my mind when thinking about equines and I invite you to try and think with them as well.


III. What are Mules

Mules and hinnies are frequently thought of as constituting different entities, as is apparent in referring to them by two different names, but we will begin broadly by thinking about mules and hinnies simultaneously. Temporarily discussing mules and hinnies as just mules is in line with Gail Damegrow’s assertion, on the website Rural Heritage, that mules and hinnies are grouped together as mules at equine sales and shows; in some contexts, hinnies semantically become mules.


I used to be nervous to go into the mule paddock. What if they got out? What if they moved too quickly? What if they nipped? These were all confusing fears to get worked up about for someone who had ridden horses for six years and handled the ‘dangerous’ ones just fine. My horse was bucking? No big deal. Wait until they stop. A horse put my entire elbow inside their mouth when I was looking the other way? Alarming, but okay. Sometimes I was wary, or nervous, but I always managed. The donkeys I’d met were even easier to get along with – most of our physical interactions were them wandering over for an ear scratch or side itch. If mules and hinnies were just a mix of horse and donkey, why should they be any different? And yet, my mind said they just were.


Scientists would probably describe mules by saying that mules, like their horse and donkey parents, belong to the phylum Chordata, the class Mammalia, the order Perissodactyla, and the family Equidae (Burnie and Wilson 226).

Mules do not have their own scientific species. They can be classified by the species Equus caballus x Equus asinus; horses are Equus caballus, donkeys are Equus asinus, and because mules have one horse and one donkey parent they count as both (Grint et al. 956). Part of mules’ overlookedness is evident in how they are thought about, or perhaps more accurately, not thought about, in scientific classification. Mules disappear when we look at individuals by considering their species. What are the ways in which they do appear?

Humans are interested in mules because of something called ‘hybrid vigour’. In the article “Mule Cognition: A Case of Hybrid Vigour?” Leanne Proops and other academics describe common perceptions of hybrid vigour by writing, “mules tend to be stronger and have better endurance than a horse, combined with the steadfast disposition and surefootedness of the donkey. Mules are capable of growing taller than either parent and of carrying more weight than a horse of the same size” (75). In other words, mules possess the best traits of the horse and the donkey in one animal and are arguably even better than their parent species. My wandering through historical archives brought me to the book A Treatise on Cattle, written by John Mills in 1776. In it Mills writes, mules “partake of the qualities of the animals from which they proceed; that is to fay, they have the frength of the horfe and the hardinefs of the afs” (277). Humans have long documented their preference for mules because of their noted hybrid vigour.



One of the defining features of a hybrid animal is that they are said to be infertile, or cannot breed. How this applies to mules has been a topic of long and contentious debate. In 1776 Mills wrote that some people believe mules cannot breed because their parents are of two different species, while others claim that mules can breed in “hot countries.” In France, mules were supposedly not allowed to breed, because if they did they would become “vicious and fpiteful” (276). According to Nancy Lofholm, reporting for The Denver Post in 2007, mules do have the capacity to breed, but they breed rarely. Lofholm writes, “in the past two centuries about 50 cases of mules giving birth have been recorded. Only two of those were proved with genetic testing.” Mules giving birth is so rare that Lofholm mentions an ancient Roman phrase, “cum mula peperit,” which means “when a mule foals,” which is supposedly the equivalent of us saying today “when hell freezes over.”

One of the first few times I was cleaning the mule paddock alone one of the mules stopped eating hay to look up and stare at me. I know that mules have a concept of hierarchy and that came to mind when I tried to figure out what to do. My mind reeled through everything I knew about hierarchy. I’d heard that staring dogs you don’t know in the eye is both a good and bad idea – bad because it will make them think you’re challenging them, and good because you won’t look weak. From personal experience nothing had ever happened when I’d stared unknown dogs in the eye by mistake so I took the chance and stared right back at the mule. If anything, I didn’t want to let them out of my sight.

After about a minute the mule walked over and stopped two feet in front of me. I stood very very still. I was suddenly aware of how big this mule was – their shoulder was almost as high as mine and their head was enormous. Their body was one lean set of muscles. If the mule wanted to, they could do some serious damage to me. As these thoughts were rushing through my head the mule continued to stare. Eventually I got out of my own head for long enough to actually pay attention to the mule, whose ears I noticed were perked forward and in my direction. This is not a sign of aggression, my years of working with horses told me. The mule was listening. Maybe they were inquisitive. Their tail was still. Their whole body was still, aside from relatively calm breathing. We watched each other for about two more minutes and then the mule just turned around and walked away.

How humans have utilized the term mule has changed over time. In 1776 Mills wrote, “all animals which owe their origins to creatures of different fpecies are generally termed mules, and accounted barren” (276). While Mills does refer to horse-donkey hybrids in that text as mules, the term mule is also applied to other hybrid animals that cannot reproduce. In 1838 Charles F. Partington classified female bees that cannot breed as “neuters or mules” (353). Partington writes that mule is a name for an animal that “will breed back to pure blood of either parent, but not with each other” (675). In other words, as is pertinent to our discussion of mules as horse-donkey hybrids, Partington would have believed that horse-donkey hybrids could breed with horses or donkeys, but not with other horse-donkey hybrids. If horse-donkey hybrids continued to breed with one of their parent species, their offspring would eventually revert to the parent species (221). For Partington this would have been true of all ‘mules,’ regardless of their parent species. Another type of mule that Partington discusses is “goldfinch-mules or canary-goldfinches” (702). Partington also writes that leopards were once thought to be lion-panther hybrids or mules, which is where they get their name; leo means lion and pardus means panther (733). In 1856 Oliver Goldsmith refers to the offspring of zebras and donkeys as mules (267). Thinking about mules as a meta-category for hybrid animals did not appear in any of the contemporary texts that I read.

In contemporary texts I saw mules classified by breed and class. Paul and Betsy Hutchins write on the website Rural Heritage that the breed of a mule is determined by the breed of their horse parent (“What is a Mule?”). I wonder if this is because while breed is a way to frequently discuss horses, breed rarely, if ever, comes up when discussing donkeys. Mules can also be distinguished by class, which is determined by what the mule is bred to do. There are: miniature or pony mules, saddle mules, pack mules, work mules, and draft mules (“What is a Mule?”).

There are two distinct markings on donkeys – black stripes on their back legs and a black stripe on their back. Sometimes this black stripe is paired with another black line across their shoulders. Together, the two lines form a t. I have heard that you can tell where a donkey’s ancestors came from if they have these markings. I’d say more than half the donkeys I’ve met have the back lines and it’s a good marker to remember who is who. Only a few that I’ve met have had the stripes and those donkeys also had the line. Other identifying features are spots, the patterns on their ears, and the colours on their faces. Mules can have these markings as well.


Mules are also classified by their assumed sex. A female mule is called a molly and a male mule is called a john (Campbell 20). This naming system is similar to how we talk about the parents of mules; in Fifty Animals that Changed the Course of History Eric Chaline writes that a male donkey is called a jack and a female donkey is called a jenny or jennet. A male horse is a stallion, or gelding if neutered, and a female horse is a mare (Chaline 73).


Carol J. Adams and others academics have produced some important scholarship on how female animals are treated because they are female and/or feminized (313), but how do we even know that these animals are female?

Saying that someone is female because they have a vagina, produce estrogen, can give birth, or any other number of reasons, would not be acceptable if we were talking about humans. While these kinds of ideas certainly proliferate in popular culture, the mainstream media, and most sectors of academia, they are problematic and do not represent the many ways that people live, or do not live, their genders, or sometimes lack thereof.

I am really excited about the kinds of ideas circulating in online nonbinary trans communities, wherein self-identification matters and we get to express the very many ways that our genders do not neatly fit into conventional categories of ‘male’ and ‘female.’ One of my favourite statements is by tumblr user nonbinaryhermione, who criticizes people who agree with the gender they are assigned at birth for sometimes acting “like it is the worst thing in the world not to assume people’s genders.” We don’t assume we know what a stranger’s name is – we ask people what their names are. Why don’t we ask people what their genders are? And yet, while I am excited about the many ways we talk about self-identification and challenging gendernormativity and assumptions, I can’t help but notice that all of this theory assumes a human subject. There is no need to even clarify – of course we are talking about humans.

What might it mean to recognize that we should not assume anyone’s gender when discussing animals that aren’t human? Mules may not know if we are calling them male or female. Even if we did try to get them to self-identify, mules probably do not have gender identities that can fit into human social constructs. They also arguably don’t have sexual orientations that can fit into human social constructions either. Nor would they understand species in ways that fit into human social constructs. So, it seems that we are applying male, female, mule, donkey, horse, and all sorts of other labels, for our benefit and meaning making systems. They matter to us. Why? What becomes possible when we continue to think about mules and other animals in fixed, essentialist, gender terms that we should hesitate and think twice about applying to members of our own species without asking first?

Sex and gender might matter when discussing mules because distinguishing by sex makes possible certain claims and actions. In 1776 Mills wrote male mules are preferable to female mules for labour and long journies because they are stronger (280). In this example, sex distinction is necessary to uphold hostile/explicit sexism. This kind of overt sexism does not appear in any of the contemporary texts that I read on mules, but it does linger in the shadows. Sex matters for horses and donkeys because we need to segregate them by sex to breed them. It is also very relevant when trying to make mule babies because horses and donkeys are rarely willing to breed together without human intervention. Sex matters because we need to know equine sex. Campbell writes, “one of the challenges of breeding the jack and mare is that the jack is often reluctant to service a mare” (104). Campbell also shares an anecdote where a donkey was attacked by horses unwilling to breed with the donkey, so the human owner split up the horses and muzzled the donkey so that donkey stopped biting the horses. When one horse refused to breed with donkeys, “future artificial insemination will solve the problem” (104). Categorizing mules by sex fits neatly into a system wherein mules are recognized as property that we create, buy, sell, own, and breed, whether they want it or not. I can’t think of anything sex categorization does that is meaningful or useful to the mules themselves.



Mule personality, and how we ought to respond to these personalities, are frequent topics of discussion in the texts that I came across. In 1776 Mills criticized mules by writing, “they are very fantaftical, and apt to kick, and their obftinancy is become proverbial” (277). Mules supposedly only kick with their back feet, and according to Mills, it is appropriate to give mules wine to familiarize them with humans and tie one of their back feet to their thigh to prevent them from kicking (280-1). Mules are still well known for kicking today; in 2008 Campbell writes, “mules have a reputation for being likely to kick, especially when their hind feet are handled” (53).

You can see some mule feet to the right.


The only ‘problem’ I have ever had with mules is cleaning their back feet. I have been told that no animal likes to pick up their feet because it puts them off balance and makes them vulnerable, so they really have to trust you to do so willingly. The mule that I’ve been working with for over three years used to kick a lot when I started grooming them. Sometimes they would kick backwards, away from their body. When you’re cleaning feet you’re standing beside a mule, so there is almost no chance this kind of kick will hit you. Once, when this particular mule was very agitated, they started kicking sideways. I was paying attention and it was generally easy to move out of the way. I have never been hit by any equine trying to kick me and I assume this is because they are kicking out of agitation or fear and just want me to go away. I have never had a mule try to go after me or injure me. I’m sure if they wanted to, they would have easily done it.

Mules usually kick when you try to pick their back foot up. Most of the time they are trying to kick out and dislodge your grip. Donkeys do this too sometimes. My method is to hold on to the foot and wait. After several kicks the mule usually stops and lets you clean the foot. I try to work very quickly to minimize their agitation. After about half a year the mule I worked with began to kick less. They might do it every now and then on a particularly irritable day, but it’s rarely more than one little half kick to just test my hand, and then they stop.



Both Mills and Oliver Goldsmith, later in 1856, write that mules need to be “broken” to train them out of their supposed natural obstinancy (Mills 280; Goldsmith 283). In a contemporary source, on the website Rural Heritage, Paul and Betsy Hutchins write, “mules are not stubborn. Neither are donkeys. Yes, if you want them to work too hard for their own well being, especially in hot weather, they will be ‘stubborn’… A mule will trust its own judgement before it trusts yours (“Why Mules?”). We might be able to understand mules better by saying that when we try to ‘break’ them or force them to do anything, mules refuse because they do not trust our judgement. Why should they?

In 1916, R.J. Day, a Second Lieutenant in WWI wrote about mules and horses, “very often the animal is put down as lazy or bad-tempered when the fault really lies with the man in whose care it is.” Furthermore, “harsh treatment should never be meted out to mules or horses, and this applies particularly to mules, who strongly resent any beating and refused to be worked as a consequence. But by kindness, coupled by a firm hand, much good work will willingly be done” (3). Similarly, in an article on Rural Heritage, Sophia Harember writes, “you can never force a mule to obey you. If you try, any compliance will be short lived. The best methods are based on explaining to the mule what you want.”


IV. Differences Between Mules and Hinnies

As noted previously, a mule has a donkey father and horse mother. A hinny is the opposite; they have a horse father and donkey mother. Does this matter?

In 1707 A.S. Gent wrote that it is better to have a male donkey breed with a female horse, rather than a male horde breed with a female donkey, because the female horse is larger and can give more nourishment to the baby, making a bigger and livelier baby mule (104). Gent referred to both potential babies as mules, but we can see traces of a hinny/mule distinction. In 1776 Mills wrote mules from a male donkey and female horse are “better” and “handfomer.” According to Mills, mules from a male donkey and female horse and mules from a male horse and female donkey “are even two different kinds” (280). In 1838 Partingon used the terms mule and hinny and wrote that a mule looks more like a donkey and a hinny looks more like a horse (283). In 1856 Goldsmith did not distinguish between mules and hinnies, but said that the animal we call a mule is preferable because they are “larger, stronger, and better shaped” (264).

On Rural Heritage Gail Damerow gives several reasons why mules might be a lot more popular than hinnies, but admits to not knowing the real reason why. Some potential reasons include: hinnies “can be less predictable in both conformation and temperament,” donkeys have smaller uteruses than horses and thus make smaller (and less desireable) hinny babies, a female donkey has a lower conception rate when bred with a male horse but a female horse’s conception rate doesn’t differ when bred with a donkey, and donkeys have a one month longer gestation period, which means that they cannot have a baby every single year.

Betsy Hutchins writes that hinnies look more like horses; they often have shorter ears, fuller tails (the tail on the right is a mule tail), and a more horse-like body and limbs than mules do. On the website Animals Maura Wolf agrees, describing hinnies as more horse-like as well. However, according to Wolf, these physical differences are so small that it would be easier to tell mules and hinnies apart by their behaviour; hinnies would prefer to be with donkeys, because they were raised by a donkey mother, and mules would prefer to be with horses, because they were raised by a horse mother.

I have only ever met two hinnies and they both happened to be miniatures, or as I find fun to say, they were mini hinnies. Neither of these hinnies has ever let me touch them, but I have observed them frequently and they have observed me. If someone had asked if they were mules or hinnies, I probably would have guessed that they were mules. I doubt that I’d ever be able to distinguish a hinny in a lineup from a mule. For all I know, some of the mules that I’ve met might be hinnies in disguise.


Amy McLean and others write, “it is my belief that there are more hinnys in the mule world than we realize because we typically group hinnys and mules together at shows. I often wonder how many times hinnys are sold as mules and the buyer is not told in fear they will not buy the animal.”


V. Where do Horses and Donkeys Fit in?

Sophia Harember writes, “the mule is expected to think and act like a horse. When it does not, it is labeled as stubborn or recalcitrant. Herein lies most, if not all, the difficulties that trouble mule handlers.”

I have been thrown off a horse three times. Two times the horse made a mistake and didn’t mean to throw me. During one of those mistakes I got a concussion and forgot about a week’s worth of time. The third time, the horse really really did mean to throw me. At the last possible second before a jump the horse jerked to the left and sped off in the opposite direction. When I did not fall off, the horse refused to stop until I was thrown. After that I could no longer ignore the agency and frustration of the horses that I was riding. I started paying more attention to the horses that had been labeled as ‘problems’ or ‘deviant.’ When waiting in line to do a jumping course, what did it mean that the horse I was sitting on tried to rub me off into a cement wall? It quickly became clear that many of the horses around me did not want to be at riding stables and did not want me to ride them, but what could they do about it?

One of the reasons that mules and hinnies are overlooked is because someone else is in the spotlight. First, our society notices horses. They are the feature of nearly all equine competitions and shows. Graceful, elegant, and supposedly eager to please, horses are our culturally favoured equine companions. Second, we might notice donkeys. They linger in the background, but nearly everyone knows what a donkey is. Many of us are even able to tell them apart from horses by sight. Finally, if we keep looking, we might even see mules and hinnies – if we even see them at all. A story about mules and hinnies is always already multilayered stories about horses and donkeys and in them the difference between horse and donkey can never quite be resolved. While this website is about mules and hinnies, you might notice that we are always haunted by their equine parents.

Harember writes that horses “react” while donkeys think and then “act.” Mules are closer to donkeys and take some time to think, but only after you have developed trust and communication with the mule (Harember).

One saying I have heard several times is when you want a horse to do something you tell them, but when you want a donkey to do something you ask them. This is supposedly because horses have hierarchy and donkeys do not. Horses will listen when told what to do if you show them that you are a competent leader. Donkeys will listen if they decide that you have asked them to do something that makes sense and is not dangerous. When working with mules, my job is to figure out if the mule is acting like a horse or a donkey. Do I tell or ask? If you tell and push too hard, sometimes the mule may lose trust in you and refuse. If you ask and give too much slack, sometimes the mule will take advantage and ignore you. The key is to watch and pay close attention. In my experience mules switch back and forth between donkey and horse, sometimes from moment to moment, and sometimes even acting like both.


Betsy Hutchins writes, “neither the mule nor the hinny is simply half horse and half donkey, but is an individual animal with completely blended characteristics, plus a few new ones belonging only to itself and not found in either parent.” Although I am sure that Hutchins is correct, I have yet to figure out exactly what these new characteristics might be. I still have a lot to learn from mules and hinnies as I attempt to sort out where their parents end and they begin.


VI. Are Mules and Hinnies Overlooked ‘Species?’

As this website is about an overlooked species, it seems worthwhile to linger on the ways that mules and hinnies fit into the term species (or don’t). As we noted earlier, horses are the species Equus caballus and donkeys are the species Equus asinus. Mules and hinnies are Equus caballus x Equus asinus (Grint et al. 956). In other words, mules and hinnies are hybrids; they do not constitute a species.


In Animal David Burnie and Don E. Wilson define species as “a group of similar individuals that are able to interbreed in the wild” (18). Mules and hinnies have small, if any, wild populations and mules and hinnies cannot breed to sustain their population because they rarely breed. However, the idea of species is a lot more contentious than this definition suggests.

According to Richard E. Richards there are over twenty ‘species’ concepts being used by academics (4) and we shouldn’t expect scientists to agree on just one to use anytime soon. Instead of fretting about this, Richards suggests that we use the ‘population lineage’ concept as our way to theoretically define species and keep all of the rest in circulation as operational concepts (13). In other words, how each academic defines species should be determined by what they are doing with this definition. For example, if we are looking to conserve species, we should use a definition of species that works with conservation. When we are talking about species theoretically, as we are to some extent here, Richards proposes that thinking about species in terms of population lineage works best.

Population lineage “reflects the basic evolutionary assumption that species taxa have two dimensions, synchronic and diachronic. They exist at a particular time as population of organisms, and over time as a lineage of ancestors and descendants” (Richards 145). Arguably, mules and hinnies are synchronic and diachronic. They do exist in a particular time as a population of organisms. If by population we mean an increasing or stable size group, then mules and hinnies count. Mules and hinnies are not going to go away anytime soon, even if they do need our intervention to keep them around. Furthermore, mules and hinnies also have a ‘lineage of ancestors and descendants’ – just their ancestors are in a different species and their list of descendants is smaller than would be for other species. Obviously I am stretching these definitions and coming up with loopholes that might allow mules and hinnies to count as species. This is because if mules and hinnies are a species, they do not function like other or conventional species do. Maybe that has more to say about our human concept of species than about mules and hinnies.

Can you spot the mule?

In 1776 Mills wrote, “for the antients pofitively affert that the mule is able to procreate at feven years, and that he does actually procreate with the mare (a). They alfo tell uf, that a mule is capable of conception, though it never brings its fruit to maturity. Thefe things, which throw a veil of darknefs over the real diftinction between animals and the theory of generation, fhould therefore either be confuted or confirmed” (276-7). Although evolution was not yet a scientific theory when Mills was writing, we might say that mules and hinnies challenge the distinction between animals and the theory of evolution that divides animals into distinct and knowable species. If mules and hinnies aren’t species, what are they? If they exist in a subdivision below species, why are we looking at species? How do we know that species is the correct level to be looking at? Why not go higher or lower? How do we even know that the term species refers to a real group, especially as exceptions come to light? Mules and hinnies have the capacity to open up a whole host of uncomfortable questions just by existing.

I would say I’ve never ridden a mule or a hinny… but when I first came to the sanctuary I mistook the mules for horses, so what do I know?


Richards reflects on this train of thought by writing about the concern of realism; “because species play a theoretical role, functioning with scientific theories, they have theoretical significance. And this seems to require that they be real! If species are not real, so much the worse for all our biological theories that presuppose the reality of species. Furthermore, if species are not real, it is hard to see how we can preserve them, or why we should try. Surely we do not want to waste resources on the preservation of biological fictions” (11). The idea that putting money into preserving biological fictions is a waste relies on the presupposition that there are other, actually real, biological entities that better deserve our money. It’s not so much that species aren’t real and everything else is, but more of a question of, what does real mean, and is anything really real?

At the very least, there is a lot of money bound up in species being ‘real.’ Another reason that mules and hinnies have been overlooked is that they do not count as species. If we don’t want to waste resources on biological fictions, why would we waste resources on human inventions that don’t even count on the level of the basic unit of life?

In light of these considerations we might either:

  • i) argue mules and hinnies are species and scientists should change how they write about species to recognize this, or,
  • ii) argue mules and hinnies show that species is in fact a fiction that is being used to preserve and pay attention to certain, or ‘ideal,’ forms of life over others.

Here are some of those ideal forms of life that do fit into how we categorize them, in this case as Equus asinus. Aren’t they so cute and species conforming?


VII. Where do Humans Fit in?

Humans have long thought about mules and hinnies as animals well designed for our use. In 1707 Gent described mules by writing that they are “a beast commendable for Labour” (104). Similarly, in 1776, Mills wrote, “they feem born for carrying heavy burthens, for carrying them gently, and for lafting a long time” (277). Mules are frequently discussed by mentioning what they can do for humans and how they were ‘naturally’ capable of doing such work. What a coincidence, right?

“All male mules and most female mules are infertile, so their continued existence depends entirely on human intervention” (“11 Amazing Hybrid Animals”). Mules don’t exist without us. Recognizing the human hand in mule and hinny lives has a long, albeit largely invisible, history. In 1776 Mills wrote, “we know not of any wild ones” (277).

I used to ride at a stable that sent out an email to all of the riders about a horse that the owners had heard about. Something bad had happened to this horse and the owners wanted to adopt or save them. Saving the horse meant buying them from the horse’s current owners and so they were asking the riders for donations. I remember being very puzzled by this email. The stable already had at least 40 horses. Was someone going to ride this horse? What happened if they refused to be ridden? What happened when they got too old? Would the stable owners still be interested in saving the horse then? If they were, why was saving this one horse more important than all of the other horses that had previously been bought and sold at this stable? Why did this one, bound up in the same system where they were seen as an object, warrant human sympathy? Couldn’t the stable owners see that the very way that they were obtaining this horse, by buying them, was sustaining the same system that allowed something bad to happen to the horse in the first place?


Writing about mules and hinnies is also always writing a story as humans about a human in(ter)vention. While Donna Campbell speculates that mules were around prior to human intervention because horses and donkeys lived in close proximity (1), horses and donkeys only lived in close proximity because of human intervention. The earliest recognizable ancestor of horses and donkeys was around 54 million years ago (Chaline 72), but when we domesticated horses they were in Central Asia and donkeys were in the Middle East (Burnie and Wilson 226). Even if donkeys and horses did interbreed without human intervention of some form, arguably all of the mules and hinnies alive in the world today are the product of varying levels of human intervention. Even accidental mules and hinnies, born by donkeys and horses in the same paddock, are the product of humans domesticating their equine parents. Also, as I noted earlier in a discussion on gender, most mules and hinnies are the product of much more direct human involvement.

In my wandering through texts on mules and hinnies I try to sort out, where do humans, mules, hinnies, horses, and donkeys separate? The far more interesting question to keep in mind might be, what happens in this intermingling hybrid-multispecies space where they don’t?

Horses come and go a lot at riding stables. I’m not quite sure where they come from and where they go to, and I don’t think I’ll ever really find out anytime soon. I had been working at one particular stable for a little while when we acquired a new pony, bought because they were small enough for children to ride comfortably. To everyone’s surprise (I have no idea why I was surprised), this pony did not like children. Shortly after being purchased, we had to move the pony to a private barn so that they would stop trying to bite anyone that walked past their stall. Only experienced riders could ride the pony, because they bucked, and since many of us preferred tall, elegant, beautiful horses, the pony was barely ever ridden. They spent most of their time outside.

My first personal interaction with the pony was leading them from their stall to a pasture. Walking there was fine because I could walk backwards quickly, so that I never took my eye off the pony. With enough slack on the lead rope, the pony was rarely right beside me. Sometimes the pony would take advantage of this slack and shove me and we’d have a pushing contest all the way to the pasture. Luckily the pony was pretty close to my size so I never fell over or actually got hurt. In retrospect though, I now realize the pony must have just been playing around because they did weigh several hundred pounds heavier than me. After leading the pony to the pasture one of the biggest problems was the gate; there was no way to open it without taking your eye off of the pony and getting bitten. Sure enough, as soon as I turned around for the ten seconds required to open the gate, the pony was nipping at my arms. Then I had to open the gate, get the pony inside, and go in after the pony to take the lead rope off (but not the halter, because no one ever took that off, or you would never get it back on). Of course, that meant I was then stuck inside the pasture with the pony, now completely unrestrained. Eventually the pony would get bored and wander away, but until then I’d play chicken with the gate, trying to get out without letting the pony follow me (or bite me).

One day it was thundering and storming outside and I was told to bring the horses in. I had specifically been instructed to get the pony last. By the time I brought the pony in they were completely drenched and I was really worried that they would get sick. For the first time ever, I walked into the pony’s stall with a brush. The pony glanced up at me from eating and then proceeded to ignored me. They stood there calmly while I dried them off for over fifteen minutes. The following week I took the pony to the pasture just like I always did, except this time there were no bites or shoves. The pony didn’t bite or shove me ever again after that. I would still let the pony’s lead go loose when I’d lock doors and open gates, but now because I was unconcerned and could turn my back on the pony. I remember one time in particular when the pony’s lead was very slack and another rider came up behind me. The pony immediately lunged at them, letting me know very clearly that it wasn’t humans the pony now tolerated. It was just me. After that I always offered to take the pony out to the pasture.

Time passed and one day I came back to the stable and the pony was not there. Supposedly the pony had been sent to a ‘cowboy’ who would train the pony to be better at riding. After that we’d get the pony back, but they never did return. Telling the riders at the stable that horses ‘went to another farm’ was a frequent way to cover up when horses were euthanized or died, and so, I’ve always been haunted by what probably happened to my friend. After volunteering at the sanctuary, I’ve learned that ending up at a slaughterhouse is not off the table.


VIII. What do Mules and Hinnies do (for us)?

There are an estimated 275,000 mules in the United States today (Campbell 64), and an estimated 12.3 million mules living in ‘developing countries’ (Burn 109). It is likely that almost all of these mules and hinnies are owned by humans and are used for human means.

Some of the activities that mules and hinnies do for humans today are act as riding animals for both pleasure and competition, they are kept as exotic pets, bred to be show animals, used in farming, and give rides as tourist attractions (Campbell 23, 56, 58).

Mules and hinnies have been with us for approximately 3,000 years (Campbell 1) and have been used for many purposes since. Here are some of the ‘highlights,’ many of which are deeply interwoven in stories of human violence:

– in the Middle Ages mules were arranged in ‘trains’ and carried supplies where the terrain was too unsteady for horses and wagons. During the same time period they were also bred by upper class ladies for riding (Capmbell 2).

When riding any equine you use the reins to steer and pull them to slow down or stop. You press your feet into the equine’s side to get them to go or move faster. I used to know a horse that did not obey these signals. Sometimes the horse would jump up and down. Usually you could get them to stop by pushing with your feet, and urging them forward, but this didn’t always work, and what if you didn’t want to move? Pulling with your reins was discouraged. The horse didn’t like it and sometimes they actually sped up when you did so. There was no surefire to get the horse to stop, and yet, I was assigned to ride this horse a few times in jumping courses. During one of these occasions I was nearly thrown through a window. I guess that’s better than being almost thrown into a wall. Only one person actually liked riding this horse and they felt very attached to them, even though I’m sure that they fell off a few times. They had a special bond. One day, without notice, the horse was sold. I have no idea where the horse went and I don’t know what happened to them, but based on their disinterest in being ridden, I am not optimistic.


– Horses, donkeys, and likely mules, were brought to North America during European colonization in the fifteenth century and were used in warfare against the First Nations peoples living there (Chaline 72-3; Campbell 11). Prior to this, horses had been extinct in North America for the last 8,000 years (Chaline 77). Donkeys had never been to North America before.

– Mules only became common in North America after George Washington imported larger donkeys from Spain to breed larger mule offspring and when they were brought into the mines to replace horses, who were more nervous (74-5; Campbell 3). Manipulating the size of mules was so important that there was a law passed in France in 1689 that made it illegal to breed a male donkey with a female horse under fourteen hands, or fifty-six inches at the withers (Mills 279).

One of my favourite things about donkeys is that they do not have the same ‘spook’ response that horses do. When horses get scared, they run. This makes it extremely difficult to catch an escaped horse and can make for very dangerous riding – both of which I know from experience. I am pretty sure that a horse once threw me because they were startled, which resulted in my concussion. Donkeys do not scare quite the same way. Usually they will trot a few feet away, stop, turn around, and look at whatever startled them. I feel a lot safer around donkeys. While it’s always important to watch them, I am less worried about accidents. I have seen mules respond with both behaviours.


– Mules were considered ‘invaluable’ for Western expansion in North America because they were better than both horses and oxes on the terrain and could survive on a lot less food (Campbell 5).

– At specific points in history some humans were literally treated ‘as mules,’ as is referenced in the term mulatto, and mulatta, which is “usually the offspring of a Euro-American slave-owner and a slave woman,” and comes from the Portuguese word meaning ‘young mule’ (Young 21-2). In Mules and Dragons Mary E. Young considers the mulatta as one of several stereotypes that has been applied to African-American women. The term mulatto was first used in 1622 and like the mule itself, “mulatta is also a bearer of burdens, and some nineteenth-century racial zealots theorized that, like the mule, the mulatta was also sterile” (22). Many historical texts apply the verb ‘break’ when discussing how they would ‘train’ mulatta and mules to act in ways that were desired (Young 19; Mills 280; Goldsmith 283). Furthermore, both mules and Black slaves were forced to do labour during the day and some would also be forced to participate in racing (with the mule as horse and slave as jockey) for the entertainment of White mule and slave owners (Campbell 8).

– Mules have a long history as used in human warfare. Lucy Herndon Crockett wrote the novel Capitán in 1940, told from the perspective of the mule protagonist; Capitán was a mule used in WWI and is telling their story to the young mules after they have been branded with the letters I.C., for Inspected and Condemned (Crockett 2, 5). Because Capitán is “too old for service,” an officer from the army has said that Capitán must be ‘destroyed’ to stop wasting taxpayer’s money on oats (3, 301). Right before Capitán is about to be shot, they are saved by a letter from the postmaster, carrying news of the United States of America’s Act of Congress of 1939, which said that “horses and mules belonging to the United States which have become unfit for service may be destroyed or put out to pasture” (308, 312). The book ends with Capitán saying “it makes a mule feel that everything’s all right” (309), but everything is not all right. The Act still allows horses and mules to be ‘destroyed’ and did not save the many horses and mules killed between WWI ending and when the Act came out. Many mules in WWI and WWII were sold to slaughterhouses or put up for auction after the wars were over (Campbell 12, 14).

– Day’s 1916 book The Care of the Horse and the Mule and How the Harness Should Fit, written for soldiers in the army, includes a section on how to ‘humanely’ kill a horse. Like in Crockett’s fictional rendition, this involves shooting the fully conscious equine in the head with a gun (Crockett 307; Day 36). Day does not tell the reader why we need to know how to kill a horse or mule humanely, but the “the horse’s prayer” at the end of the book gives us a clue.

Here are several excerpts from the prayer:

“To thee, My Master, I offer my prayer: Feed me, water and care for me, and, when the day’s work is done, provide me with shelter, a clean, dry bed and a stall wide enough for me to lie down in comfort…

Always be kind to me. Talk to me. Your voice often means as much to me as the reins. Pet me sometimes, that I may serve you the more gladly and learn to love you. Do not jerk the reins, and do not whip me when going up hill. Never strike, beat or kick me when I do not understand you…

Remember that I must be ready at any moment to lose my life in your service…

And finally, O My Master, when my useful strength is gone, do not turn me out to starve or sell me to some cruel owner, to be slowly tortured and starved to death; but do Thou, My Master, take my life in the kindest way, and your God will reward you here and hereafter.” (Day 43-4).

Twice when I was riding I made a big mistake and lost hold of my reins. One time, over a jump, I also lost my stirrups. This left me with no way to ask the horse to stop and a very difficult time staying in the saddle, especially because the horses were cantering at the time. One of them was also bucking. I lost my balance and both times fell on the horse’s neck. Immediately those horses stopped cantering and went to a full stand still. I grabbed the reins, sat back up, and everything was okay. I still vividly recall how, after stopping, those horses turned their heads around and looked at me. I’m not sure if they were checking to see that I was fine or if they were trying to figure out what ridiculous thing I was doing. I had ridden both of these horses at least a dozen times before and was very well acquainted with them. I’d like to think that they stopped to make sure I was okay because they knew me and genuinely cared, but maybe they were just nice horses. One of them actually seemed to like being ridden and would buck and make a fuss when we just cantered around without doing any jumping courses. They seemed to get a thrill out of the jumps and I felt very safe with them. This horse was such an experienced jumper that the first time I was doing doubles, a jump with two poles where the horse has to take a long leap, forcing you to stay in the air for twice as long, they corrected their position in midair to adjust for my own sloppy position. Sometimes I wonder what happened to those horses. Are they still at the stable? Were they sold? Are they alive? Will someone still pay for them to be alive when they can no longer jump? Sometimes I think about how when I have a steady income I could buy them and they could live out the rest of their lives with me, just hanging out, but then aren’t I just paying for another horse to replace them? Sometimes I know I’m running out of time, I’m probably already too late, maybe they’re already dead, and the whole thing is just a mess. I can’t think of a happy way that their stories will end and I feel responsible. I wish I could say sorry, but who would I be doing it for?


IX. What do we do to Mules and Hinnies?

In my wandering through scholarly databases I came across eight academic articles on mules and hinnies and would like to conclude with them as a case study that makes explicit the vast differences in how we treat mules and hinnies, what our society considers legal and legitimate to do to mules and hinnies, and for what purposes such acts are done. The studies are arranged in chronological order and in each section I discuss why the study was done, what did we learn from the study, and what was done to hinnies and mules in the study to obtain this information.


I) Malmheden, Yman, Ingrid and Kaj Sandberg. “Differentiation of Meat from Horse, Donkey and Their Hybrics (Mule/Hinny) by Electrophoretic Separation of Albumin.” Meat Science 21.1 (1987): 15-23.

why was the study done: to be able to distinguish between donkey, horse, hinny, and mule meat. This was important to the authors because horse meat was being declared in Sweden illegally as donkey or mule meat to avoid customs (21).

what did we learn: This study determined that horses, donkeys, hinnies, and mules can only be distinguished by looking at serum albumin (22).

what was done to hinnies and mules in the study to obtain this information: they were killed; the meat was obtained from slaughterhouses (16).

II) Camillo, F., I. Vanozzi, A. Rota, B. Di Luzio, S. Romagnoli, G. Aria, and W.R. Allen. “Successful Non-Surgical Transfer of Horse Embryos to Mule Recipients.” Reproduction in Domestic Animals 38.5 (2003): 380-5.

why was the study done: to “obtain pregnancies and live foals following non-surgical transfer of horse embryos to mule recipients” (380).

what did we learn: “this study demonstrated that it is possible to obtain pregnancies and live foals after non-surgical transfer of horse embryos to cycling mules” (382).

what was done to hinnies and mules in the study to obtain this information: they “mated” mules who were “used as embryo recipients.” “The donor mares were inseminated on the day after hCG administration and, if necessary, every second day thereafter until ovulation occurred” (380). Embryos were removed from their original mothers and put into a mule “using a guarded French embryo transfer gun.” Three embryos did not survive the process of being moved. “Jugular vein blood samples were collected 1–3 times per week from the two recipient mules that became pregnant.” “Three embryos were transferred, on two different occasions, to the non-cycling mule but none resulted in a pregnancy” (381). “Our non-cycling mule treated with oestrogen and progesterone before transfer failed to became pregnant, despite being used twice as a recipient” (382).

III) Guo, Shuangping, Jianrong Lu, Heng Li, Jing Ye, Fucheng Ma, Yangmei Wang, Qang Li, and Feng Zhang. “Mule or Hinny Might be a Natural Model for Studying the Role of Parent Genomes in Carcinogenesis.” Medical Hypotheses 71.5 (2008): 810-1.

what did we learn: the role of paternal or maternal genomes play in causing cancer is unclear. They write, “we propose that mule (jack donkey · mare) or hinny (stallion · jenny donkey) might be a natural case for testing the hypothesis” (810).

what was done to hinnies and mules in the study to obtain this information: a study was proposed and no information was offered as to how the mules and hinnies would be treated. It appears quite evident that they will be given cancer.

IV) Proops, Leanne, Faith Burden, and Britta Osthaus. “Mule Cognition: A Case of Hybrid Vigour?” Animal Cognition 12 (2009): 75-84.

why was the study done: It is well known that mules have enhanced physical capacities compared to donkeys and horses and they proposed testing the cognitive capabilities of mules and hinnies to see if their hybrid vigour also extended to their minds (76).

what did we learn: “mules outperformed both ponies and donkeys in the visual discrimination task” (81).

what was done to hinnies and mules in the study to obtain this information: all of the animals used in the study lived at a donkey sanctuary. “The subjects were not food deprived for the experiments and were brought to the test area from the field or indoor barn when required.” “Only animals that were accustomed to feeding from buckets and showed no separation anxiety when brought to the test area were included in the study” (77).

V) Burn, Charlotte C., Tania L. Dennison, and Helen R. Whay. “Relationships Between Behaviour and Health in Working Horses, Donkeys, and Mules in Developing Countries.” Applied Animal Behaviour Science 126.3-4 (2010): 109-18.

why was the study done: to study the animal welfare of animals, including mules, in ‘developing countries’ to see if their responses could be connected to their physical conditions (110).

what did we learn: “behavioural unresponsiveness correlated across the behavioural measures in the current study, and was associated with more numerous or severe physical conditions” (117).

what was done to hinnies and mules in the study to obtain this information: the animals were observed in their every day environments as working animals owned by humans, approached at normal pace, approached at an angle of 20 degrees, the experimenter walked towards their rear, and touched their chin (111).

VI) Paolucci, M., C. Palombi, L. Sylla, G. Stradaioli, and M. Monaci. “Ultrasonographic Features of the Mule Embryo, Fetus, and Fetal-Placental Unit.” Theriogenology 77.2 (2012): 240-52.

why was the study done: “the objectives of the present study were to further validate the ultrasound assessment of equine fetal-placental well-being by using it throughout pregnancy and to establish reference guidelines for different gestational stages for an interspecies pregnancy, as the main reports have generally focused on equine gestation” (241).

what did we learn: “we can assume that early diagnosis of pregnancy failure and assessment of fetal biophysical profile and growth charts could improve the chances of gestation completion in mule-pregnant mares. The early detection of mares at risk for an abnormal pregnancy or delivery may increase the success of prompt treatments during gestation, therefore preventing costly emergency procedures and allowing proper obstetrical and neonatal assistance” (250).

what was done to hinnies and mules in the study to obtain this information: the study was done at a teaching farm where twenty-eight mules were impregnated over five years (241).

VII) Proops, Leanne, Faith Burden, and Britta Osthaus. “Social Relations in Mixed Groups of Mules, Ponies and Donkeys Reflect Differences in Equid Type.” Behavioural Processes 90.3 (2012): 337-42.

why was the study done: “recorded affiliative, dominant and submissive behaviours in a mixed group of 16 donkeys, mules and ponies in order to assess whether dominance rank, linearity of dominance structure and choice of preferred associates could be determined by equid type” to better understand the social behaviour of mules (338).

what did we learn: “The animals clearly distinguished one another based on equid type and although subgroups of preferred associates were based in part on rank, the main determinate was equid type.” (341)

what was done to hinnies and mules in the study to obtain this information: the study was done at a donkey sanctuary. Every 15 minutes the researchers recorded where the donkeys, mules, and horses were standing (339).

VIII) Grint, Nicola J., Craig B. Johnson, Silvia De Sa Lorena, Stelio Luna, Carlos A. Hussni, Helen R. Whay, and Joanna C. Murrell. “Electroencephalographic Responses to a Noxious Surgical Stimulus in Mules, Horses, and Ponies.” Journal of Equine Veterinary Science 34.8 (2014): 955-62.

why was the study done: to “repeat the “minimal anesthesia” method [5] in a group of different equidae; horses (Equus caballus) and mules (Equus asinus x Equus caballus) to compare the species’ response to a noxious surgical stimulus” (956).

what did we learn: A previous study on anesthesia and surgical protocol was confirmed and a disparity in EEG data collected from the cerebral hemispheres was noted and it had not previously been reported in equines before (961)

what was done to hinnies and mules in the study to obtain this information: they used equines that had previously been ‘unhandled’ and so they could only do a brief clinical examination. They anesthetized the equines. “Animals were starved of food but not water overnight before general anesthesia. After skin infiltration with lidocaine (Xylocaina; Astrazeneca, Sao Paulo, Brazil), a 14-gauge catheter was placed percutaneously in the jugular vein and secured in place” (956).


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Page last edited December 16, 2014. N.T. Rowan can be contacted at [email protected]