It shouldn’t come as a surprise that, as humans, we tend to think like humans and form our decisions based on our opinions and preferences as such. There are some inter-species universal truths where this tendency will serve us well with our horses; but in some instances our human instincts will mislead us to make decisions for our animals that are not in their best interest. One such instance where our human minds lead us to unfortunate decisions with our horses is with bits and bitting.
When I’m working with new students who are unfamiliar with the tools used to communicate with our equine partner, inevitably I see a grimace when I explain the bridle for the first time. “You mean, that metal thing goes in their MOUTH?!” they will exclaim with incredulity, and you can see these inexperienced riders imagining a big metal bar in their own mouths as they wince with sympathy for the “poor horse” upon whom they will soon be inflicting this horror.
While the reaction from more seasoned riders is more tempered than that of the initial realization of where a bit goes and how it works, there are still those out there with many years of riding under their belts who think in more or less this same way—I wouldn’t want to carry a piece of metal in my mouth, so why should I ask my horse to do it?
While a person’s hesitation to put metal in his or her horse’s mouth isn’t in and of itself harmful to his or her equine partner, the subsequent selection of headgear used in order to ride the animal without the “offensive” piece of tack may very well cause inadvertent harm, even with the rider’s best of intentions.
It is for this reason that I find myself needing to explain time and again how bits work, why they are not a problem for horses the way they would be to a human, and how to properly gauge the severity of any given bit or bitting system. Armed with this knowledge, people are more equipped to make a decision on their horse’s headgear that is not only effective but also beneficial to the horse rather than being misled by their faulty human intuition.
First of all, I would like to address one of the most common oppositions that people have to bits, which is when we think about carrying around a piece of metal in our own mouth how uncomfortable and problematic it would be. This is because, as omnivores, we humans have teeth pretty much the whole length of our gum-line. There exists no good place to comfortably hold a bar of metal without it interfering with our teeth! Horses, on the other hand, have a long section of gum-line without teeth because they lack the canine teeth used by omnivores and carnivores to rip into flesh. This section of tooth-free gum-line is called the “bars” of the horse’s mouth, and makes a very comfortable place to carry a bit.
Next lets talk about how to judge the severity of a bit. Try this little quiz. Observe the following bits. First, identify what kind of bit each one is and then put them in order from least to most severe. If possible, say why you rated them the way you did.






The bits are as follows: 1. D-ring snaffle 2. Tom-thumb (curb) 3. Curb with a jointed mouth-piece 4. Plain smooth curb with a port 5. Elevator bit (has action of both curb and snaffle) 6. Mechanical hackamore.
To rate these bits from the most to the least severe, there are various factors to take into consideration. In general, the larger diameter mouthpieces are milder than thinner ones, and curb bits are more severe than snaffle bits.
The defining characteristic of a curb bit is its shank—the arm-like extension from the mouthpiece to which the reins attach—which gives the bit an element of leverage (in fact, they are sometimes referred to as “leverage bits”). Leverage is precisely what makes a curb more sever than a non-leverage (snaffle) bit.
What leverage does—whether in a bit or a hackamore—is it intensifies the pressure exerted by the rider on the horse, meaning if you apply three pounds of pressure, the horse may feel five, 10, or even more depending on the severity of the leverage. The amount of leverage is in part determined by the length of the shank. The longer the shank, the more severe the leverage. Additionally, leverage (curb) bits always apply pressure to at least three areas on the horse: the mouth, under the chin (through the curb chain), and over the pole (through the headstall).
In contrast, a snaffle bit is designed so that the mouthpiece and the reins attach at the same location and will only exert pressure on the mouth of the horse. The horse and the human will perceive this pressure identically, meaning if the rider applies four pounds of pressure, the horse feels exactly four pounds of pressure. Whether this pressure is mostly perceived on the bars, tongue, or the roof of the mouth is determined by the shape of the mouthpiece and the number of joints in it. In general, a snaffle bit with more joints is milder than one with only one joint because more joints mean that the pressure applied by the rider is distributed over a larger area within the horse’s mouth simultaneously.
Keep in mind that curb bits can also be jointed. Many people mistakenly assume that any bit with a jointed mouthpiece is a snaffle bit, but this is a dangerous assumption because a jointed curb bit can be just as severe or more so than its smooth counterpart. A mouthpiece has nothing to do with a bit’s classification as a curb or a snaffle; rather, if a bit has leverage, it’s a curb bit.
If you chose number six, the mechanical hackamore, as the most severe you chose correctly. This comes as a surprise to many people, since it is the only “bit” that does not even go in the horse’s mouth. I have seen many well-intentioned riders who choose a mechanical hackamore for their horse thinking that it is a “kinder” option than putting metal in its mouth, not realizing that they are not doing their horse any favors with this very severe bitless bit. Horses ridden for extended periods of time in a mechanical hackamore will almost always present some scarring either over the nose or under the jaw, as well as a few tell-tale behavioral tics they pick up as a defense mechanism against the discomfort they can experience while wearing one, especially if this harsh tool is employed as a substitute for good training or used by unsteady hands.
A mechanical hackamore is distinct from other, more traditional types of hackamores such as the bosal and the side-pull due to its leverage ability and nutcracker-like action on the horse’s head. The mechanical hackamore’s action works in three ways: over the bridge of the horse’s nose, under his chin (from the curb chain), and downward on his pole (from the headstall of the bridle). When the rider activates the reins, the whole headpiece contracts, exerting pressure on these three spots simultaneously. Because of the leverage, this pressure is perceived by the horse much more intensely than what the rider thinks he or she is administering. This is what puts this bitless bit at the top of the list for the most severe.
The next most severe bit on the list would likely be number three, depending on how tightly adjusted the curb chain would be. The reason for this is again that it has the longest shanks of the bits represented and therefore the most leverage.
Both number two and number three are often mistakenly referred to as snaffle bits because of their jointed mouthpiece. In fact, number two is commonly referred to as a “Tom thumb snaffle”. But remember that a jointed mouthpiece has nothing to do with a whether or not a bit is classified as a curb. Since they both have a shank, they are both curb bits.
The next most severe would be probably either number two or number four due to them having more or less the same length of shank and therefore similar intensity of leverage. Which one would come first in terms of severity would depend on how tightly the curb chain is adjusted. Assuming all other factors are equal, the tighter the curb chain, the more severe the bit.
Number five would be second to last on the list of most severe because it can be used as either a snaffle or a curb bit, depending on where the rider attaches the reins. If you attach the reins directly to the ring where the mouthpiece is attached, then you are riding in a snaffle; if you attach it to the end of the shank, you are riding in a mild curb. Even attaching the reins to the shank, though, this bit still sits at the bottom of the list of severity compared to the other curb bits represented here because the shank is so short that it exerts very little leverage. Additionally, the “gag” action (the ability of the mouthpiece to slide on the rings) alleviates some of the pressure on the horse’s mouth, which makes this bit a fairly mild option either as a curb or a snaffle.
Bit number one—the d-ring snaffle—is the mildest bit in the series. This bit has no leverage so the rider feels the same pressure that the horse does, and the diameter of the bit is large enough distribute the pressure well. A snaffle bit requires no curb chain, so there is no squeezing action under the horse’s jaw when the rider applies the rein aid. This simple bit is usually well-received by most horses, and is, in my opinion, one of the kinder ways to communicate to a horse under saddle.
A true fact of bits is that a bit is only as harsh as the hands on the other side of it. That being said, there are very few appropriate uses of the harsher bits, especially by green or unsteady riders or on under-trained horses. If a rider has trouble slowing or stopping a horse, the answer to not to resort to a harsher bit but rather to seek out more training for himself and his horse.
Of course, any questions you have about bitting or training, be sure to refer to a trusted trainer or instructor for help finding an appropriate mouthpiece for your horse.