Why Does My Horse Pee on Hay?

You give your horse a fresh, clean stall or paddock and a pile of tasty hay. And then your horse chooses to pee right on that hay. It’s a waste of your hay, time, and money. So what’s going on? Why do horses urinate on hay, and how can you prevent this wasteful and irritating habit? Here’s why horses pee on hay and what you can do about it. 

The Wrong Reasons Your Horse Pees on Hay

Why does my horse pee on their hay? Are they trying to get under my skin?  If you have a horse who preferentially or compulsively urinates on hay, that’s a valid question.  Is your horse sending you a message by peeing on their food? 

Good news: as frustrating and obnoxious as this behavior is, you don’t have to take it personally. When horses urinate on their hay, there’s usually a good reason. 

Let’s start by debunking some incorrect ideas to find the true, actionable reasons underneath.

1. Your horse pees on their hay for revenge. 

Does your horse pee on their hay to get back at you for something you did, or an experience they didn’t like? 

If you sometimes have an up-and-down relationship with your horse, you might wonder if your horse pees on their hay for revenge. Horses often urinate first thing after being returned to their stall or paddock after a ride or training session. If you asked them to work hard or had to correct their behavior, it’s logical to wonder if your horse pees on their hay as a form of revenge. After all, soiled hay is a waste of time and money, and can definitely make you angry.

The truth?  Maybe cartoon horses could act like this, but real ones don’t. Your horse doesn’t understand the idea of “taking revenge” the way people do. Even if your relationship isn’t the greatest, your horse does not pee on their hay to get back at you. 

2. Your horse pees on their hay to spite you and create more work.

You work hard and sweat over your horse’s care. Will a horse pee on their hay because they know you’ll have to do more work on their behalf? Do they get a kick out of watching you replace their hay and bedding?

Fellow equestrians might float this idea, but thankfully this isn’t a reason that horses pee on hay. Horse are intelligent, but their minds don’t understand the idea that peeing on edible hay means you spend more money or time on them. 

3. Your horse pees on hay to show that they don’t like their food.

You’ve probably heard this one before. Will a horse pee on hay as a statement that the hay wasn’t good enough for them? 

Your little brother might think this way, but horses don’t. 

It may be true that a horse may be more likely to urinate on hay that wasn’t especially tasty or was already soiled. But a horse with this behavior will also pee on fresh, high quality hay. If that same hay were in a feeder or net, they would happily eat it.  

These incorrect explanations are based on false ideas about how horses think. So what about a reason that comes from biology?

4. Your horse pees on hay to scent mark. 

This idea makes sense, especially if you own a stallion or even a gelding. Does your horse scent mark by urinating on hay?

Some animals do scent mark using urine. And scent is very important to horses: enrichment activities involving scent can be a great way to give your horse more sensory stimulation. 

But while stallions will create scented “stud piles” by defecating and urinating in a single area, they don’t mark by dropping urine around a territory the way a cat or dog does. And most geldings and mares display little to no manure “marking” behavior. 

So when your horse pees on hay, marking their territory is almost certainly not the cause of the behavior. 

So what’s really going on?

The Real Reasons Why Horses Pee on Hay

When horses urinate on hay, they’re using their forage as the equine version of toilet paper.

Seems nuts, right? Your horse has an entire stall of clean bedding. Or they’re a whole pasture full of places to have a wee. Why ruin their pile of food by peeing on the hay? 

Horses learn to pee on hay because they don’t want to be splashed with urine, and hay is very good at preventing pee from splashing up and around your horse’s hooves and legs. 

Staying Clean

Most horses have an innate dislike of urine splash. And you probably do, too!  Peeing in a paddock or stall often leads to an uncomfortable sprinkling of pee on your horse’s legs. and belly 

Horses may not seem like especially clean animals. They love to roll in the dirt and mud, and they don’t wash themselves or groom like a cat. 

But horses are actually very good at self-maintenance and keeping themselves clean, when they have the opportunity. Avoiding contact with bodily waste is instinctive in many animals, for good reason. 

Why Horses Don’t Like Pee Splash

Fresh urine is fairly clean, but no one wants to swim in it. For horses, too much exposure to urine can irritate the skin. And urine is strongly scented. For a prey animal like a horse, being soiled with urine is like turning on a scented beacon to predators in the area. Your domesticated horse is perfectly safe in their stall and paddock, but they still have the instincts and behaviors of their wild ancestors. 

So horses do not want to get splashed by their own pee. They’re also intelligent enough to understand that peeing in some places gets them splashed, while other surfaces absorb the urine and keep it off their skin.

This is why horses often choose a brushier or weedy area of the pasture to urinate, if one is available. But when there aren’t many options, the only place for them to go might be their hay pile. 

Your horse’s mind isn’t wired to realize that if they pee on the hay now, it will be soiled and inedible later. They’re simply seeking a solution to a problem. 

Horse Urine Vs Stall Bedding

My stalls have plenty of bedding. Why does my horse pee on their hay? 

It takes a lot of shavings or sawdust to consistently absorb your horse’s urine and prevent splash. 

It might seem like there’s plenty of fluffy, absorbent stall bedding. But when considering why your horse pees on their hay, think about the amounts involved. Horses are big animals, and each urination can be several liters in volume. That’s as much as a big soda bottle, all at one time and in a small area.

That amount of liquid will splash, especially if the bedding is already wet. Many horses simply don’t have deep enough bedding to prevent it. If they’re sensitive to urine splash, it’s understandable for them to find a more protective option: their pile of hay. 

The same is true in paddocks. Thick, dense grass absorbs the urine stream very well, but shorter pasture or a dry lot produces splash. Hard ground or muddy, saturated soil will also deflect the urine.

Keeping the Bed Clean

If your horse pees on their hay, they could also be showing an aversion to sleeping in their own urine. And just as with pee splash: who wouldn’t?  

This is most commonly seen in stalls. Pastures and paddocks create more possible locations for rest, so if your horse pees on hay during turnout, avoiding splash is probably the cause. 

In a stall, though, there may not be enough space for a horse to urinate and pee in different places. 

Understandably, some horses find sleeping on damp ground unpleasant. Ammonia gas, produced by pee after the horse urinates, is also very strongly scented. It can damage the lungs, or be overwhelming to your horse’s sensitive nose. 

Over time, your horse may learn that peeing on the hay pile before sleeping on the stall floor produces a more comfortable night’s sleep. 

Peeing On Hay is a Long Term Habit

Horses are good learners and have long memories. If your horse has been stalled on thin bedding in the past, they may have learned that the center of the stall isn’t a great place to pee. Even if you change the type or amount of stall bedding, they may be very hesitant to start urinating there in the future. 

The same is true if your horse urinates on hay to avoid sleeping in pee. Over time, they’ve been trained to pee on their hay, and switching to a bigger stall may not automatically solve the problem. 

Preventing Horses from Peeing on Hay

So how can you effectively and humanely stop your horse from peeing on their hay? 

The good news is that by knowing why your horse urinates on hay, you can develop a plan to get their pee habits back on track. You’ll both be happier in the long run! 

But it’s important to be compassionate – even though urinating on hay is frustrating – in your strategies and approach. After all, everyone pees regularly, and there will probably be some mistakes during the process. 

Beyond simply adding better bedding to your horse’s stall, there are some things to keep in mind as you reteach good equine toileting. For the best chance of success, find details in the full article on what to do when your horse pees on hay, found here.