I didn't get my first horse until I was in my 30s (circa 1981), so I had a lot to learn back then. One of the things I learned early on in my horse experience was what a hay belly is on a horse and what to do about it if it develops.
So, what IS a hay belly? "Hay belly" is often a junk term used to describe a horse with a distended gut. What's causing the distension in the horse's belly is more a cause for concern than the actual look of it. Always be sure to properly worm your horse – a horse with worms will have a distended gut, but this is NOT hay belly!
My equine vet here in Brainerd, Dr. Greg Harms, explains the various "meanings" of hay belly:
"Hay belly" is a layman's term that can mean different things to different people.Firstly, it's most commonly associated with feeding a poor quality or low protein forage with no grain supplement. This causes the distention of the abdomen because of increased volume of feed stuffs and decreased musculature from low protein.Some people will also give multiparous mares this adjective because of their pendulous abdomen.And finally, some young horses that are heavily parasitized and/or poorly fed will get this moniker.
A real hay belly – the one we're talking about here – is the distended gut the horse gets due to the poor quality feed it's eating.
What Causes Hay Belly in a Horse?
Okay, so a hay belly is caused by the horse's food...but what actually causes the belly to distend?
Unfortunately, some horse people think "hay belly" means the horse is eating too much hay. That's not the case at all.
The culprit of hay belly is poor quality hay or grass. Horses – like any animal – need the proper amount of nutrients in order to maintain their weight and health. Horses' digestive systems are built to effectively extract nutrients from "roughage" (hay and grass). Since horses don't have their own way to break down fiber, they rely on bacteria in their large intestine (the hindgut) to ferment the hay/grass. Low quality hay or grass will remain in the hindgut for longer periods of time, causing the bacteria to work overtime trying to extract any nutrients it can...this causes extra fermentation, which in turn distends the belly. Read: hay belly!
Does My Horse Have Hay Belly, or is He Fat?
Again, sadly a lot of horse people think their horses are fat because of their swollen bellies, when in fact the horses are suffering from poor quality forage.
How do you tell the difference between a horse being fat and a horse with a hay belly? Simple. Poor quality hay (or grass) doesn't have enough protein in it. Horses use protein to maintain (or build) muscle. So, if your horse has a big belly and has little muscle mass, your horse is suffering from poor quality forage.
The equine veterinarian my daughter uses, Dr. Donna Rued, weighed in on how to spot a hay belly:
Hay belly is when a horse bloats from eating a lot of low quality hay with not enough protein. If they're not getting enough, their muscles will show it – they'll either have little muscle mass or will be losing muscle due to lack of protein in their diet.
A healthy horse should never lose muscle mass – even when not being ridden for extended periods of time. If your horse has a big belly but is losing muscle mass, you need to do a few things:
- Get better quality hay.
- If your horse is on pasture, you need to supplement with good quality hay.
- Provide your horse with a protein supplement – i.e., grain.
My Horse is on a Round Bale, Why Should I Worry About Hay Belly?
Just because your horse has 24/7 access to hay doesn't mean it can't suffer from hay belly. Again, it's poor quality hay (or pasture) that causes hay belly; not the quantity the horse gets.
Case in point: my daughter's horse this past winter. She moved him from our house (free-choice, good quality round bale; no grain and in excellent condition) last fall to a stable down in the Cities. For the last couple months this late winter/early spring he'd been on a round bale and was receiving grain (oats + Safe Choice + Empower Boost)...yet he was losing muscle mass (and weight) and she was beginning to see his ribs, even though his belly was "big." She knew all he had was a hay belly...and that it was time to remedy the situation (the barn owners thought everything was fine and that it was normal for horses to lose weight in winter).
After moving her gelding to her vet's stable (where she was told he would be weaned onto a high-quality hay so he could gain weight by getting much-needed protein) she noticed a drop in the horse's hay belly and a return of his muscle mass (within 10 days). She no longer needs to feed him a fat supplement; he receives Safe Choice pellets once a day and good quality hay several times a day. And doesn't have a hay belly anymore.
So, just because a horse is on a round bale and getting grain doesn't mean the horse is fine. Make sure your hay (or pasture grass) is good quality – if you're in doubt, you can even take the hay to get its contents tested.
Hopefully it doesn't get to that point – mistaking a hay belly for a fat horse is a rookie mistake (one I made early on in my horse years, I'll admit!).
Some online resources about hay belly, nutrition, et.al.:
- Is It Fat...or Is It Hay Belly?
- Horses - Diet & Nutrition
- Hay Belly vs Fat
- Can Hay Belly Cause Ribby Look?
- Feeding Horses Hay Free Choice
- Basic Understanding of the Horse Digestive System
- Is Your Boarding Stable Killing Your Horse?
- Will Feeding Too Much Hay Make My Horse Fat?
When in doubt, the most important diagnosis of whether or not your horse has a hay belly needs to come from your equine vet.