Hay Belly in Horses

Three Welsh mountain ponies (Equus caballus) in a field, including chestnut coloured pregnant mare and foal, and grey pony
Bob Langrish / Getty Images

If your gelding suddenly appears pregnant (although not physically possible), he may be suffering from hay belly. Don’t be embarrassed—your horse hasn't gained the "Freshman 15." But he could have a nutritional imbalance from grazing on too many grasses. And while a severely distended abdomen looks alarming on a horse, balancing out its diet will get it back on track. Over time, the hay belly will deflate and your horse will, again, be growing at its normal clip. But if left untreated, hay belly could cause loss of muscle mass and leave your horse lame.

What Is Hay Belly?

The term "hay belly" refers to a distended abdomen on a horse. The belly area appears pendulous, sticking out on the sides and hanging down low. Hay belly often makes a horse look underweight, with protruding ribs and a lack of padding and muscles on the neck, shoulders, and haunches.

Symptoms of Hay Belly in Horses

Colic symptoms like restlessness, sweating, or excessive stretching may be present in a horse with hay belly. A horse may also develop a lackluster coat and may appear to be in poor condition. However, this isn’t always the case. Hay belly can occur in horses of any age, so if you notice a degraded appearance of your once-vibrant horse, contact your veterinarian for a correct diagnosis. A distended abdomen can also be a product of parasitic infection.

Causes of Hay Belly

Some horse owners think that hay belly is caused by poor nutrition. However, it's not quite that simple. Specifically—a nutritionally-inadequate forage can cause a horse to eat more to make up the shortfall. This large amount of fodder has no way of breaking itself down, so the gut's naturally-occurring bacteria go at it, causing fermentation. With fermentation comes the creation of gas in the stomach, causing the belly to expand. That's why some horses with this condition will appear visibly larger just after a meal.


If you suspect your horse has hay belly, consult your veterinarian for advice on a high-quality diet protocol. If your horse is left on pasture, your vet may suggest supplementing its grazing with nutrient-dense hay and may suggest a protein supplement to offset the nutrient loss from eating too many grasses. Or, you may simply need to change up your horse's hay altogether, sourcing a more reputable grower and changing to a higher quality forage.

After a few weeks of feeding protein-rich feed and supplements, you should notice your horse's belly starting to retract. Muscle mass will again begin to develop, and your horse's coat will return to its glossy norm. Maintaining a quality diet, especially in the winter when snow is on the ground, is the key to keeping your horse in sound condition. Make sure to communicate your progress with your vet to assure you're on the right track.

When It's Not Hay Belly

Not all big bellies are hay belly. A horse's distended abdomen could be attributed to Cushing’s Disease or liver failure. Horses who crib bite (a behavioral disorder) often have distended abdomens related to colic or stomach ulcers. And a horse that looks unhealthy, yet has a large belly, may have a severe parasite load causing bloating and inflammation. Lastly, mares who have mothered several foals, as well as older horses, may appear to have a hay belly due to a stretched slackness of the muscles in the back meant to support the stomach.

Pay special attention to foals with a large tummy. If the foal is in poor health overall, parasite control may be needed. Also, foals need carefully balanced nutrition throughout their growing stages. But don't overfeed them, as this can cause other health problems.

How to Prevent Hay Belly

Proper nutrition is the first step to maintaining the health of your horse. Always feed your horse top-quality hay and learn how to identify it before purchase. Remember, even if your pasture appears green and flourishing, your grass may not meet your horse's needs once dry weather sets in and environmental conditions change. And while horses spend the bulk of their time grazing, a balanced supplement or concentrate may be given to assure they're getting the vitamins, minerals, proteins, and carbohydrates they need.

Regular exercise also helps prevents the appearance of a sagging torso. When a horse is physically fit, the muscles surrounding the belly are well toned. This is especially important in broodmares and older horses. A break from motherhood and regular riding helps build the muscles that support the stomach while contributing to proper digestion and healthy joints.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.