Distended Abdomens or Hay Bellies in Horses

Three Welsh mountain ponies (Equus caballus) in a field, including chestnut coloured pregnant mare and foal, and grey pony
Mares that have had several foals can have what appears to be distended abdomens. Bob Langrish / Getty Images

Are you being teased because your horse has a big belly? Does your gelding appear to be in foal, perhaps with twins? Your horse may have a hay belly, and it doesn’t necessarily mean it is fat or suffering terribly from malnutrition. Don’t be embarrassed. Hay belly may take a bit of time to deflate, but it can be done. Here’s what causes hay bellies and what you can do about it.

What is a Hay Belly?

A hay belly is a distended abdomen. The belly area appears pendulous, sticking out to the sides and hanging down.  Horses that are underweight, rather than overweight can have hay bellies. Often, the horse’s ribs can be seen, and there’s little body fat padding the other areas like neck, shoulders and haunches. A hay belly is not fat. Sometimes the horse may have poor a poor coat and generally appear in poor condition. However, this isn’t always the case. Often, the horse’s overall health is fine. Older horses are more likely to develop a hay belly than younger ones. Foals too can appear to have a hay belly.

What Causes Hay Belly?

Some owners think that hay bellies are caused by poor nutrition or hay that is too low or high in fiber. This may not be the case. Any forage that isn’t nutritionally adequate may cause the horse to eat more to make up the shortfall. A large amount of fodder digesting in the hindgut --not necessarily hay, producing lots of fermentation (gas) causes the belly to appear large. Some horses will appear visibly larger after a meal.

Other Reasons for Big Bellies

Not all big bellies are hay bellies, however. A hay belly tends to be sagging and the lower part of the belly is distended. Bloating due to gas will be higher and further towards the horse’s flank. There is usually some colic symptoms with this type of bloating.

A distended belly can be a symptom of Cushing’s Disease and liver failure. Cribbers often have distended bellies. This is because of how the muscles develop when the horse cribs.

A horse that is both unhealthy, and has a large belly may have a severe parasite load. The distention is caused by the damage and inflammation caused by parasites. Mares that have had a few foals may appear to have a hay belly. This is due to stretched and slack muscles. Older horses may have the same appearance caused by weakening muscles. Often, horses with hay bellies may not be getting enough protein, which contributes to lack of muscle tone.

Foals may appear to have a hay belly. If the foal is in poor health overall, parasite control may be needed. Foals also need balanced nutrition. Care needs to be taken not to over-feed foals though, as this too can cause health problems beyond just being overweight. Parasite load will quickly appear as a bloated belly in a foal.

How Do You Prevent a Hay Belly?

Your horse should be fed top quality hay, so it doesn’t have to eat large quantities to make up its nutritional needs. Learn how to identify good-quality hay for your horse.  If your horse is only on pasture grass, you may need to supplement with good-quality hay. Your pastures may appear green, but your grass may not have all the nutrition your horse needs, after dry weather or in the fall.  Horses do need to spend a lot of time grazing, but they also need to be getting the vitamins, minerals, proteins and carbohydrates for good health. Some horses will benefit from a balancing supplement or concentrate to make up for any shortfalls in their hay and pasture.

When a horse is physically fit, it's less likely to have a hay belly, because all the muscles are well toned. Your horse also needs a regular parasite control program.

If your horse was or is a broodmare, there may be little you can do to totally regain your mare’s girlish figure. A break from motherhood and regular riding, especially schooling that teaches your horse to lift its back such as basic dressage will help improve muscle tone. Older horses too, benefit from gentle, muscle building exercise and light riding will help your senior horse’s digestion and joints.