Why Horses Lose Weight

Learn Why Horses Lose Weight and What You Can Do About It

Skinny white pony

Tim Graham / Alamy Stock Photo

If you have a horse that just isn’t putting on, or maintaining a healthy weight, here are some reasons and what to do. There are several reasons a horse may lose weight, or fail to put on weight despite eating what appears to be a good diet.

The most obvious reason a horse may lose weight is because it is not eating enough. Throughout their lives, horses have different nutritional needs. A young horse should be kept healthy, but not overweight at all, as that brings problems of its own. A young horse should be on the lean side. You should just be able to feel the ribs, but not see them sticking out prominently. Overfeeding at this age may cause joint problems.

Working Horses

As a horse enters its working life, a basic hay or grass diet may not be quite enough. Most horses used for casual riding will be fine, but a horse that is working hard such as a show horse, long distance trail horse, a draft horse used for logging or other high-performance activities may need to be supplemented with grain or other concentrates. Hay or grass may not provide the energy and nutrition it needs. If you are competing with your horse, or riding demanding trails, or hauling logs out of the bush every day, you might notice your horse lose weight and it will need a few extra meals to stay in good shape. It’s not uncommon for broodmares to lose weight as they nurse a foal.

Horse riding in the Vinales valley in Cuba
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Summer Weight Loss

It’s not unusual for horses in the summer months to lose weight. The heat combined with pesky biting insects can run a horse down very quickly. Especially susceptible to the stress of heat and bugs are senior horses and those with very sensitive skins. Many thoroughbreds have this problem. In addition to protection from the heat of the day, and the bites of the mosquitoes and other flies, horses that have problems keeping weight on in summer could benefit from extra feed, whether it’s good-quality hay in the barn where it can relax and eat without fretting at the bugs, or a concentrate or supplement to help put on weight.

Flies on white horse
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Cold Weather

Cold weather means your horse requires more energy for your horse to stay warm. Providing a warm blanket and snug shelter out of the wind and wet will help your horse stay in condition. The best way to keep your horse warm and at a healthy weight is to offer lots of good-quality hay.

Older horses sometimes have problems keeping in good condition. As they age they may not digest food as efficiently, have a harder time staying warm and the aches caused by arthritis or other chronic pain may cause stress leading to weight loss.

Black Horse and dog are walking on the winter snowy bridge
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Dental Problems

The most common reason for weight loss in older horses is dental problems. Horse’s teeth don’t grow forever, and eventually, they may fall out. Even if they haven’t fallen out, they may have sharp edges and hooks that make it difficult and painful for the horse to chew its food efficiently. This particular problem isn’t exclusive to older horses. Many horses in the prime of their lives can have dental problems that interfere with chewing. Regular dental care is important for your horse throughout its lifetime.

Close up of horse eating hay
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Parasites can take their toll on horses at any stage of life. Regular de-worming is essential to avoid a heavy internal parasite load that not only cause weight loss but damage internal organs as well. External parasites can be a problem too. In particular, a virulent lice infestation can cause a horse to lose condition. Foals and older horses may be particularly affected.

Pecking Order

Within a herd of horses, even a small herd such as we keep on our own properties, there are bullies and underdogs. Often the underdogs are bullied away from bale feeders or the best grazing. This can lead to weight loss simply because the horse that is being bullied can’t get enough to eat in addition to being stressed.

White horse standing out in brown and black herd
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Disease and Illness

A number of health problems can cause weight loss. Ulcers are common, especially in performance horses. EPM, HYPP, Cushings, EGUS or Gastric Ulcers, mineral or vitamin deficiencies and diseases such as cancer or kidney and liver disorders can cause appetite and digestive problems leading to weight loss.

What to Do Next

The first step to discovering the cause of the weight loss is to determine exactly how much the horse is eating. This might mean separating it from the other horses for a while. Deworming medication should be administered and don’t underestimate the importance of water in your horse’s diet. Feeding For Weight gain offers some tips for what to feed your lean horse. If after increasing the feed and being sure the horse is dewormed, there is no improvement you may need to consult a veterinarian about checking the horse’s teeth. If after dental work is done, there is still no improvement the veterinarian can take blood samples to ensure there is no condition or disease causing the weight loss.

New Forest Pony drinking from a water trough
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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.