Why Your Horse Isn’t Gaining Weight and What to Do About It

For some horses, it seems like no matter how much they eat, they still stay skinny. I’ve seen cases like this a number of times over the years, and I know how sad and frustrating it can be for owners that want to keep their horses happy and healthy. I put together this guide to help anyone going through a similar situation.

The question then stands, why isn’t your horse gaining weight? There are a number of reasons a horse might not be gaining weight. They are:

    • Parasites 
    • Dental Problems.
    • Gastric Ulcers
    • Poor Quality Feed
    • Reluctancy to Eat
    • Not Enough Food 
    • High Metabolism 
    • Diseases 


With so many possibilities, it can be difficult to tell right off the bat what the cause of a horse’s weight loss is. Let’s look at each of these potential causes to learn how you can recognize them.

Weight Loss Caused by Parasites 

I’m sad to say that parasites are incredibly common in the horse world. With over 100 different types of parasites that can infect a horse, they are frequently responsible for both moderate and severe medical conditions in horses.

The signs that a horse has a parasite aren’t always very clear, but there are some common indicators that you can be on the lookout for. They are:

    • Weight Loss
    • Lack of Appetite
    • Colic
    • Diarrhea
    • Anemia
    • Breathing Trouble
    • Sensitive Abdominal Area
    • Pot Belly
    • Stomach Ulcers and Inflammation
    • Signs of Itchiness
    • Hair Loss


Because there are so many different symptoms, the best thing you can do if you’re concerned that your horse has parasites is to have them thoroughly inspected by a trained veterinarian that will be able to not only tell whether or not they have parasites but also what specific type of parasite it is.

The most common types of parasites found in horses are Roundworms, Stomach Bots, Threadworms, Tapeworms, Pinworms, Bloodworms, Neck Threadworms, Lungworms, and Pinworms.

Different types of parasites require different types of treatments, so it is not recommended that they try to treat the issue yourself without first consulting with a professional.

Weight Loss Caused by Dental Problems

Just like eating can be painful and cumbersome for us whenever we have a sore place in our mouths or a problem with a tooth, the same can be said of horses. Properly taking care of a horse’s teeth not only maintains their happy smile, but it can also prevent them from losing weight.

In order for a horse’s body to properly extract the nutrients from its feed, it must first break down the feed by thoroughly chewing it. If a horse is suffering from any type of oral injury, they are less inclined to chew, and more inclined to immediately swallow their food.

When this happens, their bodies don’t take full advantage of all of the available nutrients so that most of those nutrients leave their bodies when they defecate.

The best way to prevent this issue is to schedule regular oral exams. Some of the clear signs that you should have your horse inspected are swelling of the face, disinterest in eating, bad breath, and nasal discharge. 

Weight Loss Caused by Gastric Ulcers

Gastric ulcers occur when there is an erosion of the lining of a horse’s stomach. Gastric ulcers can occur for a variety of reasons, like stress, long-term solitary confinement, living in urban areas, infrequent feeding, parasites, and certain medications.

One of the issues with gastric ulcers is that many horses display very minimal signs when they have them. However, the symptoms that could indicate stomach ulcers are weight loss, disinterest in eating, a thinning coat, teeth grinding, or a very sensitive abdominal area. 

Just like with parasites, the best course of action to take when you notice any of these symptoms is to consult with your veterinarian right away so they can take medical action if needed.

There are several preventative measures you can take to avoid gastric ulcers, such as ensuring your horse has ready access to hay and grass, doing your best to avoid and limit frequent stressful situations, and allowing your horse out of their stall for long periods throughout the day. 

Weight Loss Caused by Poor Quality Feed

When it comes to a horse’s weight, they need not only a large quantity of feed, but also a high quality of feed in order to put on and maintain a healthy weight.

Even if a horse seems to eat almost constantly, they might not be getting enough nutrition to stay healthy. If the hay you feed them is of poor quality, meaning that it contains plants that aren’t supposed to be in it, or is too old, deficiencies will become apparent as their weight decreases.

The best thing you can do is make sure that you frequently inspect the quality of the hay and forage that is available to your horse. If it is of poor quality, providing high-quality hay can quickly rectify the issue.

If the problem continues even after you switch them to better food, then there is likely a more serious issue going on and you should get help from your veterinarian.

Weight Loss Caused by a Reluctance to Eat

Sometimes, even when you take time to provide your horse with high-quality food, they refuse to eat. Some of the causes of a reluctance to eat are things that I’ve already touched on, but there are several more that you should be aware of.

Sudden Change in Food Options

If your horse has been eating the same thing its entire life and you suddenly switch them to a new diet, they will likely demonstrate some reluctance to eat. In order to prevent this type of negative reaction, it’s best to slowly transition them over to the new diet.

Anxiety or Stress 

There are quite a few reasons a horse could be anxious and stressed. One common reason is separation anxiety as a result of being separated from another horse or being separated from their owner. If you find that your horse is particularly prone to this, it can be helpful to put them in a field with other horses or stable them in a bright and open stable with plenty of other horses around to keep them company.

Poor Living Conditions and Treatment 

A horse that never sees the light of day, or is only taken out for short and intense workout sessions can often demonstrate a reluctance to eat. Make certain that you frequently allow your horse out during the day, and always reward them well for their training sessions.

Illness and Pain 

When a horse is hurting, a symptom that often follows is a loss of appetite. If your horse suddenly loses all interest in eating, it’s with your time to quickly call a vet to see what’s going on.

Weight Loss Caused by Not Enough Food 

This one is pretty straight forward. If your horse doesn’t get enough to eat, they will lose weight just like us when we aren’t properly fed. It can be a little tricky to tell when your horse is being underfed because they will continue grazing, trying to find every last morsel that they can.

You should inspect the fields where your horse goes to feed to make sure that they aren’t overgrazed. If they are, you will need to purchase hay or look at other feeding options.

Weight Loss Caused by a High Metabolism 

Similar to humans, different horses can have different metabolisms which result in weight variations between horses that are being fed the exact same amount. A horse’s metabolism is impacted by factors such as their breed, genetics, and the time of year.

Keep this in mind as your feeding to take special steps to feed additional food to your horse if they seem to have a faster than normal metabolism.

Weight Loss Caused by Diseases 

Diseases are yet another cause of weight loss in horses. There are a large number of diseases that can potentially cause weight loss in horses, but some of the most common ones are kidney and liver diseases, Cancer, Cushings, EPM, EGUS, and HYPP.

Only a trained veterinarian will be able to tell you without a doubt what type of disease, if any, your horse might have.

How to Make a Horse Gain Weight 

You can help your horse gain weight by giving them plenty of quality food that meets their nutritional needs, making sure they have great living conditions where they’re allowed plenty of sunshine and interaction with other horses, and preventing frequent anxiety and stress.

Thank you for reading this article and learning more about horse weight loss and what you can do about it! If you’d like to keep learning about how you can best take care of your horse, be sure to check out my article on Common Horse Injuries and How to Treat Them.

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Carmella Abel, Pro Horse Trainer

Hi! I’m Carmella

My husband and I started Equine Helper to share what we’ve learned about owning and caring for horses. I’ve spent my whole life around horses, and I currently own a POA named Tucker. You can learn more here.

Thank you for reading, and happy trails!

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