While some Thoroughbred horses seem to be easy keepers, you will find that some of them struggle to maintain their weight. Usually, whatever is causing your Thoroughbred’s weight loss or lack of weight gain can be easily remedied.

There are several things you can adjust about your Thoroughbred horse’s day-to-day regimen to help it gain and then maintain its weight.
Knowing the steps that you can take to help your Thoroughbred get to a healthy weight is half the battle. The other part is finding out which remedies apply to and will help your horse specifically.
Table of Contents
1. Get Your Horse’s Teeth Checked
If your Thoroughbred horse is having trouble putting on weight, try checking its teeth first.
Sometimes a horse will simply need its teeth floated, or filed down, to remove sharp pieces or uneven teeth that are causing pain and preventing adequate chewing.
A bad tooth or an infection could also be causing the problem and may need medical attention. (source)
Worn down teeth could also prevent your horse from properly chewing its food or being able to eat certain foods. This can lead to weight loss and prevent weight gain when needed.
Work with your veterinarian to find the best food for a horse that is missing a lot of teeth. (source)
2. Have a Vet Check Your Horse for Worms
A significant worm infestation in a Thoroughbred horse can cause a decreased appetite, resulting in weight loss and malnutrition.
Many times, no matter what you feed a parasite-ridden horse, it will be unable to gain weight.
You should consult a vet as soon as possible to determine the best wormer for your horse.

Skin issues, hair loss, poor coat quality, lack of appetite, and lethargy are all signs of a worm infestation in horses.
With the right plan and the best wormer, you can help your Thoroughbred ward off parasites and hopefully gain weight as a result. (source)
3. Make Sure You Are Feeding the Recommended Amounts
Many Thoroughbred horse owners that have a ‘hard keeper’ often find out that they are not feeding the recommended amount for their horse.
Purchase a food scale so that you can measure the amount of feed and hay that you feed each day. Suggested feeding amounts for grain are often listed on the product bag.
For hay, horses should eat around 2 percent of their weight in forage each day. They will need more to gain weight.
Sometimes, just feeding the correct recommended amount of feed to your Thoroughbred horse is the answer to your problem.
4. Adjust Your Feeding Regimen Based on Activity Level
Thoroughbreds, especially those that compete or exercise regularly, need extra calories to keep them from losing weight. Their metabolisms are often faster than horses of other breeds.
Your Thoroughbred’s diet should match his or her activity level and it may need to be adjusted regularly.
Horses that are working harder than normal should be fed more to compensate for the expended energy.
5. Feed Your Horse Extra Forage
If your horse is already eating the recommended amount of forage, try adding some extra hay or richer pasture to their diet.
You can gradually increase the amount of hay in your Thoroughbred’s daily diet to around 2.5 percent of their target weight.
Free choice hay or grass of high quality is best.

If possible, allow your horse access to grass or hay or a combination of both throughout the day. If this is not possible, consider adding more hay to your horse’s regular meals. (source)
6. Add Grain to Your Horse’s Diet
If you do not already feed grain to your Thoroughbred, consider adding it to your horse’s diet to help it gain weight. Grain should be introduced slowly and forage should still remain the bulk of their diet.
Grain is a great high-calorie option to help a thin horse or an active working horse gain weight when needed. It can be fed at regular intervals with forage throughout the day to avoid gastric upset.
Follow the instructions on the back of the bag to help determine the amount your horse will need each day. (source)
7. Add High Calorie Supplements to Your Horse’s Diet
Thoroughbreds typically function with a faster metabolism than other horse breeds, which means they need more calories in their diets than some other horses.
An underweight Thoroughbred requires even more energy, or calories, to help it gain weight. (source)
Try adding high fiber supplemental foods such as beet pulp or soy hulls to your Thoroughbred’s regular diet.
Other high fiber foods, such as wheat bran and alfalfa pellets, when fed in moderation, can help supplement poor forage qualities.
High starch supplement foods such as processed corn or oats can help increase the energy in a horse’s diet. Whole corn is not recommended because it is harder for horses to digest.
Supplemental fat sources can also be added to your Thoroughbred’s diet to help them gain weight more quickly.
Rice bran, corn oil, and linseed are all great sources of fat, and therefore energy, for Thoroughbred horses.
Work with your veterinarian to find the best supplemental food options for your specific Thoroughbred. (source)
8. Add Vitamin Supplements

Vitamin B helps Thoroughbred horses extract more calories from their food. It promotes digestive health and allows horses to absorb more nutrients from their food.
Vitamin B is also known to improve a horse’s appetite.
9. Increase the Number of Feedings
If you feed your Thoroughbred twice a day, consider feeding him or her three times a day instead.
By increasing the number of feedings, you will increase the horse’s daily caloric intake.
This may help to add weight to your horse if too few calories are causing the lack of weight gain. Keep meals spaced throughout the day to give your horse time to digest its food properly.
10. Have a Vet Check for Undiagnosed Diseases
If nothing else seems to be helping your Thoroughbred gain weight, you may need a veterinarian to check your horse for undiagnosed diseases.
Insulin-resistance, anemia, kidney disease, and Cushing’s disease can all cause weight gain issues in Thoroughbred horses. Chronic infections and gastric ulcers can also cause weight loss.
If your vet discovers an illness, you can work with him or her to establish a treatment plan as soon as possible. (source)
11. Feed Separately from the Rest of the Herd

If you have multiple horses in the same enclosure, a natural hierarchy will be established within the herd. This can often lead to weaker horses not getting a turn at the hay bin or food trough.
Watch the social dynamic if you suspect this is the case and see if your hard-keeper Thoroughbred is just not getting a chance to eat.
You can separate the horses at feeding time or, if that is not an option, you can try incorporating multiple feeders spaced apart from one another.
This may give your horse a better chance at getting his or her fair share of hay or grain. (source)
12. Adjust to Environmental Changes
Thoroughbred horses expend energy trying to keep cool in the warm months and when struggling to stay warm during the winter. Extreme temperatures can also make horses less inclined to eat.
Provide adequate shelter for your Thoroughbred during harsh weather, including hot sunny days and cold winter nights. Use blankets in the winter to help them stay warm and expend less energy.
13. Provide Plenty of Water
Horses need a constant supply of water to avoid becoming dehydrated. Dehydration can cause a lack of appetite and prevent a horse from eating its normal food, which can hinder weight gain.
Make sure your Thoroughbred horse has fresh water, especially during the winter when water can easily freeze.
If the horse regularly runs out of water, consider an extra bucket, container, or an automatic waterer. Running out of water daily is a signal they need a more constant supply. (source)
How to Monitor Your Horse’s Weight Gain
If you do not own a large animal scale, then you will need to use other methods to track your Thoroughbred’s weight progress. Luckily, there are a few tricks you can use to easily monitor your horse’s weight gain.
1. Use a Measuring Tape

You can use a soft measuring tape (like this one ), preferably made for horses, to measure your horse’s size.
Measure the girth area at the beginning of your endeavor and periodically to track any changes. You are looking for the inches to increase as the horse gains weight.
2. Use a Chart or Journal to Track Progress
Write down the horse’s progress on a chart or in a journal so that you can really see the changes.
This is good not only for your own memory, but also gives you a record to show your veterinarian.
3. Take Pictures
It is difficult to see positive changes in your horse’s weight when you see him or her each day.
Take a picture now to establish a baseline visual reminder of where your horse started. This will help you compare your horse’s progress visually, which helps you really see the positive changes.
For more information about measuring your horse’s weight, check out this post: 11 Ways to Measure a Horse’s Weight.
Final Thoughts
Getting your Thoroughbred to gain weight can seem a little overwhelming, but a lot of these options are easy to implement or discard if they do not apply to your horse.
Many Thoroughbreds will struggle at some point in their lives to gain or even maintain a healthy weight, thanks to their fast metabolic rate.
The important thing is to spot issues early on so that you can make some changes as soon as possible. Not every Thoroughbred horse is the same, but that is what we love about them, right?