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How Much Weight Does a Horse Lose In a Race?

Last updated: November 18, 2022

By: Miles HenryFact Checked

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If you have ever been to a horse race in Louisiana, it was likely on a hot. Horses running in Louisiana heat lose a lot of weight. They are big animals, pushing their bodies to extreme levels. So let’s look at numbers and facts about the amount of weight a racehorse loses during a race.

A horse can lose up to 5% of his body weight in a one-mile race; for an average-sized Thoroughbred, this calculates to more than 50 lbs. The majority of weight loss in a race is fluid.

Horses burn lots of calories and lose fluids during regular exercise, but when the weight they lose is staggering.

Weight loss of horses during a race

The majority of weight loss in horses during the race is fluid loss. A horse’s body generates heat which in turn causes the horse to sweat. Fluid deficits of 4-7% of body weight after a one-mile race have been confirmed in some studies.

The amount of fluid and electrolyte loss during a race is influenced by temperature, humidity, and the length of the race. Horses must be properly hydrated before a race and rehydrated after a race to prevent illness.

Picture of horse leaving the gates from their post position.

High fluid losses increase the animal’s risk of dehydration, which in turn leads to elevated core temperatures in horses and a dangerous loss of electrolytes.

Water is certainly the most important nutrient for horses that are overheated, but electrolyte supplements are needed to help replenish the electrolytes lost during a race. Farnam Apple Elite Electrolyte is a good equine supplement you can order from Amazon.

How Long Will it Take for A Racehorse to Regain the Weight he lost During a Race?

Of course, temperature, humidity, and fitness level determine how much a horse will sweat during the race. If the racehorse is in peak physical fitness, he should be able to regain the lost pounds within two to three days. Some horses have the capability to make a full recovery within 24 hours after a race.

How Much Does an Average Racehorse Weigh?

It’s difficult to determine the average weight of a racehorse because this information is not required by the tracks. However, the average thoroughbred racehorse most likely weighs 1150 pounds. Racehorses are watched by trainers to determine their optimal race weight.

Many trainers work with their horses daily and use their vast horse knowledge (judgment of the eye) to monitor the horses’ fitness, while others use scales.

Trainers with scales will weigh their horses both before and after races and workouts and log the information. Weighing a horse puts numbers in place of guessing, but even with having scales judging a horse’s peak fitness level isn’t an exact science.

Horses, like humans, are individuals, and many factors go into success. The key is to know your horse and how his body naturally varies over time.

How Much Does A Baby Horse Weigh?

The general rule is the newborn foal should weigh about 10 percent of the mother’s weight. So if the mare weighed 1,000 lbs, her foal should weigh 100 lbs. This can be applied across breeds.

To weigh a newborn, it is easiest first to get your weight, then lift the foal and step on the scales. The difference is the weight of the foal. The sex of the foal has played no factor in how much a newborn weighs.

A filly and colt should weigh the same. The normal gestation cycle for a horse is 340 days; if the foal is delivered early, the foal may be smaller than normal.

If you believe your foal was born premature, call your vet immediately. A normal foal should be capable of standing within two to three hours of birth and soon after begin nursing.

How Much Does an Average Thoroughbred Weigh?

The average mature five-year-old thoroughbred weighs roughly 1,256 pounds.  Thoroughbred horses grow until they’re five, but that doesn’t necessarily mean they continue to put on weight.

Some horses may weigh more at two than five years old. Horses replace fatty tissue with more muscle, becoming leaner. Factors that determine the size and shape of a horse are genetics, training, feeding routine, and its environment.

How does Traveling Affect a Horse’s Weight?

Traveling is a major factor in the weight loss of a horse. Horses tend to avoid eating and drinking as much as normal when being transported. This leads to losing weight.

The further the distance a horse has to travel for a competition, the more weight they normally lose. Traveling affects less seasoned horses more than experienced travelers. A young horse is likely to get off its feed after a race.

Make plans to keep your horse hydrated during travel; this may require frequent stops to allow the horse to exit the trailer and walk. A trainer should know his horse and plan accordingly.

Some horses will travel more comfortably with a stablemate or a dog. Whatever works to keep a horse healthy during travel should be done.

Can Weight Loss Be a Sign of Trouble?

Yes, weight loss can indicate a potential problem before other symptoms are noticeable. Some of the more common reasons a horse will lose weight are:

Reasons a horse loses weight


A horse may continue to eat his normal amount of hay and feed but lose weight. The first thing to consider is a change in hay and feed quality.

It is not uncommon to get a load of subpar hay; all hay is not the same, even if purchased from the same distributor. The same goes for feed. Also, the horses’ nutritional needs change over time.

Adding a supplement to the feed of vitamins and minerals may be necessary to help the horse maintain a proper weight.


If your horse is on a proper diet and still losing weight, the next step is to consider a disease being the cause of the weight loss. Blood testing in horses that lose weight while eating normal healthy diets has low amounts of albumin.

Albumin is synthesized in the liver and helps transport hormones and other compounds. Low albumin can indicate problems associated with the liver, kidney, or bowels. You need to have your horse seen by a veterinarian, and this issue could lead to serious health conditions and even death.

Dental Problems

Horse teeth need to be checked and floated regularly. There are many dental conditions horses develop that lead to ineffective chewing and digestion. Dental problems lead to weight loss in an otherwise healthy horse.


Horses must be on a regular worming schedule. Internal parasites will lead to weight loss and can also cause damage to a horse’s organs. Click here to check the prices of Ivermectin Paste Dewormer sold on Amazon.

Flies and mosquitoes are not only aggravating to a horse; they can also carry disease. (click here to read our article on horseflies)

Cold Weather

During cold weather, horses expend more energy to keep their bodies warm than they do during warmer weather. Because they are burning more energy to stay warm, they lose weight while still eating the same amount of feed and hay.

Adjust their dietary intake of feed and hay upwards to compensate for the use of extra energy during cold weather.

Hot Weather

Horses will also lose weight during hot weather. Heat and pests are a combination destined to cause stress, hair, and weight loss in a horse. If a horse is stall kept, place a fan in the barn to keep air circulating.

Air movement is one method to cool the animal as well as prevent some flying insects from the horse.

Pecking Order

If you have more than one horse, there is likely going to be a bully. The weaker horse will be kept from his feed unless the horses are kept separate at feeding times.

If you suspect a problem, the first thing to do is feed the animals separately so you can monitor each horse’s intake of food.

Picture of a two year old horse

What is a Good Weight For a Horse?

Don Henneke, Ph.D., developed a set of visual and palpable test methods to determine the body fat of a horse called the Henneke Body Condition Scoring System(BCS).

It is widely used by some law enforcement when making a determination about horse abuse and neglect. The BCS uses the Henneke Chart to standardize the scoring system to apply objective factors.

The Henneke Body Condition Scoring System checks six parts of a horse—the neck, withers, shoulder, ribs, loin, and tailhead. When checking the areas, you must apply a firm press on the body.

When you press on the ribs, you must be able to feel the fat covering the bones and be able to determine how much fat is present. When you feel the withers, it should feel like you are squeezing firm clay in your hands.

During the process of checking each of the six areas, you assign a number for the horse’s condition in that area. Once you have a number for each area, you total the numbers and divide them by six.

This number is the animal’s Henneke Body Scoring Condition. The scoring is based on a ranking of 1-9. 1 is considered to be emaciated, with no body fat, and nine is obese. An acceptable score falls between 4 and 7, with five being ideal.

The BCS can be applied to any breed of horse to determine its ideal weight. (You can read more about the Henneke Body Scoring Condition here)

How Can You Tell If a Horse is Overweight?

The best way to check if your horse is overweight is by using the Henneke Body Scoring Condition Chart discussed above. However, there are additional methods, such as the Girth to Height Ratio method.

The girth-to-height ratio is a calculation based on the measurement of the girth divided by the height measurement. A horse is considered overweight if the girth-to-height ratio is equal to or greater than 1.26.

The measurements are to be taken at the top of the withers. (click here to order a good weight tape for your horseir?t=horseracin05a 20&l=am2&o=1&a=B000AA4DBM)

Another method to determine if your horse is overweight is called the Cresty Neck Score. The cresty neck score evaluates the fat in the neck of an animal.

This scoring system uses a range from 0 to 5. A score of five would be used for a crest so large it falls to one side, and a zero would be used to indicate no crest is visible.

The ideal score would be a two or lower, and the horse would be considered overweight if the score is higher than a two. There are also ideal body weight equations owners can use to determine if a horse is overweight. These involve the use of apps and specific areas of measurement.

These app-based calculations can give you insight by breed. This information can be beneficial when used to calculate the dosage of medicine and when dealing with non-traditional horse breeds.


How Much Does a Quarter Horse Weigh?

Quarter horses are thickly muscled athletic horses. They carry their weight differently than Thoroughbreds and are shorter, but the two breeds weigh roughly the same weight, 1200 lbs.

Just like humans, all horses are individuals, and some quarter horses are specifically bred to be on the lighter weight end and some on the heavier side, but 1200 lbs is a good average.

How Much Does Justify the Racehorse Weigh

Justify won the 2018 Triple Crown, becoming just the 13th horse to accomplish this feat. But how much does he weigh? Justify is a big horse. We know he stands 16.3 hands tall, but his weight is just a guess. When Justify was sold at the Keeneland Yearling Sale, his weight was listed at 1,050 lbs.

At the Preakness Stakes, it was reported that his weight was 1,268 lbs; however, many believe he weighs close to 1,400 lbs. What is Justify’s true weight? It is probably somewhere in between, but it is just a guessing game unless Bob Baffert releases the information to the public.

Below is a helpful YouTube video on how to find your horse’s weight.

Miles Henry