How to Put Weight on a Horse Safely: Find the Cause, Then Add Calories the Right Way

By Gayle Woods Editors Updated 5 min read

A horse that's dropping weight or never seems to hold it is a worry, and the natural reaction is to pour in more grain. That can work, but it can also cause colic or laminitis, and it misses the reason the horse is thin in the first place. The best results come from finding the cause, then adding calories in ways the horse's digestive system handles well.

First, check body condition

Weight alone doesn't tell you whether a horse is thin. Use a body condition score, the 1-to-9 scale vets use:

  • Score 3 (thin): ribs easy to see, backbone and hip bones prominent, little fat at the tail head.
  • Score 4 (moderately thin): faint outline of the ribs, slight ridge along the back.
  • Score 5 (ideal): ribs easy to feel but not see, back level.

Feel with your hands, not just your eyes, especially under a winter coat. Record the score and a weight tape reading so you can track progress. See how to measure a horse.

Find the reason the horse is thin

Run through these with your vet:

  • Teeth. Sharp points, loose or missing teeth make chewing painful or inefficient. Look for dropped feed and long hay fibers in the manure. See horse teeth and dental care.
  • Parasites. A fecal egg count shows whether worms are part of the problem. See the deworming guide.
  • Gastric ulcers. Picky eating, girthiness and a sour attitude are common signs, especially in horses in training.
  • Pain. Lameness, a sore back or arthritis can put a horse off its feed and burn energy.
  • Hormone problems. PPID (Cushing's disease) causes muscle loss in older horses. See senior horse care.
  • Herd pressure. A low-ranking horse may get pushed off the hay. Watch at feeding time.
  • Cold weather. Horses burn more calories to stay warm, especially if wet or clipped.
  • Work. A horse in heavy training may simply need more calories than it gets.
  • Not enough feed. Many thin horses just aren't getting enough hay. Weigh it.
  • Illness. Weight loss with fever, diarrhea, coughing or other signs needs a vet.

Fixing the cause is often the biggest single step. Bad teeth floated and an ulcer treated can turn a hard keeper into an easy one.

Step 1: more and better forage

Forage is the safest source of calories because it's what the horse's gut is built for.

  • Offer more hay, up to free choice. Many thin horses do well with 2 to 2.5 percent of body weight a day or more. See how much to feed a horse.
  • Improve the quality. Leafy, early-cut hay has more calories than stemmy, late-cut hay.
  • Add alfalfa. Alfalfa hay, cubes or pellets add calories and high-quality protein. Many owners mix it with grass hay.
  • Try beet pulp. Soaked beet pulp is a highly digestible fiber with more calories than most hay, and it's low in sugar once the molasses is washed out.
  • Use hay cubes or pellets for horses that can't chew long hay well. Soak them.

Step 2: add fat

Fat is the most concentrated source of calories, with about two and a half times the energy of the same weight of grain, and it doesn't cause the sugar spikes that starch does.

  • Vegetable oil. One cup has roughly as many calories as 1 1/2 pounds of oats. Start with about a quarter cup a day and increase slowly over two to three weeks, up to about one to two cups a day for an average horse.
  • Rice bran. Stabilized rice bran is a high-fat supplement, often fed at 1 to 2 pounds a day. Choose one balanced for calcium and phosphorus.
  • High-fat feeds. Many commercial feeds for hard keepers and seniors contain 10 percent fat or more.
  • Fat supplements. Several weight gain supplements are concentrated fat in pellet or powder form.

Horses need time to adjust to fat. Too much too fast can cause loose manure.

Step 3: concentrates, if needed

If forage and fat aren't enough, a feed designed for weight gain or performance can help. See our feed for weight gain picks.

  • Choose a feed that's high in fat and fiber rather than high in starch.
  • Keep each grain meal small, no more than about 5 pounds for an 1,100-pound horse.
  • Feed three or more meals a day if you need a larger total.
  • Increase gradually over 7 to 10 days.

Building muscle, not just fat

A horse can gain fat and still look poor along the topline if it lacks muscle. Muscle needs:

  • Enough quality protein, particularly the amino acid lysine. Alfalfa, soybean meal and ration balancers supply it.
  • Exercise. Regular work, especially hill walking, trotting poles and correct riding, builds the back and hindquarters.

How fast should a horse gain weight?

Healthy weight gain is slow. A reasonable target is about half a pound to a pound a day. Moving up one body condition score in an average horse takes roughly 40 to 50 pounds, which means four to eight weeks or more.

Check progress every two weeks with a weight tape and body condition score. If the horse isn't gaining despite more food, go back to your vet. Something is still burning or blocking those calories.

Refeeding a starved horse

A severely underweight horse, such as a rescue, needs a careful plan. Feeding a starved horse a lot of food, especially grain, can cause refeeding syndrome, a dangerous shift in blood minerals that can be fatal.

General principles, to be worked out with your vet:

  • Start with small, frequent meals of good-quality hay, often alfalfa or an alfalfa mix, several times a day.
  • Increase the amount gradually over about 10 days to two weeks.
  • Avoid grain and sweet feed at first.
  • Provide water and salt.
  • Deal with teeth, parasites and hooves once the horse is stable.

Recovery from severe starvation usually takes months.

Supplements that may help

  • Probiotics and prebiotics may help some horses digest feed better, particularly during stress or after antibiotics. Evidence is mixed.
  • Coat supplements with omega-3 fatty acids add some calories and improve coat shine.

No supplement replaces enough forage and a sound plan.

Sources

Frequently Asked Questions