Weighing In On Thin Horses

This in-depth look at putting weight on horses covers everything from ideal protein and calorie counts to measuring a horse's body weight.

Horse owners may no longer adhere to the old credo that “fat is the best color.” However, let a few ribs begin to show and horse owners begin to fret. Stable owners may find boarders sneaking extra hay and grain for their horses or berating owners to other boarders for mismanagement. In the worst-case scenario, a visitor calls local humane authorities to report what they believe is a malnourished animal.

The automatic assumption most horse owners make when their horse drops weight is that the animal is not getting enough feed. Simply increase the horse’s calories, they believe, and everything will be fine again. But, as most horse professionals know, that is usually not the case. Ginger Rich, Ph.D., of Rich Equine Nutritional Consulting based in Eads, Tennessee, says thin horses often present a greater management challenge than overweight animals because temporary or chronic issues may interfere with their ability to utilize what they take in. Simply putting more feed in front of them will not resolve these problems. The solution for each individual horse must be tailored to its specific circumstances.


Rich recommends that stable owners take record photographs of any animals coming into their care as soon as they arrive. If a horse owner later complains about their horse’s weight loss, the horse’s current condition can be compared against these reference photos. Shoot at least one photo of a full side view that shows the horse’s topline and underline clearly. Other photos should be taken at angles that allow the lighting to clearly show any ribs (or patchy fat, as the case may be).

At the same time, use the Henneke scoring system (see page 28) to evaluate the horse’s body condition. Explain the scoring system to the owner and make sure that both of you agree on the horse’s score when it comes into the barn. If problems arise in the future, this gives the stable owner another objective reference point that will be useful in discussions with an owner or veterinarian.

Discuss the horse’s past health history with the owner, ask about the horse’s behavior patterns around other horses, and record the owner’s comments about the horse’s typical work schedule. These may provide clues later on if the horse begins dropping weight.

Finally, Rich recommends that barn managers weigh their horses or learn to use weight tapes accurately (see page 27) so they can weigh or tape the horses in their care on a regular basis. Weekly or monthly measurements taken at the same time of the day are best. Weight changes can occur so incrementally that they go unnoticed until they become a bigger issue. Rich also feels that taping horses regularly can help larger barns manage their feed programs more efficiently and save money.


Horse owners or barn managers need to assess the reason why a horse is losing weight or unable to hold its weight before they start pushing more calories into a thin horse, Rich says. For instance, putting rich grain mixes in front of a truly debilitated horse might literally kill it with kindness. In some cases, the cause may be digestive problems. Or, if the horse cannot chew well because of dental problems, not only will feed intake be affected but a lack of chewing may affect digestion of the feed the horse does eat.

Here are some questions she suggests barn managers and horse owners explore before deciding that a horse’s weight loss is due to a simple calorie deficit or due to the horse’s overall health or environment:

  1. Is the horse leaving feed, or eagerly cleaning its feed tub?
  2. Is more than one horse experiencing weight loss?
  3. Did the barn recently change hay or the grain mixes it feeds? Are augers, hoppers, or other feed storage areas cleaned regularly to prevent dust or mold problems that might create off odors or flavors?
  4. Are extreme weather changes affecting the horse?
  5. Is this a recent weight loss, or has the horse always had difficulty holding weight?
  6. How old is the horse? Could “senior issues” be affecting its feed intake?
  7. Is there sufficient protein in the horse’s diet to maintain muscle and other tissues (see sidebar)?
  8. Has the horse’s workload or competitive schedule increased recently?
  9. Has the horse’s socialization pattern changed recently? Did a barn buddy just leave, is weight loss related to weaning, or has a new horse been introduced into a herd feeding situation?
  10. Does the horse have a history of colic?
  11. Is horse showing signs of poor gut function—watery stools, diarrhea, and flatulence?
  12. Is the horse debilitated because of a recent illness? Have antibiotics been administered?
  13. Does a horse with a poor appetite show any other signs of possible ulcers?
  14. Is the horse dribbling feed or leaving hay cuds?
  15. Is chronic pain such as arthritis interfering with the horse’s appetite?
  16. Could an undiagnosed injury be interfering with the horse’s ability to graze or chew?
  17. Is this a nervous horse that burns up calories pacing, running fence line, weaving, or stall walking?


Insufficient calories for maintenance or work level. If weight loss is occurring because the horse’s caloric intake and workload are mismatched, Rich says the first thing to do is to check the protein level in the overall diet (see page 29). If there is adequate protein, start increasing calories, emphasizing more good quality forage before increasing concentrates (see page 30).

Choose a concentrate that suits the horse’s workload, age, and any special needs the horse may have. Increase concentrates slowly over several weeks, Rich says, adding no more than 1/2 pound daily every 4 to 5 days to give the horse’s digestive tract time to adjust.

Rich says stable managers should not guess about the amounts they are feeding. Use small hanging scales and weight-calibrated feed scoops to keep track of the pounds of forage and grain offered and eaten daily. Feeding by the “scoop” or any other volume measurement rather than weight is very imprecise, she says.

Adding fat to a horse’s ration is an excellent way to increase calories for horses that have trouble holding their weight even as they near the maximum recommended levels of grain, Rich says. Fat can also be a solution for horses that tend to become hyperactive as the amount of concentrates they eat increases. As a rule of thumb, says Rich, 10 percent of the horse’s ration (by weight) is the upper limit for feeding fat.

Depending on the feeding program at an individual barn, there are several ways to add fat to a horse’s diet:

• Pour liquid vegetable oil over the horses’ regular concentrate ration. Horses can eat from 1 to 2 cups of oil a day if the amount can be absorbed by their regular feed. At upper levels, palatability may become an issue. Increase oil slowly and watch for any signs of digestive upset or diarrhea.

• Add stabilized rice bran or ground flaxseed to the horse’s regular concentrates.

• Feed a high-fat commercial grain mix containing up to 10 percent fat (10 pounds of an 8 percent fat feed provides the equivalent of a 1-1/2 cups of oil).

• If you prefer feeding natural whole grains rather than commercial mixes, switch from conventional oats which contain 3 to 4 percent fat to hulless oats which contain 5 to 10 percent fat.

Temporary stresses that put a horse off its feed. Temporarily stressful conditions can depress horses and affect their feed intake, Rich notes. Emphasize forage for these horses, offering hay free choice around the clock if possible, until the horse’s appetite returns.

Competition horses that go off their feed may do better if supplies of the hay and grain they are accustomed to eating at home can be trucked along with them. If that is not possible, Rich says, try to take at least enough of the horse’s regular feed to make changes on the road as gradual as possible. Gradual changes from a previous feed to the feed at a new barn can benefit new boarders, too. Make sure feeds are palatable. Mix chopped carrots or apples into concentrate rations. Don’t overdo this. Limit enticements to 4 to 8 ounces per meal. And remember, says Rich, that horses like other flavors, too. Citrus, peppermint, or cherry flavors are available as liquids that can be poured over feed to tempt depressed appetites.

Weaning, the loss of a favorite barn buddy or even moving to a new stall within the same facility throws many horses off their feed, Rich says. Again, make feeds as palatable as possible. When a loss of socialization is at the root of the horse’s weight loss, consider moving the horse around until it bonds with a new buddy, or consider finding it a pet (racehorses often have chickens, goats or ponies to keep them happy). Any weight loss is likely to be temporary and will resolve itself as the stress is resolved.

Temporarily stressed horses often pass feed through their digestive tract too quickly. They pass small quantities of soft balls frequently, often accompanied by watery liquid. When this happens, feedstuffs do not stay in the gut long enough for the horse to digest all the nutrients. Increasing the amount of forage the horse receives and decreasing fat in the diet can help resolve the problem, Rich says. This should not be confused with true diarrhea, which is a watery slurry rather than soft balls, often explosive, and which can be a veterinary emergency.

Temperamentally nervous horses with finicky appetites. Rich notes that these horses are among the most difficult to keep in good flesh. Start by considering a good veterinary workup to determine if any fretting or irritability may be due to ulcers, parasites, ingested sand or other digestive disorders. With the advice of a veterinarian, she says, consider using probiotics, digestive enzymes, or psyllium fiber, one at a time, in the horse’s diet to check their effectiveness for the particular horse.

Again, if the horse will eat it, offer greater amounts of forage first. The simple act of chewing can help calm nervous horses simply by keeping them busy, Rich says. Also make sure the horse gets the greatest benefit from its concentrate rations. Make feeds more palatable by mixing in tidbits or flavorings. Higher fat feeds pack more calories into a smaller volume of feed, making them excellent choices for picky horses that do not clean up their feed tub. Higher fat feeds can have a calming effect on some horses which, in turn, may help increase feed intake or utilization. Rich advises consulting with your veterinarian before using increased levels of magnesium, thiamine, or herbal mixes to help nervous or irritable horses.

Senior horses that cannot hold weight. Aging horses can have multiple problems that make it difficult for them to maintain weight, Rich says. Their digestive tracts are less efficient and their teeth, even with good care, often make it difficult for them to chew long-stemmed hay or hard grains.

There are many excellent senior complete feeds on the market which combine forage products and concentrates in pelleted or extruded forms. Rich feels, however, that even though the feed may be “complete” nutritionally, many older horses still benefit from some chewing time. Chopped forages are one option for horses whose teeth are not what they used to be. Soaked hay cubes, either of grass hay or a grass/alfalfa mix, are another option. Beet pulp is a very easily digestible, low starch forage choice that can be particularly beneficial for seniors with muscle myopathy or insulin sensitivities, says Rich.

Pecking order and other environmental issues. When horses are fed outdoors in groups, the low man on the totem pole may lose weight. When this happens, changes in feeding protocol are in order. In a field feeding situation, Rich says, make sure there are enough extra feeders so that a timid horse will be able to eat enough before more aggressive horses push him away. Use a feed bag for the thin horse (or use them for the whole group). If possible, bring horses into individual stalls at feeding time, or find another way to feed the thin horse alone so it has time to finish its meal—or get extra forage or concentrates—without being harassed.

Weather changes can adversely affect horses kept outdoors. Particularly when weather gets extremely hot or cold, Rich advises watching horses for signs of dehydration or reduced feed intake. They may need more shelter from the elements, more frequent water changes or, in the winter, a heated water source that encourages them to keep drinking. If a thin horse’s appetite is fine, try to offer forage 24/7 during cold winter months when it not only provides nutrition but also internal heat that helps to keep the horse a little warmer as it digests.

Debilitated or ill horses. If a horse comes into your barn in a malnourished state, be careful not to act too quickly, Rich says. Extremely malnourished animals may need a specially formulated nutritional slurry tube fed by a vet until they regain strength and more normal gut function. Even in less severe cases, begin refeeding a very thin horse slowly to give its digestive bacteria time to adjust.

Start with small, frequent meals of good pasture or grass hay rather than alfalfa. Then offer forage free choice as the horse’s condition improves and it is producing manure normally, she says. Gradually introduce easily-digested feeds, such as the nutritionally balanced concentrates or complete feeds formulated for senior horses that commonly contain beet pulp. As the horse’s condition improves, introduce higher fat mixed feeds, hulless oats or rice bran, and gradually shift to a diet that is normal for the horse’s age and workload as it regains condition. Again, increase concentrates no more than 1/2 pound at a time every 4 or 5 days, backing off if the horse shows any signs of watery or greasy stools.

When illness causes weight loss of more than 100 pounds, refeed the horse gradually, like a malnourished horse, to give its digestive tract time to adjust to the changes, Rich says. Many vets recommend following antibiotic treatments with probiotics and yeasts to help recolonize the horse’s gut bacteria. When horses have undergone gut resection surgery because of colic, they may have absorption problems which will have to be addressed in their feeding program. For example, beet pulp is digested in the hind gut, making it a good feed choice for horses that have lost a portion of their small intestine. Rich advises discussing the horse’s refeeding program with a veterinarian and nutritionist.


To simplify purchasing and feed labor, most large barns offer horse owners limited feed options. A single horse on a special feed creates additional purchasing costs and feed storage issues and adds labor time to the barn’s operations. When these extra costs cannot be met within your existing program, it is time for a heart-to-heart talk with the owner, Rich says.

Consider whether the horse’s weight issues are a temporary or chronic issue. Run the numbers and organize them so that the owner can clearly understand the extra costs. For example, you might ask the owner to purchase any special feeds and supplements herself, then mix and bag them for easy feeding by the staff. When board includes feed costs, this last option will require a downward adjustment. Or the board might be adjusted up to take care of the added costs, Rich suggests. To simplify your life, anticipate the special feeding needs of individual horses when writing your boarding contract, so that all parties understand in advance how the issue will be handled should it come up.

Body Condition Scoring

Veterinarians and researchers use the Henneke scoring system developed at Texas A&M University to quantify a horse’s body condition. The system uses a scale of 1 to 9 to numerically rank the amount of fat that can be seen or felt at various locations on the horse’s body including the neck crest, at the horse’s tailhead, behind the horse’s arm and over the ribs. Using the Henneke scoring system to evaluate each new horse that comes into the barn and updating that assessment quarterly gives barn managers another set of reference points should questions arise about whether an individual horse is getting thinner in their care.

In general, scores from 4 to 6 are considered the healthiest range for horses. Below that, they lack necessary reserves for work or breeding. Above that, they begin to run the health risks that accompany obesity.

1. Poor. This horse is emaciated, a walking skeleton with no fatty tissue at all.

2. Very Thin. This horse is still emaciated but has a slight amount of fat that can be felt along the spine.

3. Thin. The thin horse has enough fat built up along the spine that the transverse processes running horizontally cannot be felt, although vertical spinous processes are still evident.

4. Moderately Thin. This horse’s ribs are still faintly visible and the spinous processes running vertically along the spine are just barely evident. The withers, shoulders and neck no longer look bony and thin.

5. Moderate. The horse’s ribs can no longer be seen but they can still be felt. The horse’s back is flat with neither a ridge nor a crease. Some spongy fat is beginning to accumulate around her tailhead, but overall the horse presents a smooth appearance.

6. Moderately fleshy. A slight crease is developing down the horse’s back. Fat can be felt over the ribs and around the tailhead. Accumulations of fat are beginning to show along the neck, just behind the withers and behind the arm and shoulder.

7. Fleshy. The crease along the back may be more distinct. Although individual ribs can be felt, there is also palpable fat accumulating between the ribs. There is more fat deposited at the neck, withers, shoulders and tailhead.

8. Fat. There is a distinct crease down the back, and ribs can no longer be felt. There is noticeable thickening of the crest and fatty deposits behind the withers, behind the shoulders and in the inner thighs.

9. Extremely fat. Besides a deep crease down the back, the horse’s fat accumulations are now so visibly noticeable that they give the horse a “patchy” appearance. Fat accumulation may make the inner thighs rub together and the flanks are filled with fat.

—SOURCE: Adapted from Henneke et al (1983)






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