What do you feed a horse with laminitis? Nothing, plus a bit of hay is a common diet. Does it work? Yes, and no. Expert opinions and modern research are showing that, in some cases, nothing might be the wrong answer when it comes to feedstuffs, and that simple flake of hay might not be as harmless as you think.

This article isn’t going to be about the causes and treatments of acute or chronic laminitis; rather, it’s going to be about feeding those affected horses to help them return to health, or at least not push them toward another laminitis episode. For background on the causes of laminitis, foot physiology, or what makes a laminitis-prone horse, see the list of further reading at the end of the article.

Know Your Horse

“I think the most important thing in any type of feeding situation is to know the condition of the animal,” says Doug Butler, PhD, an award-winning farrier with a PhD in veterinary anatomy. He uses the Henneke Body Condition Scoring system to evaluate a horse’s condition (see “Body Condition Scoring” on page 78).

“If an animal is very heavy, the owner would want to reduce its weight,” he explains. “Or if it’s very thin, the owner wouldn’t want to cheat it. (That horse) needs all the nutrition he can get to get well.”

The optimum score for most horses would be a five, although this can vary by breed. One example is a Thoroughbred; some show their ribs even when they are in great condition, and many have very high withers that result in a lower score. Butler also notes that ponies need special consideration in feeding, particularly with laminitis, since they are more efficient food processors.

Once the horse or pony has been properly evaluated for body condition, Butler says any weight adjustment needs to be handled carefully. On a low-scoring horse, you want to increase weight without making the founder worse. A major risk is giving these horses too much feed in a single feeding, because then they can easily get more starch than they can handle.

With an overweight horse, the owner needs to decrease weight without causing stress. Laminitis itself is a stress, so it’s best to not stress them further. If we stress the horse further by starving him, we’re not going to be helping him much. On the other hand, a fat horse is more likely to become stressed by small incidents, such as travel. “It doesn’t take much to put him over the top,” says Butler.

“When you change feed on a horse, you need to do it over a period of about five days,” says Butler. “This slow change is because the bacteria in the gut are what the horse relies on to digest the food, and those flora change slowly.” In other words, good gut flora changes that maintain an equilibrium take time, although bad changes such as overgrowth of toxin-producting bacteria following starch overload can happen very quickly. So if you change immediately from one feed to another, you’ll do more harm than good.

“Hopefully, you don’t have to change the feed, all you have to do is reduce the quantity,” Butler continues. “When an animal is being fed too much, as is the case with many horses that founder nowadays, you just cut down the quantity. You don’t change the feed, just the amount.” The amount fed depends on the nutrient content of the feed (grass, hay, and grain) and horse’s energy requirement.

Butler feeds hay, not grain. “I believe a horse needs only roughage unless he’s got some really big reason such as he’s being worked real hard, or it’s a mare that’s lactating,” says Butler. “Otherwise, the only time I give horses grain is when I want to catch them. And maybe to reward them for training.”

Of course, there are exceptions for horses with debilitating conditions; poor absorption; young, growing horses; or hard keepers.

In addition to supporting a thin or low-scoring horse, Butler does not believe in cutting feed if the laminitis has a non-food cause, such as from a retained placenta in a mare. “Then I would not reduce the quantity of feed because they’re going to need all the food they can get to get over that terrible disease,” he says. “By doing what many people do, which is to immediately cut back and give them real poor-quality grass hay, that’s not going to help the horse at all. The horse will likely go downhill then.

“That’s not traditional thinking,” Butler adds. “There’re a lot of people who will tell you as soon as the horse gets laminitis, pull the feed and give them poor-quality hay; I think that’s a big mistake.”

The Role of Grass and Hay

Kathryn Watts, of Center, Colo., has a BS in crop/soil science from Michigan State, and she operates Rocky Mountain Research and Consulting. She also has two severely insulin-resistant and laminitis-prone ponies, even when their body condition scores are at 5. Her research into how to care for her own horses has led her to become an activist for more informed choices in feed and grass varieties.

“I have found that chronic laminitis is often due to a metabolic abnormality whose root is insulin resistance,” she says. “We can control metabolically induced laminitis by limiting high-glycemic feeds (those that induce a high glycemic response, or a large spike in blood sugar following a meal).” This includes grain, some grass, and maybe even that “poor-quality” hay. (Some grasses can be very high in carbohydrates and thus bad for the laminitic horse.)

With an acute laminitis attack, Watts recommends getting horses off all grain and grass immediately and into a dry lot. She prefers a lot to a stall so the horse can exercise if he chooses. However, if a horse is being given pain medication, excess walking might cause further injury and a stall might be the best choice.

For laminitic horses, she also recommends getting baseline insulin and glucose tests for insulin resistance and plasma adrenocorticotropin (ACTH) to check for early-stage Cushing’s disease. Keep in mind that these will give false positives if the horse is in the acute stage of laminitis and is in pain, and also if the horse just ate grain. Her tip for getting fast test results is to send your sample directly to a testing site. If you send a sample to a lab that has to send it to another lab, results can take weeks. At the same time, see what your horse is eating.

To understand the factors affecting the carbohydrate content of grass, we need to look at the composition of grass. Grass cell walls are made of structural carbohydrates. This becomes dietary fiber, which is good for horses. Non-structural carbohydrates are sugars and starches stored in the cell interior. These fuels help plants grow, and have a high glycemic index (generate a large spike in blood sugar following a meal)–exactly what should be avoided for the overweight or insulin-resistant individual. Unfortunately, those sugars are the stuff that tastes good, so horses seek them out.

Unfortunately, you can’t judge grass (or hay) by looking. Watts has seen her horses charge directly for an area where the grass has had less irrigation water. It might be “spindle and sorry-looking” to us, but it has higher sugar and therefore better taste. Avoid grazing after a frost, but encourage grazing in the morning when plants have spent the night converting all their resources gathered from photosynthesis during the day into less digestible fiber components.

Fields need to be kept mowed to keep the grass from coming to a head. “The seed head is a sink for carbohydrates,” says Watts. Horses can taste the difference and will nip off the heads like “horse candy.” On the other hand, overgrazing can put pressure on the grass and promotes the most vigorous and competitive grasses. “That is the definition of high-sugar grass,” she says.

Watts finds the common laminitis adage of avoiding lush grass in spring and fall to be right, but not just because it’s green or lush. In the spring and fall, the nights are often below freezing in many areas. There are also other reasons for the higher sugar at these times, i.e., rapid growth concentrating sugars in the grass.

Since grass becomes hay, the same rules apply. The carbohydrate content can vary from bale to bale depending on drought stress, fertilizer, or even the time of day it is cut. If hay is cut in the afternoon (although this is rare as it reduces that day’s drying time), the grass has had all day to accumulate photosynthetic sugars.

Non-structural sugar content (NSC, which includes several types of carbohydrates that are soluble in neutral detergent) is also related to climate. “The photosynthetic rate is directly correlated to sunshine,” says Watts. “In a cloudy climate, plants can’t make as much sugar.” Sarah Ralston, VMD, professor in the Department of Animal Science at Cook College in New Brunswick, N.J., the agricultural branch of Rutgers University, had trouble finding samples of high-sugar hay in her area. However, living in an area with little to no high-sugar hay doesn’t mean you’re risk-free–if you import hay from another area, you should consider the climate in which the hay was grown when hay shopping. Better yet, have it tested (more on this shortly).

Watts has been sent samples of hay that are as much as 30% sugar, starch, and fructan. Fructans are a type of sugar that Chris Pollitt, BVSc, PhD, of the Australian Equine Laminitis Research Unit at the University of Queensland, has reported to be linked with the production of toxins in the colon and subsequent changes in the bloodstream that lead to laminitis. (For the latest on Pollitt’s work, see “The Australian Take on Laminitis” on page 47.)

An average sugar percentage for grass hay ranges from about 6-15%. However, it can be anything from 3-40%, based on Watts’ and Ralston’s experience. Watts has found that getting the percentage of sugar and starch below 10% in hays fed to laminitic horses can lead to dramatic improvement in as little as two days to two weeks.

However, it isn’t a matter of food deprivation. Watts explains, “These horses can often have more hay once you find one that is low in sugar,” she says. “Then you can feed more often and avoid the feed-fast cycle (where a horse has a lot of time each day with no food available–the ‘fast’–in between large meals–the ‘feed’) that promotes fluctuations in glucose and insulin.”

Since you can’t tell the sugar content in hay from looking at it, it needs to be tested. Sometimes what looks like poor-quality hay can have high sugar levels even when a conventional hay test shows low protein and minerals. Watts admits this can be difficult. She has run into resistance from farmers and has had hay deals fall through while she waits for test results. However, a horse owner can’t take pot-luck. “To manage a horse with chronic laminitis, you must know what they are eating,” she stresses.

What can you feed a horse with hot feet while you do all this research? Watts has found that soaking hay for about an hour can get rid of up to 56% of its water-soluble carbohydrates. Be careful of soaking it too long, warns Ralston; you might get mold that will compound the problems, especially in hot, humid weather. If it is necessary to give the “grain-starved” horse something to keep him calm at feeding time, you can give him soaked hay cubes. (For more information on high-carbohydrate grasses and Watts, see www.safergrass.org.)

Once Bitten…

Ralston is in the middle of the very type of equine-related forage research that Watts has been hoping for. She explains that it is important to identify the cause of the laminitis attack. Even though the physiologic effect on the foot is the same, the initial cause will determine how you manage the horse in the future.

Just because a horse has had laminitis once doesn’t mean that he has it for life. For the classic laminitis example, a horse getting into the feed room, Ralston’s advice is simple: “Lock your feed room”–provided, of course, the horse has no extenuating circumstances or prior history with laminitis. Butler’s advice is that if there has been enough damage to merit corrective shoeing, consider the horse susceptible to another attack, at least for the next six months (the approximate time it takes for the new, healthy hoof to completely grow out).

Therefore, on the day of an acute laminitis attack, the feeding regime will depend on the cause. For that grain overload or grass founder, Ralston recommends some low-carbohydrate grass hay to give them something to munch on. For a mare with endotoxemia from a retained placenta, feed “anything that will get her to eat.”

Take-Home Message

Feeding a laminitic horse isn’t often easy, particularly when food was the cause of the laminitis. But your laminitic horse can’t live without food, so you must feed him just what he needs to stay healthy. With the advice of a veterinarian and/or nutritionist, you can use diet to minimize further laminitic insults to your horse’s hooves and help him live a more comfortable life. 

FURTHER READING

Diehl, Nancy. Feeding Laminitic Broodmares. The Horse, June 2002, 111. www.TheHorse.com/ViewArticle.aspx?id=3625