Laminitis is a very serious condition in horses that is often associated with metabolic problems, especially insulin dysregulation (ID). “Obese horses may be at higher risk for becoming ID and suffering from laminitis, but lean animals can also develop laminitis, especially if they are insulin-dysregulated,” said Patricia Harris, PhD, VetMB, Dipl. ECVCN, MRCVS, during her presentation at the 2023 American College of Veterinary Internal Medicine forum, held June 15-17 in Philadelphia, Pennsylvania.

While nutrition isn’t the only way to manage horses prone to laminitis, it’s an important factor to consider, and veterinarians, nutritionists, and horse owners need to work together to ensure this piece of the horse’s management is in place.

Complementary Feeds for Horses With Laminitis

If horse owners know their animal has ID and is, therefore, at a higher risk of developing laminitis or has had a laminitic episode in the past, they should remove all cereal-based feeds (e.g., containing oats, barley corn etc., grains), said Harris, and replace them with feeds low in nonstructural carbohydrates (NSCs, starch, and water-soluble carbohydrates ) with the goal of producing a low post-meal insulin response. If the horse needs to gain weight, then it might be worth considering adding vegetable oil to the feed gradually (supported by additional vitamin E) or use a commercial high oil, low NSC fortified feed, and increase the number of meals fed. “When switching a horse to a low-NSC diet, it is however essential to maintain nutritional adequacy, which may require the use of a balancer, especially for those on forage-only or forage-restricted diets,” said Harris. This will help avoid creating various nutritional deficiencies in your horse.

“Low-NSC chaff can be a good option for extending mealtimes so that the horses can spend more time chewing,” she added.

Horses with severe ID can have an exaggerated insulinemic response  even with small meals, noted Harris, unless the meals are very low in NSC. These horses should be monitored very closely by owners and veterinarians. Checking the insulin response of an individual animal to its own feed and forage can be very informative, and it can be invaluable to obtain specialist nutritional advice based on these results.

Pasture and Forage for Horses With Laminitis

Pasture grazing, especially at certain times of the year, can result in an overload of water-soluble carbohydrates (which include the simple sugars), especially for horses with ID. These horses might need to be turned out on a dry-lot or just onto pasture for example very early in the morning and brought in before lunch, said Harris. “During the daytime, especially if warm and sunny, WSC levels typically increase in cool-season grasses, and overnight those levels go down.” However, this depends on many environmental factors, so working with an equine nutritionist, especially one with knowledge of local weather and pasture conditions, can be very helpful, she added.

For horses that cannot be turned out on pasture at any time, a dry-lot with hay might be the best solution. “I typically recommend feeding more mature forage because it is generally lower in energy and WSC content,” said Harris. “However, it is important to test the NSC and, especially, the WSC content of the hay for ID horses, using an appropriate experienced laboratory, because there is significant variability between different hays, and you cannot guess the WSC content by looking.”

Horse owners can soak their horse’s hay to reduce WSC levels, but the actual percentage lost is highly variable and might not be sufficient. Therefore, if concerned owners have already tested their hay to be sure it is safe for their horse to eat, they can use soaking as an additional measure. Owners should also be aware that soaking can cause the hay to lose dry matter, which is important when formulating a weight-loss program and results in leaching of other nutrients. In these cases, feeding a balancer becomes even more important, said Harris.                                                                                                                                                      

Managing a Horse’s Diet During Laminitis Episodes

If your horse has a laminitic episode, the first step is always to contact your veterinarian. As far as dietary management, remove the possible nutritional causes (e.g., take the horse off pasture and any feeds containing moderate to high NSC levels, especially cereal grains) and put them on a lower-NSC hay if the one you’re feeding is too high, said Harris. “Often you will be asked initially to house the horse in a dry-lot or box stall without access to pasture and (to) feed a low-NSC preserved dry forage.” Because this involves sudden changes to the diet—something veterinarians and nutritionists typically don’t advise in normal horses—owners should monitor their horses carefully, especially for signs of colic.

After a laminitic episode, checking your horse’s ID status periodically can be invaluable over the years to help guide the ongoing feeding program. Monitoring insulin response to increasing periods of turnout can be essential for some laminitic horses in their recovery phase. However, it is important to recognize that in the months and even years following the episode, some horses might always need to be kept in a dry-lot or only be allowed on pasture for short periods with a grazing muzzle. For those that do get pasture access, you might need to limit it to certain times of the day or year. And for horses prone to being overweight, it is especially important that owners work to reduce their horses’ weight and maintain a healthier weight through exercise and dietary management.

“In managing laminitis-prone animals it is important to think not only about their nutrition but also their exercise program,” said Harris. “Whenever possible, it can help to increase their exercise; even 15 minutes of trotting a few days per week can improve their insulin sensitivity.”

Take-Home Message

For a laminitic horse to survive and thrive, veterinarians, nutritionists, and owners must work together to create a specific plan for preventing future episodes. Dietary changes are crucial to this effort, said Harris, but are unlikely to be successful without accompanying management changes and, in some cases, medical management (the use of medications for treatment).