Q. I help manage a 22-year-old Tennessee Walking horse that some years ago had a feed-related episode laminitis episode due to unlimited pasture access. He hasn’t had an episode in five years, and his owner has diligently managed his diet. Due to concerns that he might be metabolic, he gets relatively little grass hay, wears a grazing muzzle in the pasture, and receives a balancer pellet and a small amount of a high-fat supplement. In the last month his weight has dropped significantly. We’re worried and are considering putting him on a newly available senior feed but are concerned about the ingredients, which include sugar beet pulp, molasses, and vegetable oil. This feed’s energy content must be quite high—is that okay for this horse?
—Annamaria, via email
A. You’re right to be careful when creating a feeding plan for a horse with a history of endocrine-induced laminitis. It sounds as though the diet he is currently eating no longer meets his calorie needs and that his calorie intake does need to increase to maintain his condition. I assume you’ve ruled out other common causes of weight loss, such as dental issues or internal parasites? The trick with increasing calorie intake is to do it in a safe way. For horses with metabolic issues, this means increasing the calories while maintaining a low nonstructural carbohydrate (NSC) level in the diet. Ideally, the items in the diet should be kept below 12% whenever possible.
With this horse, his feed’s NSC content should be of more concern than the immediate calorie content. Some high-calorie feeds on the market have NSC levels below the 12% threshold, and some contain all three of the ingredients you mention. Sugar beet pulp is actually a low-NSC feed ingredient, and just because a feed contains molasses doesn’t necessarily mean it’s too high in sugar to be safe. The only way to be sure this feed is suitable is to contact the manufacturer and ask about the NSC content.
You also need to review the feeding directions to see whether the recommended amounts are reasonable for this horse. If you don’t foresee feeding at the recommended level, you might need to continue with some amount of the balancer you are currently feeding to ensure the horse receives adequate minerals and vitamins.
Of course, you could start by increasing the amount of hay being fed, because it sounds as though this horse’s hay intake is currently heavily restricted. This would be my preferred starting point, as long as I knew the hay had a suitably low NSC level. If you don’t know the NSC level, or it’s higher than 12%, consider soaking it for 30 to 60 minutes before feeding it. You might be “getting away with” not soaking it currently due to the relatively small amount being fed. As you increase the total hay intake, the resulting higher levels of NSCs could potentially push him over his threshold and trigger a laminitic event.
One thing to keep in mind with horses in this age bracket is the possible complicating factor of pituitary pars intermedia dysfunction (PPID), especially this time of year (early fall). The seasonal rise in adrenocorticotropic (ACTH) hormone in horses with poorly managed PPID can result in an increase in circulating insulin and potentially an endocrine-induced laminitic event. I am not sure whether the weight this horse has lost is overall condition or, more specifically, lean muscle mass and topline, but horses with PPID can struggle to maintain their topline muscling. If this is, in fact, the cause, your veterinarian will most likely prescribe a drug to help support the PPID, which should help your horse maintain better condition. You might want to consider having your veterinarian assess the horse for PPID in conjunction with making dietary changes.
Taking measures now to increase body condition before we get into winter is very sensible. Start by increasing his grass hay intake. If you do not start to see an improvement in his condition in a couple of weeks or want slightly faster weight gain, I would recommend finding a suitable higher-calorie feed to add to the ration, such as the senior feed you are considering. Remember that NSC content is the concern. Horses with a history of endocrinopathic laminitis don’t have to be on “starvation rations.” Like any horse, they need to be fed to condition, monitored carefully to ensure they do not get beyond a body condition score of 5, and have their diets managed accordingly.