Carbs & Horses: Separating fact from fiction

The gal at one of the feed stores is making this BIG deal out of controlled starches. I always thought that only horses with certain issues [i.e. insulin problems, EPSM, and laminitis] required carb consistency. Any issues with malnourished horses? Also, if this is an issue with malnourished horses, is there a certain hay that tends to provide for more carb consistency than others? – via AAEP Ask the Vet

I love the new term you’ve coined: “carb consistency!” It seems like we’re learning more and more about carbohydrates and how horses handle them every day, so right now yes, controlling sugars and starches is kind of a big deal. In addition to horses with equine metabolic syndrome (EMS), polysaccharide story myopathy (PSSM), and laminitis needing lower levels of simple or non-structural carbohydrates (sugars and starches), add to this list horses with gastric ulcers, horses with hindgut acidosis, and horses who simply get too “hot” behavior-wise on high sugar/starch feeds. Does this mean every single horse needs a low-carb diet? No, plus I’m not a fan of the term “low-carb” for horses, as they require a minimum 1% (preferably 2%) of their body weight each day in high-quality forage which is primarily complex or structural carbohydrates. But it does mean owners need to figure out if their horses are in one of these high-risk groups then feed appropriately.

Many horses do quite well on a hay-only diet with a multi-vitamin/mineral supplement or ration balancer to help meet all their protein, vitamin and mineral needs. It gets tricky, though, when a horse’s nutritional needs aren’t met by forage alone, such as a horse in heavy work or as you mention, a malnourished horse. Dr. Carolyn Stull from the University of California-Davis has done some excellent research on bringing the starved horse back to health, which includes dealing with “refeeding syndrome.” Basically, emaciated horses shouldn’t be fed concentrates with lots of simple carbs, nor should they be fed bulky hays or straws with little nutritional value. She found the best way to recover a horse with an extremely low body condition score was to feed small amounts of alfalfa hay every few hours, gradually working up to larger amounts over longer intervals. She doesn’t recommend traditional grain for the super skinny, rescue-type horses for many months.

So while there’s no blanket recommendation about avoiding simple carbs in all horses, definitely speak to your veterinarian about your horses, their medical conditions, and the best way to feed them.