Q: My 25-year-old gelding has pituitary pars intermedia dysfunction (PPID, formerly known as equine Cushing’s disease) and a history of laminitis. During the winter he struggles to maintain a healthy weight. I’m worried about feeding him too much due to his PPID and laminitis history, but it can be hard to help him maintain his condition through the colder months without additional feed. What can I do to help him maintain a healthy body condition score (BCS) during winter without putting him at risk of another laminitic episode?

A: When managing horses with PPID, it is important to monitor their weight consistently. It is great that you are proactive, looking at what you can implement to support your gelding before the cold weather arrives. Caring for these horses successfully depends on managing their nutritional and medical needs effectively.

Horses with PPID commonly struggle to maintain a healthy body condition, and they frequently struggle to sustain their muscle tissue. When a horse is underconditioned, it can be tempting to add extra commercial feed to his program. Be very cautious doing this, however, because PPID horses are at a greater risk of developing the painful hoof disease laminitis and are sensitive to starch and sugar in the diet.

Due to your gelding’s health and his history with endocrinopathic laminitis, you should most likely maintain him on a diet low in both starch and sugar but that still provides adequate calories.

Starch and Sugar in Horse Diets

The carbohydrates starch and sugar can be either hydrolysable or fermentable, depending on if the horse can break them down enzymatically. If not, the horse ferments them in the hindgut. The general rule of thumb for feeding horses with metabolic issues is to ensure that hydrolyzable carbohydrates (HC) make up no more than 10% of their diets.

If your gelding can still chew and consume hay properly, offering free-choice hay with less than 10% HC could help him maintain his weight during winter. Before feeding new hay to your horse, always have it analyzed. You cannot accurately estimate hay’s sugar content by looking at it, so untested hay can be risky for horses with metabolic issues. 

Along with hay, provide your horse a high-quality ration balancer, low in starch and sugar, at the recommended rate for his weight to ensure he gets the necessary vitamins and minerals daily.

Adding Calories to a Metabolic Horse’s Diet

To supplement his daily ration with additional calories, offer products such as forage pellets or cubes, unmolassed beet pulp, fat sources such as ground flax or oil, and low-sugar commercial feeds.

Occasionally, hay low in starch and sugar is overly mature and, therefore, provides less calories. In these cases you can offer soaked fiber sources such as hay cubes or beet pulp, which are highly digestible, for additional calories. Typically, older horses have an easier time chewing these.

Owners can also use oils and fats for horses with metabolic issues. These products are calorically dense but not digested the same way as carbohydrates and do not impact blood insulin. Introduce fats slowly because horses do not have a gallbladder (which stores and concentrates bile that aids in the digestion of fat). Camelina, flax, hemp, and ahiflower oil are all great examples of fat sources that can be added to increase your gelding’s calorie intake safely. You can also use powdered fat supplements available on the market.

Take-Home Message

Adding calories to a metabolic horse’s diet without risking a laminitic episode can be challenging. Always begin by ensuring you’re meeting your horse’s base nutrient requirements with a safe hay and high-quality ration balancer. From that point, consider using soaked fiber sources and fat to provide additional calories.