Question
I have an overweight 27-year-old Tennessee Walking Horse mare with insulin dysregulation and PPID. She is currently battling laminitis, the first bout of which occurred last fall. For years her diet consisted of pasture grass, alfalfa hay when needed, beet pulp, and a small amount of a low-starch feed. She lives outside, so after the fall episode we thought it best to put her in a drylot this spring. However, she had a laminitic flare-up when we took her off of grass. Recent bloodwork revealed exceedingly high baseline insulin levels. Now that she is in a drylot, she gets alfalfa hay morning and night along with grass hay at other times. She is still eating 0.75 lb (0.3 kg) of low-starch feed and a handful of beet pulp (rinsed with no molasses). I have heard good things about flax meal, so I added 4 oz (113 g) daily. We are growing grass hay to replace the alfalfa completely. Her weight appears to be moderate—I can still see ribs somewhat—but she still has visible fat pads and a slight cresty neck. What else can I do for this mare?
Answer
Without knowing the current hay intake, it sounds like she would benefit from a restricted diet consisting of approximately 1.5% of body weight per day in hay. When feeding only 1.5% of body weight per day (for your mare, that would be 14 lb or 6.4 kg), it is important to use a slow feeder or divide the forage into frequent, small meals so that prolonged fasting is avoided. Offering restricted amounts of hay requires careful weighing to ensure she is not eating too much or too little. All diet changes, including swapping forages, should be done gradually. I suspect the stress of transitioning to a drylot, coupled with the change to an alfalfa-based diet, played a role in the episode of laminitis in the spring.
General guidelines for feeding metabolic horses include offering forages that contain 10-12% NSC (nonstructural carbohydrates = starch + water-soluble carbohydrates). However, severity of insulin dysregulation observed in some horses may require even lower starch and sugar intake to support optimal health. I imagine your mare may fall into this category given the recent test results.
A value for water-soluble carbohydrates is not listed on the forage analysis you provided, and this is a key factor in determining NSC content. When the NSC is unknown, hay can be soaked in cold water for 60 minutes or hot water for 30 minutes prior to feeding to lower water-soluble carbohydrates. Hay that is lower in energy (calories) and high in fiber is desirable for metabolic horses. Transitioning your mare to grass hay and eliminating or significantly reducing the alfalfa hay is also recommended, and I know you’re working to this end.
Although the current feed is low in NSC and fed in a small amount, it is not contributing to her nutrient intake and is therefore unnecessary. If you would like to keep rinsed beet pulp in the diet to serve as a base for mixing supplements, that should not cause any problem. A good way to ensure she is consuming the vitamins and minerals needed for optimal health, without increasing energy, is by adding a balancer pellet or a concentrated micronutrient supplement. In this situation, a balancer pellet might be preferred, as these products generally include high-quality protein. Horses with PPID sometimes have muscle wasting, and the additional protein will be beneficial.
Although micronutrient supplements often contain vitamin E, horses that do not consume fresh grass and those with suppressed immune systems (PPID) benefit from added vitamin E supplementation. Natural-source vitamin E is the best form to provide. Nano-E is a water-soluble natural-source vitamin E supplement that is rapidly absorbed into the bloodstream that provides body-wide antioxidant protection.
Targeting inflammation through omega-3 fatty acid supplementation is recommended for horses with metabolic conditions and laminitis. Research has shown that certain omega-3 fatty acids—specifically DHA and EPA—are more effectively incorporated into the horse’s red blood cell membranes than plant-derived omega-3 sources, such as those found in flax byproducts. EO-3 contains a concentrated source of DHA and EPA in a palatable mint-apple flavor. Because of its low feeding rate, it is not considered a significant calorie source.
The dietary changes you’ve implemented for your mare are on the right track. Once you receive more information about the nutrient content of the hay, these recommendations may change slightly. After any lameness has disappeared, introducing more movement and exercise would be ideal, though consultation with a veterinarian on this point is recommended.
Also noteworthy: I’d suggest regular body condition scoring. Because maintaining metabolic horses can be tricky at times, it is possible to go too far in trying to reduce weight and rid them entirely of fat pads and cresty neck. In some cases, the horses often lose more body fat over the ribs and topline, and do not lose the pads or crest. They can have a body condition score of 3 or 4 and still maintain some regional adiposity.
