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  • Q:

    My pony (330 lb or 150 kg) was diagnosed with hyperparathyroidism. He is thin with swollen facial bones. To counteract this, I recently changed his to diet to 8 lb (3.6 kg) of feed daily, which includes alfalfa pellets, senior grain, and corn oil. I need to feed calcium-rich feeds, according to my vet. Do you have other suggestions?

  • A:

    In short, nutritional secondary hyperparathyroidism, also known as big head disease, results from the consumption of diets too high in phosphorus and too low in calcium. The disease is not seen as frequently as it once was, due in large part to the introduction of well-fortified feeds into the marketplace. Another cause of hyperparathyroidism is the consumption of oxalate-rich pasture plants; oxalates bind dietary calcium, thereby creating calcium oxalate, which horses cannot use to fulfil calcium needs.

    Regardless of the pony’s nutritional history, based on the new diet you provided, it seems as though you are taking the appropriate steps to resolve the calcium and phosphorus imbalance with a calcium-rich forage product and a fortified concentrate. You may consider switching from a senior feed to performance feed, as generally senior feeds have higher feeding rates, which means more will have to be fed to ensure adequate vitamin and mineral intake. Most performance feeds have a minimum daily intake of 5-6 lb (2.3-2.7 kg); if your pony is not receiving the manufacturer’s recommended minimum, be sure to add an appropriate balancer pellet or vitamin/mineral supplement to round out fortification.

    You may consider adding a calcium carbonate (limestone) supplement to the diet, as it is a good source of calcium and contains no phosphorus. Limestone may decrease the palatability of the meal somewhat, so a bit of molasses will boost palatability.

    For horses living on pasture or consuming only grass hay, we recommend having soil and grass hay tested to gain a better understanding of their nutrient content. However, this current diet of alfalfa hay and little to no pasture probably doesn’t warrant testing.

    For weight gain, you can try to slowly increase the amount of alfalfa and add a third meal daily to increase calorie intake. Three meals will also keep him from going for long periods with an empty stomach between meals. When a stomach is empty for long periods, normal gastric acid can begin to irritate the stomach lining, eventually causing ulcers. Providing small frequent meals is best for digestive health.

    These are general nutritional considerations for your pony. A detailed evaluation of the diet would have to be made before specific recommendations, including supplement choices, could be provided.

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