Primary hyperparathyroidism in horses: What can we learn from human medicine?

Equine primary hyperparathyroidism is rare compared with the condition in human medicine where it is often encountered and represents the most common explanation for hypercalcemia in the outpatient setting. Primary hyperparathyroidism results from a hyperfunctioning parathyroid gland and surgical treatment (parathyroidectomy) is typically curative. Successful surgical removal of a diseased parathyroid gland can be challenging in horses as both normal and hyperfunctioning glands are difficult to localise. Identification of surgical targets using ultrasonography and/or Technetium-99 m sestimibi scintigraphy are useful for this purpose in both the human and equine contexts. However, these localisation approaches are not always effective. Moreover, not all patients are candidates for general anaesthesia and surgery and the costs associated with diagnostic localisation and parathyroidectomy may be prohibitive for some owners. This commentary presents information about primary hyperparathyroidism in the event that it is not treated and strives to review aspects of the disease when left untreated from the human medical context.