not-yet-known not-yet-known not-yet-known unknown This commentary presents information about paraneoplastic phenomena, with emphasis on paraneoplastic pruritus and its pathophysiology in the equine species. Pruritus that results from the development of underlying malignancy is often overlooked during the diagnostic and therapeutic management of affected equids. Unexplained pruritus should warrant consideration of a cancer diagnosis and, when appropriate, lead to expanded diagnostic testing in candidate patients. Earlier recognition of underlying cancer may lead to improved treatment outcomes or, in some cases, better welfare outcomes (euthanasia). The emerging role of interleukin-31 as a principal mediator of itchiness (regardless of underlying aetiology) is leading to new research, with an eye to the availability of novel treatment approaches.

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 localize. Identification of surgical targets using ultrasonography and/or Technetium-99m sestimibi scintigraphy are useful for this purpose in both the human and equine contexts. However, these localization approaches are not aways effective. Moreover, not all patients are candidates for general anesthesia and surgery and the costs associated with diagnostic localization 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.