Postoperative recurrence of feline primary hyperparathyroidism (parathyromatosis)

Abstract This report describes a case of suspected feline parathyromatosis, a rare condition defined as the development of new hyperfunctional parathyroid tissue in the neck, typically resulting from seeding during previous parathyroid surgery. A 14‐year‐old domestic shorthair cat was diagnosed with a left parathyroid adenoma after presenting with polyuria, polydipsia, constipation and hypercalcaemia. Thyro‐parathyroidectomy was performed, and ionised calcium levels normalised. Two years later, the cat developed recurrent hypercalcaemia with elevated parathyroid hormone. Physical examination was unremarkable, with no palpable mass on the neck. Ultrasonography of the abdomen and cervical region, along with thoracic radiography, yielded insignificant findings, and the cat was managed medically. Three months later, a palpable nodule was identified in the left subcutaneous cervical region and surgically excised. Histopathology confirmed the recurrence of parathyroid adenoma. Postoperatively, the ionised calcium levels normalised. The cat later developed acute‐on‐chronic kidney disease and was euthanased due to poor response to treatment.