1 INTRODUCTION Primary hyperparathyroidism (PHPT) is a well-recognized cause of hypercalcemia in dogs.1 Despite this, research surrounding PHPT remains contentious.1-15 In PHPT, a hypercalcemic state is produced through the secretion of parathyroid hormone (PTH) by pathologic chief cells (adenoma, hyperplasia, or adenocarcinoma) resulting in stimulation of renal tubular and intestinal calcium resorption and osteoclast-mediated bone resorption.16, 17 Clinical signs of PHPT (polyuria and...