Primary hyperparathyroidism results from autonomous secretion of parathyroid hormone by a single or multiple parathyroid glands. Clinical signs result from various combinations of hypercalcemia, hypercalcemic nephropathy, urolithiasis, or mobilization of calcium and phosphorus from bone. Following parathyroidectomy, the prognosis for dogs with primary hyperparathyroidism is good if the disorder is diagnosed before renal disease is advanced.