A six year old male castrated Keeshond was presented for evaluation and treatment of primary hyperparathyroidism after testing positive for the gene associated with this disease. Ionized calcium measurements and a parathyroid panel were consistent with primary hyperparathyroidism. Additional diagnostics, including thoracic radiographs and an abdominal and cervical ultrasound were performed to confirm a diagnosis of primary hyperparathyroidism and to rule-out other causes of hypercalcemia. This report describes the pathogenesis, clinical signs, diagnosis, treatment, and prognosis for this disease, and the genetic basis of primary hyperparathyroidism in Keeshonden.