"Sadie-Mae", a 10 year-old spayed female mixed breed dog, presented to the Small Animal Medicine Service for inappetance, lethargy, weight loss, incontinence, occasional constipation and questionable polyuria. Physical exam was unremarkable except for some mild hepatomegaly and slightly enlarged popliteal lymph nodes bilaterally. A complete blood count was within normal limits. A serum chemistry profile indicated a mild hypomagnesemia and a marked hypercalcemia. A parathyroid panel revealed a mildly elevated intact PTH level, a marked elevation in ionized calcium and a PTHrP level that was within normal limits. Cervical ultrasound revealed a small, focal, round-oval hypoechoic nodule in the thyroid tissue on the right side. These results suggested a diagnosis of primary hyperparathyroidism. Sadie-Mae's owners opted to pursue therapy using ultrasound-guided percutaneous ethanol injection to the chemically ablate the affected parathyroid gland.