• parathyroid adenoma;
  • parathyroid hyperplasia;
  • ultrasonography;
  • canine species;
  • dog

Two hyperplastic parathyroid glands and three solitary parathyroid adenomas were identified using high-resolution ultrasonography in five adult dogs with persistent hypercalcemia. Ultrasonographic features of parathyroid adenomas included visualization of a round or oval, 5 mm or larger, hypoechoic mass in the cranial pole of one thyroid lobe. Each mass had well-defined margins between the thyroid gland and parathyroid adenoma, reduced echogenicity of the adenoma compared to surrounding thyroid parenchyma, and distal enhancement. Ultrasonographic features of the hyperplastic parathyroid glands included hypoechogenicity, compared to surrounding thyroid parenchyma, and a size of approximately 2 mm. Hyperplastic parathyroids were well marginated in one dog and poorly marginated in another dog.