What are the tumors of the thyroid?
Thyroid tumors include cystic structures called goitres, multinodular overgrowth (hyperplasia), benign (non-spreading) cancers (adenomas) and malignant (spreading) cancers (carcinomas). Hyperplasias and adenomas grade into each other and most produce excessive quantities of thyroid hormones. These induce complex clinical syndromes. Malignant thyroid tumors rarely produce hormones but they may spread both locally and to the lungs. Up to a third of thyroid carcinomas in dogs may originate from specific cells in the thyroid glands (C-cells) that act in combination with the hormones of the parathyroid glands to regulate blood calcium. What do we know about the cause? The reason why a particular pet may develop this, or any cancer, is not straightforward. Cancer is often seemingly the culmination of a series of circumstances that come together for the unfortunate individual. One non-cancerous tumor of the thyroid called ’colloid goitre’ is due to inactivity of the gland. This is often cause
