C-cell tumours of the thyroid in the horse.

This study details the clinical and pathological observations of two cases of C-cell tumours in the thyroid of a horse and a pony, both of which presented with an enlarged paralaryngeal mass and frequent gulping. Post-surgical examinations showed C-cells with secretory granules. Remarkably, both equines have shown considerable recovery: the pony being healthy three years post-surgery and the horse resuming successful racing after the tumour was removed.

Objective of the Research

• The research aimed to explore the clinical manifestations, pathological aspects, and post-operative prognosis of C-cell tumours in the thyroid glands of equines. These are unusual types of tumours that affect parafollicular cells (or C-cells) in the thyroid gland.

Case Details and Clinical Observations

• The study focused on two cases involving an adult horse and a pony exhibiting similar symptoms. Both showed an abnormal enlargement in their paralaryngeal region and a constant gulping behavior.
• The abnormality was determined to be a tumour in the thyroid gland, which was surgically removed in both cases.

Pathological Aspects

• Upon ultrastructural examination of the surgically removed tumours, it was found that they were primarily composed of C-cells. These cells are responsible for the production of calcitonin, a hormone that helps regulate calcium and phosphorous levels in the body.
• Notably, the C-cells in these tumours contained typical membrane-bound secretory granules, indicating that these cells could still function and produce hormones.

Post-Surgical Prognosis

• Both the horse and pony were monitored following the surgical removal of the tumours.
• The pony remained alive and well three years after the surgery, implying long-term positive outcomes in such cases.
• The horse, not only survived but also returned to competitive racing successfully, indicating that this type of tumour and its surgical removal does not cause significant long-term damage to an equine’s vitality or physical capabilities.