Hyperthyroidism is a common endocrine condition that affects predominantly older cats. It is more common in female cats than male cats, however it can occur at any age. It can develop and progress slowly over several months. The thyroid gland is located around the airway midway up the neck. Thyroid hormone (T3 & T4) is involved in many metabolic processes such as heart rate, blood pressure, sleep-wake cycle, energy metabolism, fat storage and mobilisation, and thermoregulation.
Excess thyroid hormone production is often due to tumour development within the thyroid gland. These tumours are considered “active” and produce thyroid hormone without regulation. Some tumours are active but benign, meaning they don’t spread to other parts of the body, while others are considered active and malignant.