Hyperthyroidism, also referred to as thyrotoxicosis is common in older cats (more than 7 years old) . It occurs when thyroid glands (located in the neck) become overactive and start producing thyroid hormones in excess.
Hyperthyroidism in cats is most often caused by a benign (non-cancerous) tumour called 'nodular hyperplasia'. Cats have two thyroid glands, and it is common that both glands may be affected and become enlarged. It is very rare that the tumour may be malignant (adenocarcinoma).
Thyroid hormones regulate many body processes and when produced in excess, have dramatic consequences. Signs of hyperthyroidism include:
Hyperthyroidism can have serious consequences on blood pressure, causing hypertension and damage to the muscular wall of the heart (because of increased heart rate and stronger contractions of the heart wall, the left ventricle can thicken and get bigger), possibly leading to heart disease and even heart failure.
Fortunately, the vast majority of cats that develop hyperthyroidism can be treated very successfully and most cats will make a complete recovery.
Hyperthyroidism in cats is most often caused by a benign (non-cancerous) tumour called 'nodular hyperplasia'. Cats have two thyroid glands, and it is common that both glands may be affected and become enlarged. It is very rare that the tumour may be malignant (adenocarcinoma).
Thyroid hormones regulate many body processes and when produced in excess, have dramatic consequences. Signs of hyperthyroidism include:
- Weight loss as the metabolic rate accelerates and energy is burnt faster
- Usually a good or increased appetite (polyphagia) for the same reason as above.
- Increased thirst (polydipsia)
- Increased activity, restlessness or irritability
- An increased heart rate (tachycardia)
- A poor and unkempt hair coat
- Intolerance to heat
- Panting
Hyperthyroidism can have serious consequences on blood pressure, causing hypertension and damage to the muscular wall of the heart (because of increased heart rate and stronger contractions of the heart wall, the left ventricle can thicken and get bigger), possibly leading to heart disease and even heart failure.
Fortunately, the vast majority of cats that develop hyperthyroidism can be treated very successfully and most cats will make a complete recovery.