Due to the various effects that thyroid hormones have all around the body, the symptoms of hyperthyroidism can be variable between different cats. However, weight loss (despite an increased appetite) is very common. Other symptoms that are frequently seen such as an increased thirst or diarrhoea can overlap with many other health complaints seen in elderly cats. Hyperthyroidism can also contribute to secondary issues occurring such as high blood pressure, and vision issues and be seen commonly alongside heart conditions like hypertrophic cardiomyopathy (HCM). You should be familiar with the symptoms of hyperthyroidism as this can help you to monitor whether your cat’s condition is improving once treatment has started.