Hyperthyroidism is a disorder characterized by the overproduction of thyroid hormone. When excessive amounts of thyroid hormone are in the circulation, the body's metabolism speeds up greatly. Many organs are affected by this disease, including the heart. The heart is stimulated to pump faster and more forcefully, much like hypertrophic cardiomyopathy. This results in a greater output of blood and high blood pressure.
Hyperthyroidism is a fairly common disease of older cats.
If any of these are diagnosed, the cat's blood pressure will be checked, if the equipment is available. If a sudden onset of blindness occurs and the blood pressure is found to be abnormally high, the other conditions are considered as possible underlying causes. Blood pressure is determined with a device that can detect blood flow in arteries. However, the cat has very small arteries compared to humans. Therefore, the standard blood pressure equipment used on humans will not work on cats.