Hormones are chemical signals within the body. They are generally transported in the blood to carry messages from one part of the body to another. Some diseases of the hormonal system are quite common in cats, particularly hyperthyroidism (caused by excessive production of thyroid hormones). Because hormones are carried throughout the body disorders of the hormone system can often have far reaching effects on many different body systems.
Most hormone diseases are treatable - particularly those resulting from a hormone deficiency as this can usually be compensated for by supplementing the animal with the missing hormone. In most cases treatment needs to be lifelong and it often takes a long time to find exactly the right treatment for an individual pet so it is essential that you work closely with your vet in managing hormone problems.