The weight loss may be so gradual that some owners will not even realize it has occurred or it may be quite rapid. Affected cats often drink a lot of water and frequently urinate. There may be periodic vomiting or diarrhea , and the hair coat may be unkempt. In some cats, anorexia develops as the disease progresses. Two secondary complications of this disease can be significant.
Hypertension develops as a consequence of the increased pumping pressure of the heart.
In some cats, blood pressure can become so high that retinal hemorrhage or detachment will occur and result in blindness. Heart problems develop because the heart must enlarge and thicken to meet the increased metabolic demands. Both of these problems are reversible with appropriate treatment of the disease. Some of the risk factors for hyperthyroidism have been defined above. A specific cause has not been identified.