The purpose of this study is to learn more about the causes and treatment of feline interstitial cystitis (FIC). This syndrome is the most common cause of lower urinary tract signs in domestic cats, occurring in approximately 1% of owned cats. The signs of FIC include pain, bloody urine, and urinating outside the litter box. Millions of cats are euthanized as a result of this disease, making it a major veterinary problem and feline welfare issue. The researcher’s laboratory has identified problems with normal function of the adrenal gland, an important source of many hormones. These problems may play an important role in the causes of and treatment of these cats with FIC. Based on earlier studies, the researchers will compare hormone concentrations in 32 neutered healthy and FIC cats of both sexes. The data will be used to design hormone replacement therapy to test the effects of hormone replacement on the signs of the disease. It is hoped that replacement therapy will result in clinically important improvements in the cats’ symptoms.