If a cat has blood in its urine without treatment and the condition is serious, it will die in about one to two weeks, because blood in its urine will make the cat mentally ill, lose its appetite, become weak, etc., and over time it will be life-threatening. The cause of blood in the urine of cats may be urinary tract infection, urinary tract blockage or urinary stones. It is best to go to the hospital for timely examination and treatment. Usually, cats should drink plenty of water, keep the environment clean and hygienic, and eat mainly light meals.