Blood in feline urine can be a sign of a condition called hematuria in young cats, while it is sometimes a sign of cancer in older cats, states petMD. Bloody urine can also be a sign that the cat has feline lower urinary tract disease, states WebMD.
Some of the causes of hematuria in cats include blood clotting, a low number of platelets in the blood, inflammation of the blood vessels and cystic kidney disease, according to petMD. A cat may develop a urinary tract disease because of bladder infection, a plug in the urethra, a weak bladder or too much stress, states WebMD. This problem is more common in male cats around the age of four.