Urine, produced by the kidneys, is stored in the urinary bladder before exiting the body through the urethra. The urethra acts as a channel for urine excretion; its length offers protection against infection from the outside. Cats with urinary bladder inflammation (cystitis) strain to produce small amounts of urine (may appear as constipation), urinate outside the litter box, and may have blood in their urine. Common causes of urinary bladder inflammation include feline idiopathic interstitial cystitis and stones. Urinary tract infections affect cats less commonly due to their highly concentrated urine. An inability to urinate (straining with no urine production) requires emergency treatment to relieve the painful, life threatening obstruction.