It could mean that your cat was constipated and has been straining to poop, or it could signal something more serious. Blood in stool is a sign of some illnesses, so you should take the cat to the vet to be checked out.
The cat may have an infection in its intestines or colon and may need medical attention. It may also be the result of a large bowel movement or the passage of some irritant through the rectum.
It may be something as severe as worms, to something as simple as the food they eat. Try feeding your cats natural cat food without fillers to keep cats healthy.
