A bloody stool is usually the result of straining when going to the bathroom or minor colon irritation. If a kitten regularly produces a stool with blood, it may be the result of parasitic infection, a virus, cancer or a reaction to something it ate.
The sight of blood when a kitten goes to the bathroom need not be too alarming. It is normal for a cat to occasionally pass a stool with a small amount of blood. It is usually the result of not eating enough fiber and having to strain, or having eaten something that is not completely or easily digestible. This undigested item causes some irritation and bleeding as it passes through the colon.
When a kitten regularly passes stool with blood, has straining or constipation or goes to the bathroom more often than usual, it is time for a visit with the vet. The kitten may be suffering with a viral, bacterial or parasitic infection or have early inflammatory bowel disease. Other less likely causes that should still be checked out include cancer, poisoning, a blood clot disorder or even damage to the bowels. Make an appointment to see the vet as soon as possible. Take along a fresh stool sample to help the vet with identification of the problem.