My Max had a bout of it about 3 years ago and we almost lost him. Not only did he have blood in the stool, he was vomiting blood. They think part of his had to do with all the steroids he had been given for his allergies. We put him in the emergency hospital for 24 hours and our vet's office for another 12 hours. I can't remember what all they gave him, but he did pull through it. It's pretty scary stuff.