Blood in Stool

I woke up this morning and went to the bathroom to discover, Miki had been shut in the bathroom all night. Being a quiet cat, she never let me know. Well of course, when a cat has to go, they go, no matter if there is litterbox in sight or not. She had gone poo in the corner and when I went to pick it up with tissue, I noticed a yellowish substance clinging to one of the poos that had blood in it. Any idea what this could be? I called my grandmother and asked her and she said Miki probably ate something that scratched her insides. Miki does tend to chew on cardboard, but I'm not sure if that would cause her to bleed. Any ideas, suggestions, opinions?

If there is blood in the stool, I would certainly at least telephone my vet to see what they had to say.

Did you save the stool sample?

does anyone know what it maens when there is blood in the urine? Im thinking it is crystalization of the urine...but Im not one hundered percent sure. I have a male cat and he has been doing it all night and has continued this morning, unfortunitly it's still to early to contact the vet.

Her behavior hasn't changed. She eats and drinks fine. There wasn't a lot of blood in it, like a little streak. I don't have a sample.