Blood ON faeces

The last few days there has been a trace of blood on the top of Molly's poo. We asked the vet what could it be when she went for her vaccinations on Friday, and the vet said as long as it's only on top and doesn't go on too long it probably means she's passed a large movement and damaged her colon, which should pass. That doesn't stop me worrying though!

We had a cat that had that problem every now and then his whole life.  Nothing ever came of it.  It usually means just a little irritation close to the rectum.  Happens in people, too.  Don't ask me how I know!

If it's bright red, and I'm sure it is, since you noticed it, the problem is very close to the opening.  It sounds like your vet is on top of it, but if it changes, call him again.