Should I call the RSPCA?

If they're at least fed and walked I'm sure their owners do care. It's kind of based on if they're aloud in the house at night or not. But there's no harm whatsoever calling them if you have concerns they'll decide if it's wrong or not. If it's not then I doubt they'd mind that you are worried I think you should because there's no going wrong really is there? I think it's great you're bothered about animals well being.