Hi Margaret-
How old is your cat and how long has he had loose stool? Is the food you feed listed on the recall list anywhere?
http://www.fda.gov/oc/opacom/hottopics/petfood.html
Loose stool is almost always tied into either parasites or a problem with the food. I would take a stool sample into the vet and let them check for worms, coccidia and giardia. All of these things are easy to treat with medication. These things are the most common cause of loose stool in a cat, unless your kitty has developed irritable bowel or an allergy to his food. Given his age, it would be unlikely that either of these are the problem, and I would start with the more obvious, easily treatable possibilities.
Please let me know if I can help you further.
Feline Healthcare
16 yrs health care mgmt & issues relating to cats, reproductive issues and multicat environments