I need some help pretty quick. A neighbour's cat that hangs around the house a lot has fallen ill and seems to be getting worse rather quickly. Right now he's drooling excessively and can't quite balance himself on his legs. No obvious signs of injury and at first glance doesn't seem to be in any distress, but I know something is not right. Earlier in the day he was drooling a lot, but he could still walk and keep his balance. His breathing at the moment seems to be ok. Any ideas what's wrong with him?