Mudlark, I was listening to the BBC's tame doctor, Dr. Mark Porter, on Radio 2 the other day (this is UK radio BTW). Someone had phoned in asking why, if homeopathy/acupuncture/magnetic wotsits/etc are all placebos, do these things all show some response in animals? since animals obviously can't be made to "believe in" something.

The reply was surprising. According to Mark Porter, animals show an even greater placebo effect than humans do. So what they "believe in" isn't a specific therapy, it's more the fact that a kind human is doing things.

Graham.