Millys mum, she is only on between 30 -40g of the dry a day, split into 2 meals, morning and night. She has been tested for Giardia and the other things you mentioned, all negative, and has been on the metronidazole anyway as a just in case measure, but is now on it for the IBS anyway! When trying a new food it has depended on how severe the diarrhoea has been with it. Some of them have just caused a constant running to the litter tray every 5 mins, while others have left her severley incontinent and doing her business everywhere. She has been at deaths door a few times because of it, and obviously she couldn't be kept on foods she cant tolerate. The only thing she has ever been able to take on its own was the plain white fish, but obviously not great long term health wise as there wasn't enough nutrients in it for a little kitten. I have considered raw diet, but would have no idea where to get the zinc and other supplements that have to be added to it as I cant shop over the internet. The canikur came from a very kind friend of mine who bought them for Teddie alomg with her dry food, the promax I got from my vet.