my dog has loose stool

Question
I recently changed my 12 month puppy from puppy food chicken and rice to adult dog food lamb and rice since my older dog eats that kind.(Nutros)
My puppy since then has loose stool....I dont know if I should wait for a few days to see if his stomach get used to the food or I should change him to the same type he had before but for adult.

Answer
Any sudden change in diet can lead to loose stools.  If he doesn't firm up before long try a bland diet.  

If a dog is having trouble keeping anything down or continuing diarrhea try this out of the manual I have from a large, knowledgeable dog guide school.

Bland recovery diet for dogs.

3 parts cooked rice, one part boiled hamburger or chicken, or cottage cheese. I think you can substitute boiled potatoes for the rice. Once in an emergency, we bought a plain baked potato from Wendy's.

This is meant for short time settling a dog's digestive tract. It is not the complete and balanced diet they need long term. I have seen it work.