Ya, it depends on the dog really and it can take some trial and error to find a food that they like and works for them. My Alice (I learned last week
) gets loose and even runny poops from too much red meat, so no beef or venison for her.
How was the poop when you got him? If he was only on a raw meat diet at the breeder's and the food you're trying now all have grains in them, could be he can't handle grains. There are alot of great kibbles that are grain-free (since you're in the UK, not sure what brand to tell you, you'll have to see what you can get). The other thing you can use (if he did well on raw at the breeder's), if you're willing, is pre-packaged raw pet food. You buy and store it frozen and it only looks like a hamburger patty, so it's not gross (I personaly think canned dog food is way more gross lol
).
You may want to give his tummy a break for a few days first though by feeding a bland diet before trying the grain-free or pre-made raw - boil white rice with 4x the normal amount of water and let it simmer for about 30 minutes (it will get really mushy). Mix that with some boiled chicken breast and a bit of canned pumpkin (UNspiced). i'd do that for a few days, then try the next food and since he was on chicken before - look for a grain free food with chicken as the main protein course.
Good luck
