Owners get discouraged, and skeptic,when dogs throw up right after their meals, or getting diarrhea after their new diet.
I am posting here my experience, and handling of this type situation; or what I would do if it be my dog having this type of a rejection.
In the years of my raw meat serving, I experienced never food intolerance; neither in older dogs, I had when I started, nor in the puppies I reared on raw food.
Small amounts is the key to get his gut to develop the needed enzymes .
Small is the key to all feeding, especially concerning small dogs, and toy breeds. Too big amounts per meal will just bring tummy upsets = diarrhea.
Small amounts, multiple times per day if needed.
I am feeding basically 2-3 oz per meal per Papillon twice/day.
Those are mini amounts, especially if I add to each one serving several items.
My Papillons don't get to eat one egg, or all 3 oz just turkey, or beef. No, I give them 2-4 items each meal into the bowl, and now you are talking about tea-, or table spoon sizes of something.
If my dog still would have diarrhea, or throw up, I would stepp back even further, and give lesser, more often. As much as 3-5 times/day micro amounts of food. A tiny bit of Greek Yogurt also aids to set the gut right, and helps digestion.
Dogs/Wolfes by nature eat many things, and many rotten things even. There is rarely a dog being truly "allergic" or intolerant to any food .
So, please do not get discouraged, and give up. Do not think too quickly of allergy, or intolerance, rather think "small".
Home made bone broth is also a great add to your pet's food a few times / week. Home made, from real bones/meat is the key here, as store -bought broth is not of recommended quality (read the label, and you will see).