I think Orijen is one of THE best, so soundly based in science - I love their white paper about nutrition.
Since it is a high protein food, your dog is probably needing more water - hence the drinking more and perhaps drinking a bit too much, making the tummy upset. But, since you started 2 new things at one, it could from the Dentatreat as well.
If it were me, I'd probably hold off on the Dentatreat, feed the Orijen, maybe sprinkle some water on the Orijen (or add in a bit of canned for moisture) - and see how he does on that. If tummy does okay, then I'd maybe try the Dentatreat...
Welcome to YT!!
