I don't see grain allergies more prevalent, I just think we're better at diagnosing them. And they really are NOT that common. It is way more common to have an allergy to the protein (meat) component.
I don't see any benefit to grain free unless there is a documented allergy, and then I'd recommend a limited ingredient food avoiding that antigen.
Regarding switching foods: allergies don't seem to be more common with greater volume of one food stuff being fed. The exposure to more antigens (many different foods) increases the chance that you will run across one that stimulates the allergic reaction. That being said, food allergies are relative uncommon in dogs and cats.
I hope we're finding the cause of the cardiomyopathy associated with grain free foods. Until the causal relationship has been verified, I still recommend avoiding grain free foods.
Doug, DVM
