Which proteins are most likely to cause food allergies in dogs?

The proteins that top the list are the ones dogs eat most. Beef and dairy are the usual front-runners, followed by chicken, then wheat, egg, lamb and soy. Beef and chicken turn up again and again in studies, which surprises people because they're in so many everyday foods. That's exactly the point, though. Dogs don't react to a protein they've never met. Allergies build through repeated exposure, so the 'most allergenic' proteins are really just the most commonly fed ones.

Two things follow from that. A food can be perfectly good and still not suit your particular dog, if their immune system has decided it doesn't like chicken. And a dog can happily eat something for years, then start reacting to it, which throws a lot of owners because the food didn't change. The dog did.

This is also why vets often reach for a 'novel protein', one your dog hasn't had before, when they're working out a suspected food allergy. Venison, rabbit or duck are less likely to cause a reaction because they're unfamiliar to most dogs. Lamb sits a bit lower on the common-allergen list too, which is part of why it's a popular switch for dogs raised on chicken or beef, and why we build Happy Hour around NZ grass-fed lamb. If you think food's behind your dog's symptoms, talk to your vet before you start swapping proteins, because a proper food trial has to be planned to tell you anything useful.