Food allergies can definitely pop up at any time. Our first Boxer did not exhibit signs of food allergies until he was 6 years old. This was back before I had any clue about nutrition however, and fed him nasty foods. I simply didn't know better...

Once he was really having issues with his allergies I started doing research and learned a lot, changed his diet and supplementation, and it made a huge difference, he was like a new dog. I am also of the school of thought that exposure to many different foods helps lower the likelihood of developing allergies. My present Boxer, who is almost 2 1/2 has been on rotations of foods and different protein sources since he came home with us at 8 weeks. He is incredibly healthy, has great skin and coat, muscle tone, immunity, you name it.