In order of the most common offenders in dogs are beef, dairy products, chicken, wheat, chicken eggs, corn, and soy. (ohiolabradoodles.com)
Corn, wheat, and soy are some other common offenders. (slumbersounds.com)
Although parents have found milk and gluten to be the most common offenders, it's quite common for various other foods to be problematic for any given child. (babyreference.com)