Although it seems as though food allergies in dogs, cats, and other pets are common, the true rate at which they occur is not known. While there may be similar mechanisms behind human and pet food allergies, those in pets have not been studied as much. Better understanding of what causes pet allergies may help researchers design more effective treatments.
Read more about pet food allergies in Mental Floss. The scientific review of the issue is available in the journal Allergy.
An overview of food allergy in animals is also available in the Merck Veterinary Manual.