The overwhelming majority of allergies in dogs is caused by environmental allergens – something your dog is breathing in, such as pollen or dust mites or mold. And sometimes that’s seasonal, so depending on what's pollinating outside, your dog may develop a seasonal, two to three month allergy. I mention this because clients will often come to me with a dog that is showing signs of allergies – the typical itching, foot chewing, or ear scratching – and they automatically assume it's food related, but most of the time the cause is something in the environment.