Many dogs are allergic to different substances, including food, and according to veterinarians, seasonal allergies affect dogs much more than food allergies do. Fortunately for dogs suffering from allergies, some allergy relief supplements have all the ingredients necessary to relieve seasonal, skin, environmental and food allergies. Pet experts suggest you look for several ingredients in an allergy supplement, including probiotics, quercetin, omega fatty acids, L-theanine, fish oil, and magnesium among others. Allergy relief supplements are available as both chews and in liquid form. An itchy dog generally isn’t a happy dog. If your dog scratches a lot and there are no fleas present, an allergy supplement might be the ticket to him or her living a longer, happier, healthier life.