Here are some general points about allergies you should be aware of:
1) Allergies are cumulative. In other words, a pet may have both food and environmental allergies but the symptoms only become noticeable during certain times of the year. This doesn't mean your pet doesn't have allergic reactions all the time. It just means that the situation builds up similar to a balloon that fills up with air until it pops. In your pet's case, it may mean that all of a sudden your pet has hot spots or starts chewing on its paws or rear end during the hot summer months but most likely has underlying digestive issues all year round.
2) Cats and dogs may display allergy symptoms differently. Cats may have respiratory symptoms, vomiting and other digestive disorders due to allergies as well as skin reactions. Dogs may have scratching, itching, chewing on fur, ear infections, scooting on their rear end and weepy eyes.
3) Most of the time, pets have BOTH food and environmental allergies. There is no one medication or supplement that will cure your pet’s symptoms. Skin problems are tough and require a comprehensive effort.