Personally, I am sure I am allergic to anything green. When I see string beans or broccoli I start to feel sick. My solution is to just ignore them and leave them in my dinner bowl but for others who might be having an allergic reaction, Percy and I think it is best to see your vet.
Pets’ allergies most commonly arise from allergens, such as pollen, mold spores, house dust, and mites. Remember those “dust balls” we are accused of creating? Bad stuff can hide in them. Although any dog can develop allergies Percy tells me there are no particular cat breeds that appear to have a predisposition to allergens. Typical.
In addition to environmental allergens, allergic reactions in animals may be caused by food allergies, fungi, and parasites, such as fleas and mites. Hate them all. Some allergies are easy to treat and some not so easy. The best plan is to work with your vet to come up with a plan. Good luck.