As in human, cat allergies are generally unique to each cat. However, there are four main causes for this condition, namely contact, food, flea, and inhalant. A cat sensitive to allergy will get easily contract it when it gets in contact with other animal or even human who had developed the allergy first. If a cat eats the wrong food, for example a diet with too much protein and carbohydrate, it can also get the allergy. Flea and inhalant are the most common and difficult to prevent cause of allergy. The symptoms include itching skin, coughing, sneezing, wheezing, or vomiting or diarrhea.