The most common type of allergies seen in cats are flea allergies. Since cats are such meticulous groomers, you may not even find fleas present on your cat’s skin. Cats are allergic to the saliva from the flea bite and it just takes one flea bite to send sensitive cats into a biting and scratching frenzy. Other allergies occurring less commonly in cats include inhalant and food allergies. Unlike people, allergies in pets are manifested by changes in the skin.