Dogs and cats are affected by food allergies. Having a pet cat has its rewards and you get to have a companion when you're all alone in you house. But did you know that even if your feline companion is just 5 months old, it can already have a food allergy? However, majority of cats exhibit symptoms of an allergy between 2 to 6 years old. Those cats that have food allergies have contact allergies or concurrent inhalant.