The proteins of domestic animals and pets are among the most potent allergens in closed spaces.

There are two types of allergic reactions to animals:

			Cutaneous: these reactions are caused by cat allergens, and are characterised by localised facial reactions with swelling of the eyelids and reddening of the entire face, with or without associated urticaria.
			Respiratory: such reactions can range from simple rhinitis (mucous secretions, sneezing or nose itching) to severe asthma (breathing difficulties, cough or wheezing).