Wound licking is an instinctive response in humans and many other animals to lick an injury. Dogs, cats, small rodents and primates all lick wounds. Saliva contains tissue factor which promotes the blood clotting mechanism. The enzyme lysozyme is found in many tissues and is known to attack the cell walls of many gram-positive bacteria, aiding in defense against infection. Tears are also beneficial to wounds due to the lysozyme enzyme.