For a discussion of developmental diseases of the mouth, see Congenital and Inherited Anomalies of the Digestive System: Congenital and Inherited Anomalies of the Mouth. For eosinophilic granuloma complex, see Eosinophilic Granuloma Complex.

The primary and most important function of the mouth is to obtain and introduce food into the digestive tract. Additional functions include communication and social interaction, grooming, protection, heat regulation (particularly in dogs), and grasping objects. The latter is very important for performance animals (eg, Retrievers, military and police dogs). Similar to other areas of alimentary tract, the oral cavity in the normal healthy state supports a large and diverse population of bacteria that lives primarily in biofilm communities. Unlike other areas of the body, the mouth also contains nonvital surfaces (enamel of teeth) that have neither local immune system defenses nor the ability to regenerate their surface through cellular replacement. The gingiva and mucosa have an excellent vascular supply, and the tightly adherent gingiva protects the underlying bone from trauma, thermal injury, and bacterial invasion.

Food prehension requires a complex interaction of the muscles of mastication, the teeth, the tongue, and the pharyngeal muscles. When any of these become compromised through disease or trauma, malnutrition and dehydration may result.

A complete oral examination should be included in every physical examination because oral diseases are most effectively treated when diagnosed early. Unfortunately, many problems remain hidden in the mouth until they have progressed to an advanced stage.

Last full review/revision March 2012 by Gregg A. DuPont, DVM, Fellow AVD, DAVDC