Stomatitis is a clinical sign of many diseases in large animals. Oral trauma or contact with chemical irritants (eg, horses that lick at their legs after having been "blistered" with caustic agents) may result in transient stomatitis. Traumatic injury from ingestion of the awns of barley, foxtail, porcupine grass, or spear grass, as well as feeding on plants infested with hairy caterpillars, also will result in stomatitis in horses and cattle.
Clinical signs commonly associated with acute active stomatitis include ptyalism, dysphagia, or resistance to oral examination. Oral examination is facilitated by sedation, after which the mouth can be examined carefully with the aid of a mouth speculum and a light source. Ulcers should be visually and digitally evaluated to determine whether embedded foreign material (eg, grass awns) is present. If the etiology is ingestion of foreign material, changing the quality and quantity of the hay or removing the animal from a pasture with grass awns may effect recovery.
Differential diagnoses include actinobacillosis Actinobacillosis Actinobacillosis is caused by several species of gram-negative coccobacilli of the genus Actinobacillus. Clinical signs vary, depending on the specific bacteria and the animal species... read more 
, foot-and-mouth disease Foot-and-Mouth Disease in Animals Foot-and-mouth disease is one of the world's most economically important viral diseases of livestock. The virus infects cattle, pigs, and sheep and many cloven-hoofed wildlife species. The infection... read more 
, malignant catarrhal fever Malignant Catarrhal Fever in Animals Malignant catarrhal fever is a severe, often fatal, lymphoproliferative disease of artiodactyls caused by ruminant gammaherpesviruses. Clinical signs include fever, oral and nasal erosions,... read more , and bovine viral diarrhea Bovine Viral Diarrhea and Mucosal Disease Complex Bovine viral diarrhea/mucosal disease is a pestivirus infection of cattle and other ruminants. Infection leads to immunosuppression and can cause signs in multiple body systems in addition to... read more . Epidemic diseases such as bluetongue Bluetongue in Ruminants Bluetongue is a viral disease of ruminants worldwide. Clinical signs in sheep result from vascular endothelial damage, including edema of the muzzle, tongue, and coronary bands. Diagnosis is... read more in ruminants, swine vesicular disease Swine Vesicular Disease Swine vesicular disease is a viral vesicular disease of pigs caused by an enterovirus closely related to human coxsackie virus B5. It is generally a mild disease that was endemic in Italy until... read more , and vesicular stomatitis Vesicular Stomatitis in Large Animals Vesicular stomatitis (VS) is a viral disease of livestock transmitted primarily by biting flies and midges. The disease results in characteristic vesicular lesions that can occur on the muzzle... read more in horses must be differentiated from other forms of acute noninfectious or infectious stomatitis.
