## Overview Masseter myositis is inflammation of the cheek muscles causing painful swelling and difficulty opening the mouth (trismus). Horses drop feed and may lose weight. Causes include dental infection, temporomandibular joint inflammation, trauma, or rarely immune-mediated disease. ## Causes Extension of dental or joint infection, trauma, or primary muscle inflammation. ## Diagnosis Palpation of firm, painful masseters, observation of restricted jaw opening, and investigation of the teeth and temporomandibular joints. ## Treatment Anti-inflammatories, treatment of any dental or joint infection, and soft feed. Immune-mediated cases may need corticosteroids. ## Recovery and Prognosis Good when the underlying cause is identified and treated. ## Prevention Regular dental care and prompt treatment of oral infections.
swollen firm jaw muscles; reluctance to open the mouth; dropping feed; weight loss; pain on palpation of the cheeks
## Overview Masseter myositis is inflammation of the cheek muscles causing painful swelling and difficulty opening the mouth (trismus). Horses drop feed and may lose weight. Causes include dental infection, temporomandibular joint inflammation, trauma, or rarely immune-mediated disease. ## Causes Extension of dental or joint infection, trauma, or primary muscle inflammation. ## Diagnosis Palpation of firm, painful masseters, observation of restricted jaw opening, and investigation of the teeth and temporomandibular joints. ## Treatment Anti-inflammatories, treatment of any dental or joint infection, and soft feed. Immune-mediated cases may need corticosteroids. ## Recovery and Prognosis Good when the underlying cause is identified and treated. ## Prevention Regular dental care and prompt treatment of oral infections.
swollen firm jaw muscles; reluctance to open the mouth; dropping feed; weight loss; pain on palpation of the cheeks