Masticatory muscle myositis is a painful autoimmune condition in dogs causing jaw swelling and lock-jaw, requiring prompt immunosuppressive treatment to prevent permanent scarring.
Dogs with acute MMM experience severe pain when attempting to eat, drink, or yawn, as inflamed jaw muscles create exquisite tenderness. Affected dogs may refuse food due to the pain of chewing and can become rapidly malnourished. Without prompt immunosuppressive treatment, the acute inflammatory phase resolves but leaves permanent fibrous scarring that mechanically prevents the jaw from opening - a state that permanently compromises eating ability and welfare. Early aggressive treatment prevents this irreversible outcome and restores normal quality of life.