Muscle disorders are referred to as myopathy. The term focal inflammatory myopathy refers to disorders of the chewing (masticatory) and eye (extraocular) muscles. This condition specifically affects group of muscles which are involved in chewing and the extraocular muscles which are adjacent to the eyeball and control eye movements.
When chewing or masticatory muscles are affected by this immune-mediated condition, it is known as Masticatory Muscle Myositis (MMM) and when eyeball muscles are affected, the condition is called Extraocular Myositis (EOM). Myositis is the medical term for muscle inflammation. A dog suffering from MMM will have inflammed jaws while a dog suffering from EOM will have inflammed muscles around the eyes.
Focal inflammatory myopathy is an immune-mediated disorder. In this condition, the dog's immune system attacks its body instead of attacking intruding organisms. This happens in response to antibodies (proteins used by immune system to identify and destroy foreign intruders). In this condition, the antibodies target the muscles of the affected dog.
Certain breeds are predisposed to masticatory muscle myositis (MMM) including cavalier King Charles spaniels, rottweilers, Dobermans, and samoyeds while golden retreivers are genetically more prone to extraocular myositis (EOM).
Dogs suffering from masticatory myositis will have pain when opening the jaw. They will show symptoms such as inability to pick up food or catch a ball, muscle swelling, muscle wasting (muscle atrophy) and problems with normal jaw movements.
Dogs that suffer from extraocular myositis typically show symptoms such as swelling around the eyes and protrusion of eyeball from socket.
