Masticatory muscle myositis (MMM) is an immune-mediated inflammation of the muscles of mastication, caused by antibodies against a special myosin (type 2M) found in those muscles. It is a well-known disease of dogs. In cats it is so rarely reported that this guide is built on two single-cat case reports, and the NAVLE point is to know it can occur, not to memorize canine numbers.
Key facts
Masticatory muscle myositis at a glance- Species and system: mainly dogs; reported in two cats. Musculoskeletal (masticatory muscles).
- Cause: autoantibodies against type 2M fibers in the temporalis, masseter and pterygoid muscles (MSD).
- Cat reports: a 1-year-old cat with trismus and end-stage disease (Blazejewski 2018) and a 4-year-old cat with facial swelling and exophthalmos (Armellini 2021).
- Key test: serum 2M antibody ELISA, run with a canine assay because no feline assay exists; muscle biopsy gives prognosis.
- Treatment: immunosuppressive corticosteroids, tapered slowly; ciclosporin can be added.
- Zoonotic or reportable: no.
What's inside
12 sections in the full guide- Key facts
- How the NAVLE tests this
- What is known in cats, and what is not
- Cause and pathophysiology
- Clinical signs
- Diagnosis
- Differential diagnoses
- Treatment and management
- Prognosis
- Quick review
- Test yourself
- References
The full guide also has 5 tables, 1 figure, 3 self-test questions and 5 references, available to NAVLE members.
Read the full study guide
The full guide is part of every NAVLE plan, with diagnosis and treatment tables, figures, a quick review and self-test questions. Start a free trial to try the question bank, or log in if you are already a member.