Myasthenia gravis (MG) is an acquired neurological disease characterised by muscle weakness and exercise intolerance in dogs.
Myasthenia gravis may also develop as a paraneoplastic syndrome associated with thymoma.
These dogs present with exercise-induced stiffness, regurgitation and respiratory difficulty. Facial, pharyngeal, or esophageal weakness is common, and in many cases there is megaesophagus without generalized weakness (focal myasthenia). Aspiration pneumonia is a frequent complications.
Diagnosis is based on response to intravenous edrophonium (0.1-0.2 mg/kg) and detection of antibodies in serum.
Artificial ventilation may be required in critical cases.
Immunosuppressive dosages of prednisolone are recommended in animals that do not respond to anticholinesterase therapy.
Prognosis is generally good, and many dogs will undergo spontaneous remission, evident by a decrease in antibody titer. The prognosis is guarded for animals with aspiration pneumonia or persistent weakness.
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