Myasthenia gravis in dogs: treatment with pyridostigmine
7-year-old Golden Retriever with generalised myasthenia gravis confirmed by acetylcholine receptor antibodies. It has megaoesophagus and mild aspiration pneumonia in the right middle lung lobe. Radiographs show no mediastinal mass.
What is the most appropriate initial treatment plan?
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A. Oral pyridostigmine (parenteral neostigmine if oral intake is not tolerated), feeding in an upright position and an antibiotic for the pneumonia
Correct. The anticholinesterase is the mainstay of treatment. While aspiration pneumonia is present, immunosuppression is avoided; corticosteroids are reserved for cases with an inadequate response and started at low doses.
B. Prednisolone at immunosuppressive doses from day one
High-dose corticosteroids can worsen weakness early in treatment and increase the risk of the aspiration pneumonia progressing.
C. Urgent thymectomy even though no mediastinal mass is seen
Thymectomy is only indicated if there is a thymoma. In dogs, most cases of acquired myasthenia are not associated with thymoma.
D. No specific treatment: wait for spontaneous remission
Spontaneous remission is common, but it takes months. Without treatment the weakness and regurgitation persist, and so does the risk of aspiration, the main cause of death.
lightbulb Key takeaway
Many dogs without thymoma go into spontaneous remission within a few months: repeat antibody titres every 6–8 weeks and withdraw pyridostigmine once they normalise. Overdose causes a cholinergic crisis (hypersalivation, diarrhoea, fasciculations and more weakness). Avoid drugs that impair neuromuscular transmission, such as aminoglycosides.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.