Article Text

Download PDFPDF
Management and resolution of acquired myasthenia gravis in a carbimazole-treated hyperthyroid domestic shorthair cat
  1. Jenny Ellis and
  2. Simon Tappin
  1. Small Animal Internal Medicine, Dick White Referrals, Newmarket, UK
  1. Correspondence to Jenny Ellis; jenny.ellis{at}


An 11-year-old male neutered domestic shorthair cat presented with acute onset signs of generalised weakness and neck ventroflexion. He had been diagnosed with hyperthyroidism two months previously and been treated with daily carbimazole. No haematological, biochemical or electrolyte abnormalities were evident to explain his signs; thoracic and abdominal imaging was unremarkable. A positive response to a neostigmine response test and high acetylcholine receptor antibody titre were consistent with a diagnosis of myasthenia gravis. The temporal association with treatment of hyperthyroidism suggested acquired myasthenia gravis secondary to carbimazole, and the cat underwent successful surgery for thyroidectomy to avoid the need for ongoing medical therapy. Acetylcholine receptor antibody levels remained high four months later before returning to normal after a further two months. Clinical signs were completely controlled with pyridostigmine, which was tapered and eventually withdrawn, and the cat returned to a normal quality of life.

  • carbimazole
  • myasthenia gravis
  • pyridostigmine
View Full Text

Statistics from


  • Contributors Both JE and ST contributed significantly to the planning, conduct and reporting of the work described in the article.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data are available.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.