Peer-reviewed veterinary case report
Cat treated with methimazole for hyperthyroidism developed muscle
By Bell, E T et al.·Published in The Journal of small animal practice·2012·Faculty of Veterinary Science, Australia·View original on PubMed →
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Original publication title: Immune-mediated myasthenia gravis in a methimazole-treated cat.
- Species:
- cat
Plain-English summary
A 12-year-old female neutered Ragdoll cat was brought in because she was weak and regurgitating. She had been treated with a medication called methimazole for hyperthyroidism for about 10 weeks. Tests showed she had a condition called myasthenia gravis, which affects muscle strength. After stopping the methimazole and starting a different medication, pyridostigmine, her symptoms improved and her test results returned to normal. The vet later managed her hyperthyroidism with another medication, carbimazole, without any further issues.
People also search for: cat weakness and regurgitation · myasthenia gravis in cats · methimazole side effects in cats
Abstract
A 12-year-old female neutered ragdoll crossbred cat was presented for investigation of generalised weakness and regurgitation. The cat was being treated with transdermal methimazole for hyper-thyroidism, which had been diagnosed 10 weeks previously. An acetylcholine receptor antibody titre was consistent with acquired myasthenia gravis. Withdrawal of methimazole and treatment with pyridostigmine was followed by resolution of clinical signs and reduction of the acetylcholine -receptor antibody titre. Medical control of hyperthyroidism was subsequently achieved with carbimazole, administered in conjunction with pyridostigmine, and no recurrence of clinical signs was observed. Myasthenia gravis is an uncommon but clinically significant adverse effect of methimazole therapy in cats, and may be caused by immunomodulatory properties of this drug. An adverse drug reaction should be considered in cats receiving methimazole that develop myasthenia gravis, and potentially also other immune-mediated disorders.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/22957965/