Generalised lymphadenomegaly associated with methimazole treatment in a hyperthyroid cat

Authors

  • S. J. M. Niessen,

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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  • M. J. Voyce,

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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  • L. De Villiers,

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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  • J. Hargreaves,

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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  • A. S. Blunden,

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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  • H. M. Syme

    1. Queen Mother Hospital, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA
      *Oakwood Veterinary Surgery, Harper Lane, Radlett, Herts WD7 7HY
      †Abbey Veterinary Services, 89 Queen Street, Newton Abbot, Devon TQ12 2BG
      ‡Animal Health Trust, Diagnostic Laboratory Services, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
    Search for more papers by this author

Abstract

A nine-year-old, domestic shorthair cat was diagnosed with hyperthyroidism and treated with methimazole, which resulted in lethargy, inappetence and marked generalised lymphadenomegaly within two weeks of initiation of therapy. Cytology, histopathology and immunohistochemistry were suggestive of atypical lymphoid hyperplasia. Cessation of treatment resulted in resolution of all clinical signs and physical abnormalities within two days. Subsequent treatment with radioactive iodine cured this cat of its hyperthyroidism. The lymphadenomegaly did not return at any stage and the cat is currently asymptomatic. Although methimazole administration for feline hyperthyroidism has been associated with many side effects, lymphadenomegaly has, to the authors’ knowledge, not been previously reported.

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