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Article
Goitrous hypothyroidism associated with treatment with trimethoprim-sulfamethoxazole in a young dog
Journal of the American Veterinary Medical Association (2008)
  • D M Seelig
  • Jacqueline C. Whittemore, University of Tennessee, Knoxville
  • M R Lappin
  • A M Myers
  • P R Avery
Abstract

CASE DESCRIPTION: A 16-week-old female Boxer that had been treated for 5 weeks with trimethoprim-sulfamethoxazole and chloramphenicol because of aspiration pneumonia was evaluated for bilaterally symmetric masses in the subcutaneous tissues of the ventral neck, in the region of the larynx. CLINICAL FINDINGS: Fine-needle aspirates were obtained from the neck masses; cytologic examination revealed well-differentiated thyroid epithelial tissue. A blood sample was collected for serum biochemical and thyroid function analyses. Mild hyperphosphatemia, severe hypercholesterolemia, mild hyperkalemia, and a mild increase in creatine kinase activity were identified. Serum concentration of total thyroxine was less than the lower reference limit, and that of thyroid-stimulating hormone was greater than the upper reference limit. Findings were consistent with a diagnosis of clinical hypothyroidism in a skeletally immature dog. TREATMENT AND OUTCOME: Treatment with trimethoprim-sulfamethoxazole was discontinued. The dog was reevaluated 3 weeks later, at which time the neck masses were markedly decreased in size. Serum concentrations of cholesterol and potassium were lower; serum concentrations of total thyroxine and thyroid-stimulating hormone were near or within respective reference ranges. Age-appropriate increases in serum phosphorus concentration and serum alkaline phosphatase activity were also detected. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of antimicrobial-induced goiter in a dog. Cytologic examination of fine-needle aspirates and interpretation of data from serum biochemical and thyroid function analyses were needed to obtain a definitive diagnosis. Practitioners should include goiter among the differential diagnoses for ventral neck swellings in young dogs receiving potentiated sulfonamide antimicrobials.

Publication Date
April 15, 2008
Citation Information
D M Seelig, Jacqueline C. Whittemore, M R Lappin, A M Myers, et al.. "Goitrous hypothyroidism associated with treatment with trimethoprim-sulfamethoxazole in a young dog" Journal of the American Veterinary Medical Association Vol. 232 Iss. 8 (2008)
Available at: http://works.bepress.com/jacqueline_c_whittemore/6/