Original Scientific Article
Hyperthyroidism in the domestic cat (Felis catus): informed treatment choice based on survival analysis
Fernando Mata*,
Ravneet Bhuller

Mac Vet Rev 2022; 45 (1): 71 - 78


Received: 15 September 2021

Received in revised form: 06 February 2022

Accepted: 11 February 2022

Available Online First: 28 February 2022

Published on: 15 March 2022

Correspondence: Fernando Mata, fernandomata@ipvc.pt


Hyperthyroidism is the most frequently diagnosed endocrine disorder in cats. Therapy may include pharmacological, surgical (thyroidectomy), radioactive (iodine), and dietary treatment. The choice of treatment is believed to be strongly influenced by the veterinarian’s experience, level of education, and knowledge of the current scientific literature. The history of survival rates can affect the decision for treatment by both the veterinarian and the owner. This study aimed to explore the longevity in cats diagnosed with hyperthyroidism and to identify significant variables which affect survival rates by using retrospective data from the practice. A multivariate Cox regression was applied with the following results: surgical thyroidectomy and methimazole medication produced similar longevity (median 23.5 months, P>0.05); Domestic Short Hair cats survived longer than pure breeds (median 27.2 vs 9.4 months, P<0.05); as do cats without chronic renal disease (median 28.1 vs 6.2 months, P<0.001); and those with low activities of alanine aminotransferase (median 27.1 vs 17.0 months, P<0.01). Hyperthyroidism is comorbid with renal diseases, but no cumulative effect was found on survivability. There was no difference in survival rates between surgical and pharmaceutical treatment, therefore the discussion of treatment options with owners can focus on other factors (e.g., cost, owners’ compliance, cats’ tolerance to medication, presence of comorbidities). We propose that surgery may be the preferred treatment when the survival rates are expected to be higher than one year. This would avoid high costs and potential side effects of medication.

Keywords: cats, hyperthyroidism, methimazole treatment, survivability, thyroidectomy


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© 2022 Mata F. This is an open-access article published under the terms of the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Conflict of Interest Statement

The authors have declared that no competing interests exist.

Citation Information

Macedonian Veterinary Review. Volume 45, Issue 1, Pages 71-78, e-ISSN 1857-7415, p-ISSN 1409-7621, DOI: 10.2478/macvetrev-2022-0015, 2022