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Atenolol for Hyperthyroid Cats

Henik, R. A., R. L. Stepien, et al. (2008). “Efficacy of atenolol as a single antihypertensive agent in hyperthyroid cats.” Journal of Feline Medicine & Surgery 10(6): 577-582.

Hypertension is a common complication of hyperthyroidism and chronic renal disease in cats. Various drugs may be used to treat feline hypertension, but the drug of choice appears to be amlodipine due to its efficacy and low incidence of adverse effects. However, in cats with hypertension caused by hyperthyroidism, beta-blocking drugs such as atenolol have been suggested to slow the heart rate and block effects of thyroid hormone on the cardiovascular system. While atenolol has been shown to be ineffective in treating hypertension associated with chronic renal disease, it has not been previously investigated for treatment of cats with hyperthyroidism. In this retrospective study, 20 hyperthyroid cats with systolic blood pressure over 160 mmHg were treated with atenolol (1-2 mg/kg, PO, BID). All cats were treated for a minimum of 5 days before reassessment and treatment with radioactive iodine. While both heart rate and systolic blood pressure decreased in the cats, successful clinical control of blood pressure was not achieved in 70% of the cases. The investigators concluded that while atenolol successfully controls heart rate in hyperthyroid cats, the addition of another drug is needed to treat hypertension.
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Related articles:
Trepanier LA. Pharmacologic management of feline hyperthyroidism. Vet Clin North Am Small Anim Pract. 2007 Jul;37(4):775-88
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