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Update (June 16, 2026): An Oral Telmisartan Suppression Test Shows Promise for Diagnosing Primary Hyperaldosteronism in Cats

Jun 16, 2026 2 min read

TL;DR. A proof-of-concept feline study suggests an oral telmisartan suppression test could help diagnose primary hyperaldosteronism, while a separate glaucoma study reaffirms telmisartan's blood-pressure tolerability in cats.

What just dropped

  • Prospective placebo-controlled crossover study (https://europepmc.org/articles/PMC10365039): in healthy cats, an oral telmisartan dose significantly lowered plasma aldosterone, whereas in cats with primary hyperaldosteronism it produced no significant change, supporting a telmisartan suppression test for diagnosis.
  • No adverse effects such as hyperkalemia or systemic hypotension were observed in any cat in that study.
  • A six-month feline glaucoma study (https://europepmc.org/articles/PMC11407481) found daily oral telmisartan was well tolerated and did not have a detrimental effect on blood pressure or ocular perfusion pressure, though it did not lower intraocular pressure.

Context

Telmisartan (Semintra) is an angiotensin II type 1 receptor blocker licensed in cats for systemic hypertension and for proteinuria associated with chronic kidney disease. Two recent studies probe its angiotensin-axis pharmacology in cats from new angles.

In the Fabres 2023 study, 10 healthy cats and 6 cats with primary hyperaldosteronism (PHA) underwent a telmisartan suppression test. A telmisartan dose suppressed aldosterone in healthy cats but not in PHA cats, mirroring how human aldosterone-suppression testing works and offering a possible tool for a condition that remains difficult to diagnose. The Oikawa 2024 study, while focused on glaucoma rather than diagnosis, independently confirms that telmisartan was well tolerated and did not adversely affect blood pressure or ocular perfusion pressure over six months in cats, including a cohort with spontaneous glaucoma.

What this changes in telmisartan (Semintra) for proteinuria and hypertension in cats with CKD (https://www.thevoyage.ai/forvets/knowledge/telmisartan-feline-ckd-proteinuria)

These data extend the picture of telmisartan in cats beyond its labeled blood-pressure and proteinuria roles: a potential diagnostic application in suspected hyperaldosteronism, plus reassurance on blood-pressure tolerability from an independent six-month cohort. The suppression test is proof-of-concept and not a validated clinical protocol, and none of this changes approved dosing, which remains a label and formulary decision.

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References

  1. Fabres V, Dumont R, Garcia M, et al. Evaluation of oral telmisartan administration as a suppression test for diagnosis of primary hyperaldosteronism in cats. J Vet Intern Med. 2023;37(4):1341-1347. https://europepmc.org/articles/PMC10365039
  2. Oikawa K, Kiland JA, Mathu V, et al. Effects of Telmisartan on Intraocular Pressure, Blood Pressure, and Ocular Perfusion Pressure in Normal and Glaucomatous Cats. Transl Vis Sci Technol. 2024;13(9):15. https://europepmc.org/articles/PMC11407481

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References

  1. Fabres V, Dumont R, Garcia M, et al. Evaluation of oral telmisartan administration as a suppression test for diagnosis of primary hyperaldosteronism in cats. J Vet Intern Med. 2023. (2023)
  2. Oikawa K, Kiland JA, Mathu V, et al. Effects of Telmisartan on Intraocular Pressure, Blood Pressure, and Ocular Perfusion Pressure in Normal and Glaucomatous Cats. Transl Vis Sci Technol. 2024. (2024)

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