Feline
Update (June 10, 2026): No Evidence of Circulating RAAS Activation in Cats with Non-Hypertensive CKD or Untreated Hypertension
TL;DR
A May 2026 prospective study measuring circulating renin-angiotensin-aldosterone system (RAAS) peptides in cats found no evidence of classical RAAS activation in non-hypertensive chronic kidney disease or untreated systemic hypertension - a finding that refines how clinicians think about RAAS-targeted therapy such as telmisartan.
What just dropped
Lourenco and colleagues published "Circulating renin-angiotensin-aldosterone system markers in cats with non-hypertensive chronic kidney disease or systemic arterial hypertension" in the Journal of Veterinary Internal Medicine (May 2026; PMID 42117720; DOI 10.1093/jvimsj/aalag079), from the University of Georgia College of Veterinary Medicine.
- This prospective, single-center, observational study compared serum equilibrium concentrations of angiotensin peptides and aldosterone among healthy cats (n=17), cats with non-hypertensive CKD (NHT-CKD; serum creatinine at least 1.6 mg/dL, systolic BP under 160 mmHg; n=17), and cats with untreated systemic arterial hypertension (SAH; n=6).
- Mean serum angiotensin I, II, and III concentrations were lower in cats with untreated SAH versus healthy controls across unadjusted and adjusted models (for example, angiotensin II geometric mean 33.63 versus 124.24 pmol/L; all P at or below 0.038).
- Controlling for diet but not age, angiotensin II (P=0.043) and III (P=0.019) were also lower in NHT-CKD cats versus controls.
- Serum aldosterone did not differ between groups, and the authors concluded that evidence of circulating RAAS activation in cats with NHT-CKD or untreated SAH was not found.
Context
Telmisartan (Semintra) is an angiotensin-receptor blocker (ARB) that acts on the RAAS, and it is used in cats for proteinuria associated with CKD and for systemic hypertension. The rationale for RAAS-targeted therapy rests partly on the assumption of RAAS involvement in disease progression. This study measured both the classical and alternative circulating RAAS pathways and, notably, did not find evidence of circulating classical RAAS activation in these two common feline populations - although it did detect that all angiotensin peptides except angiotensin IV increased during amlodipine therapy in hypertensive cats. A companion 2026 review of feline cardiovascular-kidney comorbidities (Coleman and Lourenco; PMID 41863293) underscores how interconnected heart and kidney disease are in cats and how therapy directed at one system can affect the other.
The finding does not negate the established clinical benefit of ARBs on proteinuria and blood pressure; rather, it highlights that the circulating RAAS picture in cats is more nuanced than a simple "activated system" model and that diet and age meaningfully modify these measurements.
What this changes in the Telmisartan (Semintra) evergreen
The telmisartan page (https://www.thevoyage.ai/forvets/knowledge/telmisartan-feline-ckd-proteinuria) summarises the ARB mechanism and the proteinuria/hypertension evidence base. This study adds physiological nuance to the mechanistic rationale: in cats with non-hypertensive CKD or untreated hypertension, the authors did not find evidence of circulating classical RAAS activation, and serum aldosterone did not differ between groups. Clinically, telmisartan's documented effects on proteinuria and blood pressure remain the basis for its use; this work simply cautions against assuming a uniformly upregulated circulating RAAS as the explanation, and it flags that diet and age must be accounted for when interpreting RAAS biomarkers. It is a single-center observational study with a small hypertensive group (n=6), so conclusions about the SAH population in particular are preliminary.
References
- Lourenco BN, Huang JHC, Reno L, Toborowsky C, Coleman AE. Circulating renin-angiotensin-aldosterone system markers in cats with non-hypertensive chronic kidney disease or systemic arterial hypertension. J Vet Intern Med. 2026;40(3):aalag079. https://pubmed.ncbi.nlm.nih.gov/42117720/
- Coleman AE, Lourenco BN. Feline comorbidities: cardiovascular and kidney diseases. J Feline Med Surg. 2026;28(3):1098612X251407521. https://pubmed.ncbi.nlm.nih.gov/41863293/
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Changelog
- 2026-06-10: First published.
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