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Urine sodium concentration and diuretic responsiveness in dogs receiving orally administered loop diuretics for

Audrey Rollins1, Darcy B Adin2, Alexandra V Crooks1

  • 1Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.

Journal of Veterinary Internal Medicine
|June 16, 2026
PubMed

Insights

Urine sodium concentration (uNa) in dogs with heart failure indicates diuretic responsiveness, even when diuretic dose doesn't predict it. Low uNa suggests poor response, prompting further investigation into causes of diuretic resistance.

Area of Science:

  • Veterinary Cardiology
  • Pharmacology
  • Clinical Pathology

Background:

  • Urine sodium concentration (uNa) is a key indicator of diuretic responsiveness (DR) in congestive heart failure (CHF).
  • In humans with chronic CHF on loop diuretics, low uNa correlates with adverse outcomes.
  • Diuretic responsiveness in dogs with chronic CHF is not well understood.

Purpose of the Study:

  • To measure urine sodium concentration (uNa) and related variables in dogs with chronic congestive heart failure receiving oral loop diuretics.
  • To explore associations between uNa, diuretic treatment parameters, and feeding times.

Main Methods:

  • Prospective longitudinal observational study involving 11 client-owned dogs.
  • Owners collected convenience urine samples over 5 days.
  • Mixed effects linear regression analyzed associations between urine electrolytes, diuretic concentrations, dose, duration, and timing of administration.

Main Results:

  • A total of 189 urine samples were analyzed; median uNa was 27 mmol/L.
  • 45% of dogs consistently showed low uNa (<70 mmol/L), indicating poor diuretic responsiveness.
  • Neither diuretic dose nor duration significantly predicted uNa; urine diuretic concentration also showed no significant association with uNa.

Conclusions:

  • Urine sodium concentration and diuretic concentration measurements can identify dogs with low natriuresis.
  • Diuretic dose or duration does not reliably predict natriuretic response in dogs.
  • Observed uNa patterns suggest potential causes for low diuretic responsiveness that require further research.
Abstract

Keywords:
diuretic resistancefurosemidenatriuresistorsemide

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