Background: Hypochloremia is a strong negative prognostic factor in humans with congestive heart failure (CHF), but the implications of electrolyte abnormalities in small animals with acute CHF are unclear.Objectives: To document electrolyte abnormalities present upon admission of small animals with acute CHF, and to assess the relationship between electrolyte concentrations and diuretic dose, duration of hospitalization and survival time.Animals: Forty-six dogs and 34 cats with first onset of acute CHF.Methods: Retrospective study. The associations between electrolyte concentrations and diuretic doses were evaluated with Spearman rank correlation coefficients. Relationship with duration of hospitalization and survival were assessed by simple linear regression and Cox proportional hazard regression, respectively. Results:The most commonly encountered electrolyte anomaly was hypochloremia observed in 24% (9/46 dogs and 10/34 cats) of cases. In dogs only, a significant negative correlation was identified between serum chloride concentrations at admission (median 113 mmol/L [97-125]) and furosemide doses both at discharge (median 5.2 mg/kg/day [1.72-9.57]; r = À0.59; P < .001) and at end-stage heart failure (median 4.7 mg/kg/day [2.02-7.28]; r = À0.62; P = .005). No significant hazard ratios were found for duration of hospitalization nor survival time for any of the electrolyte concentrations.Conclusions and Clinical Importance: The observed association between serum chloride concentrations and diuretic doses suggests that hypochloremia could serve as a marker of disease severity and therapeutic response in dogs with acute CHF.

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Background: In people and dogs, torasemide has higher bioavailability, longer half-life, and longer duration of action than equivalent doses of furosemide but data regarding pharmacological properties of torasemide in cats are limited.Objective: To assess pharmacokinetic and pharmacodynamic parameters of torasemide in healthy cats, and to investigate the effects of a single administration of torasemide on indicators of diuresis, plasma creatinine concentration, blood pressure, electrolyte concentrations and markers of the renin-angiotensin-aldosterone system (RAAS).Animals: Six clinically healthy adult European shorthair cats.Methods: Randomized 4-period crossover design with 3 groups and 4 treatments. Pharmacokinetic parameters were obtained using a noncompartmental analysis, and the clinically effective dose was assessed using a Hill model.Results: Mean absolute bioavailability was estimated at 88.1%. Mean total body clearance was 3.64 mL/h/kg and mean terminal half-life was 12.9 hours. Urine output significantly increased after torasemide administration (P < .001). The urine sodium : potassium ratio (uNa : uK) paralleled and was statistically correlated to urine output (P < .001). Administration of a single torasemide dose led to a significant dose-dependent increase in urine aldosterone : creatinine ratio (uAldo : C; P < .001) and a transient decrease in plasma potassium concentration (P < .001) but did not affect blood pressure or plasma creatinine concentration. Conclusions and Clinical Importance:A single torasemide dose leads to a significant increase in diuresis and renin-angiotensin-aldosterone system (RAAS) activation in healthy cats, with high absolute bioavailability, and without clinically relevant adverse Abbreviations: %D, fraction of the dose eliminated in urine; AUC INF , area under the concentration-time curve extrapolated to infinity; CHF, congestive heart failure; Cl, chloride; Cl R , renal clearance; Cmax, maximal plasma concentration; D, actual administered dose; E, excreted urine volume in 24 hours; Emax, maximum urine volume excreted in 24 hours; EX50, eliminated urinary amount of torasemide which induces an excreted urine volume of half of the Emax; F, absolute bioavailability; Fu, absolute bioavailability with urine data; HDO, high definition oscillometry; HF, heart failure; K, potassium; MRT INF , mean residence time extrapolated to infinity; Na, sodium; pCr, plasma creatinine; RAAS, renin-angiotensin-aldosterone system; T ½λz , mean terminal half-life;T max , Time to reach maximum plasma concentration; uAldo : C, urine aldosterone : creatinine ratio; uCr urinary, creatinin; USG, urine specific gravity; V ss mean, volume of distribution; X u total, eliminated urinary amount of torasemide in 24 hours; X ∞ u , total eliminated urinary amount of torasemide in 24 hours extrapolated to infinity.