Correction of serum chloride concentration in dogs with congestive heart failure
Darcy B. Adin, Clarke E. Atkins, Leonel Londoño, Bruna Del Nero
Abstract
Abstract Background Hypochloremia associated with congestive heart failure (CHF) in dogs is likely multifactorial. Loop diuretics cause 1:2 sodium [Na+]:chloride [Cl−] loss, whereas water retention causes a 1:1 [Na+]:[Cl−] dilution. Mathematical [Cl−] correction separates these effects on [Cl−]. Hypothesis We hypothesized that corrected [Cl−] (c[Cl−]) would not differ from measured [Cl−] (m[Cl−]) in dogs with controlled CHF because of loop diuretics, and dogs with refractory CHF would have higher c[Cl−] than m[Cl−], indicating relative water excess. Animals Seventy-one client-owned dogs with acquired heart disease, without CHF (NO-CHF), 76 with Stage C CHF and 24 with Stage D CHF. Methods Clinicopathological data from a previous study were retrospectively analyzed. Corrected [Cl−], m[Cl−], and differences were compared among NO-CHF, Stage C CHF, and Stage D CHF, using the formula: c[Cl−] = (mid-reference range [Na+]/measured [Na+]) × m[Cl−]. Results Corrected [Cl−] and m[Cl−] were lower in Stage D vs Stage C and NO-CHF (all P < .0001). The c[Cl−] was higher than m[Cl−] in Stage D (P < .0001) but not Stage C or NO-CHF. Median difference between c[Cl−] and m[Cl−] was higher for Stage D vs Stage C (P = .0003). No hypochloremic Stage D dogs had normal c[Cl−], but 11/24 had [Cl−] that was increased by >2 mmol/L. Conclusions and Clinical Importance Serum [Cl−] increased after mathematical correction in Stage D CHF dogs but not in Stage C and NO-CHF dogs. Although c[Cl−] was higher than m[Cl−] in Stage D dogs supportive of relative water excess, hypochloremia persisted, consistent with concurrent loop diuretic effects on electrolytes. Future study correlating c[Cl−] to antidiuretic hormone concentrations is warranted.