Hypochloremia is negatively associated with outcomes in cats with stable congestive heart failure.

Hypochloremia independently predicts shorter survival in stable feline CHF; monitoring and correcting serum chloride is recommended.

This retrospective cohort study evaluated the prognostic significance of serum chloride concentration (s[Cl-]) in 84 cats with stable congestive heart failure (CHF), assessed at least one week post-hospitalization. Hypochloremia, defined as s[Cl-] < 112 mEq/L, was identified in 15 cats (approximately 18%). Using Kaplan-Meier survival analysis and Cox proportional hazards regression, hypochloremia was independently associated with a 2.82-fold increased risk of death and significantly shorter median survival (159 days vs. 392 days for normochloremic cats). Hypochloremic cats received significantly higher diuretic doses, though diuretic dose itself was not an independent predictor of outcome in multivariable modeling, suggesting chloride depletion may represent a distinct pathophysiologic mechanism beyond simple diuretic excess. Two additional independent predictors were identified: pimobendan use was associated with higher death risk (HR 1.96), likely reflecting its use in more advanced disease, while normal BUN (< 28 mg/dL) was protective (HR 0.45), consistent with renal function as a known prognostic marker. The findings parallel established data in human cardiology, where hypochloremia independently predicts worse outcomes in heart failure patients. Limitations include the retrospective, single-institution design and relatively small hypochloremic group. The authors advocate for prospective studies and suggest that clinical efforts to normalize serum chloride—through dietary sodium chloride supplementation or diuretic dose adjustment—warrant consideration in feline CHF management.

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