Cardiology Resident University of Florida College of Veterinary Medicine
Background: Serum chloride concentrations (s[Cl]) can be low in congestive heart failure (CHF). Although likely multifactorial, hypochloremia < 100 mEq/L is associated with poor outcomes in people.
Hypothesis/
Objectives: We hypothesized that hypochloremia would be associated with poor survival in dogs with CHF. Animals: A total of 292 stable CHF dogs were included (229 degenerative valve disease, 31 dilated cardiomyopathy, 21 congenital heart disease, 6 pulmonary hypertension, and 5 arrhythmogenic cardiomyopathy).
Methods: Single institutional retrospective study from 2014-2024. Biochemical variables, medications, and outcome data were extracted from medical records at the first recheck after initial CHF episode. Exclusion criteria were active CHF, absence of s[Cl] on bloodwork, point-of-care bloodwork, and clinically important vomiting or diarrhea. Dogs were grouped by s[Cl] < 100 mEq/L. Risk of death associated with s[Cl] < 100 mEq/L, biochemical variables, and medications was evaluated with Cox regression analysis and survival was assessed using test Kaplan-Meier analysis using log-rank sum.
Results: Median s[Cl] was 106.5 mEq/L (range 85.0–119.0). Serum [Cl] < 100 mEq/L was associated with risk of death (hazard ratio 2.649; CI 1.265-5.311), with significant survival difference between dogs with s[Cl] < 100 mEq/L (115 days) and dogs with s[Cl] ≥ 100 mEq/L (196 days) (P=0.0116). Medications and other biochemical variables were not associated with risk of death or outcome.
Conclusions and Clinical Importance: Moderate to severe hypochloremia (s[Cl] < 100 mEq/L) in dogs with stable CHF is associated with shorter survival times compared to s[Cl] ≥ 100 mEq/L. These findings support efforts to increase s[Cl] levels above 100 mEq/L in dogs with CHF.
