The magnitude of hyperchloremia in horses is associated with diarrhea and renal function.

Objective: To describe the signalment, diagnosis, treatment, and laboratory characteristics of horses with hyperchloremia and identify factors associated with the magnitude of the increased chloride concentration.

Methods: Horses with a chloride concentration greater than 108 mEq/L were included in this retrospective study. Descriptive statistics and multiple linear regression analysis were used to identify associations between diagnosis, treatment, and laboratory variables and the magnitude of hyperchloremia.

Results: 134 horses met the inclusion criteria for this study. Creatinine was a significant predictor (unstandardized regression coefficient [B] = 1.36; 95% CI, 0.51 to 2.21; P = .003) of an increased chloride concentration as was the presence of diarrhea (B = 1.43; 95% CI, 0.08 to 2.79; P = .039). Sodium concentration also showed a strong association with chloride in all models (B = 0.42; 95% CI, 0.32 to 0.53; P < .001). The mortality rate for the horses in this study was 24%.

Conclusions: Horses with diarrhea are likely to be at risk for more profound hyperchloremia. There was also a positive association between increased creatinine and increased chloride.

Clinical relevance: Equine practitioners who diagnose and treat horses with diarrhea should be aware that significant hyperchloremia could develop. The changes in chloride concentration associated with increasing creatinine values require further research, but the finding supports the association between hyperchloremia and acute kidney injury observed in other species.