Retrospective Evaluation of the Prevalence and Prognosis of Hypochloremia in Dogs and Cats.

OBJECTIVE: To determine the prevalence, case-fatality rate, and primary disease processes associated with corrected hypochloremia (hypo[Cl-]) in dogs and cats. DESIGN: Single-center retrospective study. SETTING: Electronic medical records were reviewed to identify dogs and cats with at least one chloride and sodium concentration measured simultaneously during a 60-month period. ANIMALS: A total of 17,120 dogs and 4197 cats presented to a veterinary teaching hospital. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Measured hypo[Cl-] was diagnosed in 23.3% (3981/17,120) dogs and 59.0% (2475/4197) cats. Corrected hypo[Cl-] was diagnosed in 13.9% (2388/17,120) dogs and 34.9% (1463/4197) cats. The case-fatality rates were higher in animals with measured and corrected hypo[Cl-] than those with normal corrected [Cl-] (p < 0.0001). The case-fatality rate was also higher in cats with corrected hypo[Cl-] than those with measured hypo[Cl-] (p = 0.0002), but they were not different in dogs (p = 0.74). Of the dogs and cats with corrected hypo[Cl-], a total of 74.5% (1779/2388) dogs and 74.6% (1091/1463) cats were categorized as prehospital corrected hypo[Cl-], and a total of 20.9% (498/2388) dogs and 17.3% (253/1463) cats were categorized as hospital-acquired corrected hypo[Cl-]. The case-fatality rates of dogs and cats with hospital-acquired corrected hypo[Cl-] were higher than those with prehospital corrected hypo[Cl-] (p < 0.0001). Various primary disease processes were identified in animals with corrected hypo[Cl-]. Of these, urologic, cardiovascular, and gastrointestinal diseases were the three most common disease processes identified in dogs and cats with corrected hypo[Cl-]. CONCLUSIONS: Corrected hypo[Cl-] was a common electrolyte abnormality and was associated with higher case-fatality rates than normal corrected [Cl-]. Various disease processes were associated with corrected hypo[Cl-], and closer attention to corrected hypo[Cl-] is warranted.