Association Between Exposure to Ehrlichia spp. and Risk of Developing Chronic Kidney Disease in Dogs

Abstract

ABSTRACT Ehrlichiosis is a common vector-borne disease caused by Ehrlichia spp. This retrospective matched cohort study was performed to determine if dogs with Ehrlichia spp. antibodies had an increased incidence of chronic kidney disease (CKD). Exposure to Ehrlichia spp. was defined as having an Ehrlichia spp. antibody–positive result recorded at any point in their available patient history. The outcome of CKD was defined as concurrent increased symmetric dimethylarginine (>14 µg/dL) and creatinine (>1.5 mg/dL) for a minimum of 25 days with inappropriate urine specific gravity (<1.030). Patients were matched using propensity score matching to control for age, geography, and breed. A total of 22,440 patients and controls in E canis–endemic regions of the United States were used in this analysis. Contingency tables were used to compare dogs with and without exposure to Ehrlichia spp.–infected ticks and CKD outcome. The relative risk of CKD for patients exposed to ticks carrying Ehrlichia spp. was found to be 2.12 (95% confidence interval [1.35–3.15], p < 0.0006). This study identified that testing positive for Ehrlichia spp. antibodies in E canis–endemic regions is associated with higher incidence of CKD in dogs.