Retrospective evaluation of acute kidney injury in horses treated with nonnitrogenous bisphosphonates (2013–2020): 8 cases

Abstract Objective To describe a population of horses with acute kidney injury (AKI) following administration of bisphosphonates including clinical signs, clinicopathologic data, treatment, and outcome. Design Retrospective study from August 2013 to July 2020. Setting Veterinary university teaching hospital. Animals Eight adult horses with AKI following administration of nonnitrogenous bisphosphonates. Interventions None. Measurements and Main Results Five horses received intramuscular clodronate (5/8; 62.5%) and 3 horses received intravenous tiludronate (3/8; 37.5%). Six horses (6/8; 75%) received concurrent nonsteroidal anti‐inflammatory drugs. The most common initial presenting complaint was poor appetite (6/8; 75%), followed by abnormal urination (2/8; 25%). At the time of initial evaluation, the mean serum or plasma creatinine was 451.72 ± 190.06 μmol/L (5.11 ± 2.15 mg/dL) and BUN was 18.84 ± 8.85 mmol/L (52.75 ± 24.77 mg/dL). Five horses (5/6; 83.3%) had either an increased number of red blood cells ( n = 4) or hemoprotein ( n = 1) in the urine. All horses were treated with IV isotonic, balanced crystalloids either as a bolus, continuous rate infusion, or a combination of the 2. Seven horses (7/8; 87.5%) survived the initial episode of AKI and 1 horse (1/8; 12.5%) was euthanized. Of the 7 surviving horses, 2 horses (2/7; 28.5%) went on to develop chronic renal dysfunction. Warmblood breeds were overrepresented in the AKI group ( P = 0.008; odds ratio: 11.5, 95% confidence interval: 1.8–72.1), when compared to horses that received bisphosphonates during the study period and did not develop AKI. Conclusions Bisphosphonate administration, with or without concurrent nonsteroidal anti‐inflammatory drugs, can be associated with AKI in horses. Serum creatinine should be monitored prior to and following bisphosphonate treatment to minimize this risk. Further evaluation of renal function is warranted in horses that develop clinical signs of poor appetite, lethargy, or altered urination in the days following bisphosphonate treatment.