Preliminary evaluation of ionized magnesium levels in dogs on long-term esomeprazole administration

To investigate the level of whole-blood ionized magnesium (iMg) in dogs with long-term use of proton pump inhibitors (PPIs). The study included 10 client-owned dogs with esomeprazole administration over 6 months and 62 healthy dogs to determine de novo reference interval (RI) of iMg. Dogs that received esomeprazole for 6 months or longer were retrospectively reviewed to determine the incidence of hypo- or hypermagnesemia based on the de novo RI. Additionally, the iMg levels from the study group were compared with those of 20 age-, sex-, and body weight-matched controls from the 62 dogs. The median (range) duration of esomeprazole usage was 26 months (6 to 94). The de novo RI for iMg was determined as 0.73 (90% CI, 0.58 to 0.87) to 1.43 mg/dL (90% CI, 1.33 to 1.46). Based on the RI, none of the dogs with long-term esomeprazole developed hypo- or hypermagnesemia. The iMg from the matched control group was 1.17 mg/dL (90% CI, 0.83 to 1.46). The lowest iMg after 6 months of esomeprazole administration (90% CI, 0.96 mg/dL, 0.87 to 1.41) was significantly lower than the control group (P = .031). The iMg measured at the end of long-term esomeprazole treatment was 1.03 mg/dL (90% CI, 0.87 to 1.41) and not significantly different from the control group (P = .179). Ionized hypomagnesemia was not observed after long-term use of esomeprazole in the small number of dogs included in this study. Robust RI needs to be determined in future studies to investigate the incidence of hypomagnesemia in dogs with long-term use of PPIs. Future studies in a larger number of dogs are warranted to confirm the findings from the present study and to determine whether the long-term use of esomeprazole in dogs is at risk of developing ionized hypomagnesemia.