Safety of omeprazole paste in foals and mature horses.

Omeprazole has been shown to promote healing of spontaneously occurring gastric ulcers in horses when administered for 28 days at a dose of 4 mg/kg bwt/day and to prevent recurrence of ulcers in almost all horses when treatment is continued at a dose of at least 2 mg/kg bwt/day. The purpose of the 3 studies reported here was to 1) evaluate the evolution of potential effects of omeprazole paste (GastroGard), at a dose of 20 mg/kg bwt/day (5x the recommended dose) for 91 days in mature Thoroughbred horses; 2) evaluate the safety in young horses of omeprazole paste when dosed at 4 mg/kg bwt/day (1x), 12 mg/kg bwt/day (3x) or 20 mg/kg bwt/day (5x) for 91 days in Tennessee walking horse foals; and 3) evaluate the safety of omeprazole paste when dosed at 40 mg/kg bwt/day (10x) for 21 days in mature Thoroughbred horses. Within each study, horses were allocated randomly to the control or omeprazole paste treatment group. Clinical examinations, serum biochemistry and haematology were performed at regular intervals until necropsy at the end of the study. There were no treatment-related clinical signs in any treated horse and serum biochemistry and haematology were normal. In conclusion, omeprazole paste is safe for use in horses as demonstrated in studies with foals and mature horses.