Some effects of multiple administration of detomidine during the last trimester of equine pregnancy.

Abstract

Detomidine was given to 11 pregnant mares at 3 week intervals during the last trimester of pregnancy. Maternal and fetal electrocardiographs were recorded and fetal activity studied by transabdominal ultrasonography, before and 2 h (2, 5, 10, 20, 30, 60, 90 and 120 min) after injection. After parturition, the foals were examined and weighed. Maternal and fetal heart rate showed an initial decline after detomidine administration. Maternal heart rate in the treatment group were lower already 2 min after injection, but a reduction in fetal heart was first seen 5 min after detomidine administration. Mean fetal heart rate at 2 min after detomidine injection was 109, 104, 95 and 90 beats/min, whereas at 5 min it was 80, 76, 72 and 66 beats/min in the 2nd, 3rd, 4th and 5th examination session, respectively. The heart rates did not revert to the control values during follow-up. Decline and recovery patterns were quite similar during all examination sessions. The mares exhibited conductive disturbances 2 min after detomidine administration, but fetal heart rhythm remained regular. Fetal activity was decreased at 5 min but had reverted to control values about 90 min after detomidine administration. Administration of detomidine (0.015 mg/kg) to healthy pregnant mares at 3 week intervals during the last trimester had no measurable detrimental effects on the outcome of pregnancy.