SOME EFFECTS OF MULTIPLE ADMINISTRATIONS OF DETOMIDINE DURING THE LAST TRIMESTER OF EQUINE PREGNANCY

Detomidine was given to 11 pregnant mares at 3 week intervals during t he last trimester of pregnancy. Maternal and fetal electrocardiographs were recorded and fetal activity studied by transabdominal ultrasonog raphy, before and 2 h (2, 5, 10, 20, 30, 60, 90 and 120 min) after inj ection. After parturition, the foals were examined and weighed. Matern al and fetal hearts rate showed an initial decline after detomidine ad ministration. Maternal heart rate in the treatment group were lower al ready 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 89 beats/min, whe reas 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 rev ert to the control values during follow-up. Decline and recovery patte rns were quite similar during all examination sessions, The mares exhi bited conductive disturbances 2 min after detomidine administration, b ut fetal heart rhythm remained regular. Fetal activity was decreased a t 5 min but had reverted to control values about 90 min after detomidi ne administration. Administration of detomidine (0.015 mg/kg) to healt hy pregnant mares at 3 week intervals during the last trimester had no measurable detrimental effects on the outcome of pregnancy.