Clinical and Endocrine Investigations after Dexamethasone and Prostaglandin Induced Premature Parturition – A Case Report

Sometimes it is necessary to induce abortion/ parturition in cattle. The most common methods are by injections of either PGF2α (or an analogue) or dexamethasone/ flumethasone. If the induction is performed too early in pregnancy the likelihood of achieving parturition or abortion is low. In an experiment where dexamethasone was used to induce parturition in heifers (Kask et al. 2000 ab, Königsson et al. 2001), one animal did not respond to the induction and this brief communication is based on that particular animal. The heifer (Swedish Red and White breed) received 2 injections of dexamethasone (Vorenvet® vet., Boehringer Ingelheim, GmbH, Ingelheim, Germany) at 2⁄2 weeks before expected term with a dose of 20 mg per injection, 24 h in between. Eleven days after the second injection of dexamethasone parturition had not yet occurred. At that time 25 mg prostaglandin F2α (Dinolytic® vet., Boehringer Ingelheim) was given intramuscularly and this was repeated 24 h thereafter. The general clinical status and occurrence of vaginal discharge were monitored daily until 7 weeks postpartum (PP). Rectal palpation for determining uterine tone and position were performed every third day starting on the day 5 PP. On the same days uterine content, measurements of the diameter of the cervix and uterine horns as well as resumption of the ovarian function were monitored by ultrasonography. Uterine biopsy samples were collected during 6 weeks postpartum for determination of elimination of uterine bacteria. Jugular vein blood samples for analysis of PGF2α metabolite were collected into heparinised Venoject tubes (Terumo Europé N.V., Leuven, Belgium) every hour starting immediately after first dexamethasone injection and was continued until the end of parturition. After parturition, collection frequency was decreased to 5 samples per day during 8 weeks PP. After centrifugation, about 5 ml of plasma were removed and stored at -20°C until hormone analyses were performed using a radioimmunoassay according to Granström & Kindahl (1982) for the PG-metabolite and an enhanced luminescence immunoassay (Amerlite®, Kodak Clinical Ltd, Amersham, England) for the progesterone. For progesterone analysis, 2 samples a day were selected. The duration of the PG reActa vet. scand. 2001, 42, 307-310.