title: Luteal function in mares following administration of oxytocin, cloprostenol or saline on day 0, 1 or 2 post-ovulation.
abstract: Mares (n = 30) were treated in the post-ovulatory period with saline, oxytocin, or cloprostenol (Clo). Dose, administration frequency and treatment day (Day 0, 1 or 2 post-ovulation) were evaluated. Interovulatory interval of control cycles was 22.7 (+/-0.36) days with a range of 20.6 (+/-1.44) to 23.8 (+/-1.39) days among all treatment groups. Mares treated with two micro-doses of cloprostenol on Day 2 post-ovulation had the shortest interovulatory interval. This group also had the lowest mean circulating progesterone concentrations on Days 3-7 and 13, and was the slowest group to reach concentrations of 5 ng/ml. Repeated administration of cloprostenol over 24 h in the early post-ovulatory period may more effectively impair luteal function than single doses. This could negatively affect pregnancy outcome but may be effective for lysing the early post-ovulatory luteal structure when mares are not bred.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5522, USA. niegary@earthlink.net
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Nie
authors.forename: Kristina E
authors.initials: KE
authors.lastname: Johnson
authors.forename: James G W
authors.initials: JG
authors.lastname: Wenzel
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Braden
mesh_terms: D000818:Animals; D003008:Cloprostenol / Q000008:administration & dosage*; D003338:Corpus Luteum / Q000187:drug effects* / Q000502:physiology; D030762:Estrous Cycle; D005260:Female; D006736:Horses / Q000502:physiology*; D010060:Ovulation; D010121:Oxytocin / Q000008:administration & dosage*; D011374:Progesterone / Q000097:blood; D013997:Time Factors
chemical_list: D003008:Cloprostenol; D011374:Progesterone; D010121:Oxytocin