Oxitocina

In:  53rd Annual Convention of the American Association of Equine Practitioners - AAEP, 2007 - Orlando, FL, USA,   (Ed.). Publisher: American Association of Equine Practitioners, Orlando, FL.Internet Publisher: International Veterinary Information Service, Ithaca NY (www.ivis.org), Last updated: 5-Dec-2007; P81108.1207
Use of Exogenous Oxytocin to Block Luteolysis in Mares: A Plausible Methodof Long-Term Suppression of Estrus
D. Vanderwall1, D. M. Rasmussen2 and G. L. Woods3
1,2,3Northwest Equine Reproduction Laboratory, University of Idaho, Moscow, ID, USA.
Intramuscular administrationof 60 units of oxytocin twice daily on days 7 to 14 post-ovulation blocked luteolysis and induced prolonged corpora luteal function in 6 of 6 mares compared to 0 of 6 control mares treated withsterile saline. Mares with prolonged luteal function maintained progesterone levels >1.0 ng/ml continuously through day 30 post-ovulation, while all of the control mares underwent luteolysis by day 16post-ovulation. Progesterone levels >1.0 ng/ml inhibit estrous behavior; therefore, disrupting luteolysis by administering exogenous oxytocin appears to be a plausible and practical method oflong-term suppression of estrus in mares.
1. Introduction
The objective of this study was to determine if IM administration of exogenous oxytocin twice daily on days 7 - 14 post-ovulation would blockluteolysis and prolong corpora luteal function in mares.
2. Materials and Methods
Blood samples were collected every other day from day 0 (ovulation) until day 40. On day 7, mares were assigned to oneof two groups (n = 6/group). Group 1 was the saline-treated control mares, and group 2 was the oxytocin-treated mares. Beginning on day 7, control mares received 3 ml sterile saline (q 12 h, IM), andoxytocin-treated mares received 60 USP units oxytocin (q 12 h, IM) through day 14. Mares were considered to have prolonged luteal function if progesterone levels remained >1.0 ng/ml continuously...