TITLE:
Effect of administration of phenylephrine immediately after low dose insemination on pregnancy rates in mares
AUTHORS:
Theresa Beachler, Renan Sper, C. Scott Bailey, James Shewmaker, C. Nick Buchanan, Anne Josson-Schramme, Michael Whitacre
KEYWORDS:
Artificial Insemination; Low Dose Insemination; Equine; Phenylephrine
JOURNAL NAME:
Open Journal of Obstetrics and Gynecology,
Vol.3 No.10,
December
13,
2013
ABSTRACT:
There
is considerable pressure on equine veterinarians to achieve good pregnancy
rates with very small doses of semen. Phenylephrine administration in the
rabbit increased numbers of oviductal, uterine, and cervical sperm, myometrial
contractions, and fertilized ova after low dose insemination. The use of
phenylephrine to enhance uterine contractility and fertility has not been
investigated in the mare. Thus, the objective of this study was to determine if
phenylephrine administration would result in clinically acceptable pregnancy
rates in mares bred by low dose insemination. The hypothesis (Ha) was that pregnancy
rates would be significantly higher in mares receiving phenylephrine compared
to saline controls. Six pony mares and eight horse mares were enrolled in this
study. Mares were inseminated within 24 hours of ovulation with 30 million
progressively motile spermatozoa from a single fertile stallion. Immediately
following insemination, mares were administered either phenylephrine (0.06
mg/kg) or 1mL of saline via IV injection. Pregnancy status was determined 14
days following ovulation via transrectal ultrasonography. Pregnancy rates in
phenylephrine treated mares were 44% (4/9) while 22% (2/9) in saline-treated
mares (P > 0.05).