Effect of administration of phenylbutazone or progesterone on recovery of embryos from the uterus of mares 5 days after ovulation.

The research investigates how administering phenylbutazone or progesterone affects equine embryo recovery from the uterus five days after ovulation, finding that neither treatment increases embryo recovery compared to controls.

Methodology

• The authors used twelve horse mares for the study.
• They divided the mares into four groups (A, B, C, D), each receiving different treatments:
  • Group A (controls): Uterine flush done seven to eleven days after ovulation.
  • Group B (five-day controls): Uterine flush performed five days after ovulation.
  • Group C: Uterine flush done five days after ovulation, post administration of phenylbutazone on day three.
  • Group D: Uterine flush performed five days after ovulation, post administration of progesterone on days zero, one, and two.
• Each mare was randomly assigned to each group on a one-time basis.

Findings

• The number of embryos recovered from each group were as follows:
  • Group A: 13 embryos from 12 mares.
  • Group B: 3 embryos from 12 mares.
  • Group C: 4 embryos from 11 mares.
  • Group D: 1 embryo from 11 mares.
• The study found that three of the twelve nontreated mares had embryos enter the uterus before day six, indicating early entry might not be uncommon.
• Most critically, the authors noted that neither phenylbutazone nor progesterone increased the number of embryos recoverable from the uterus on day five, compared to the five-day control group.

Conclusions

The study demonstrated that the administration of phenylbutazone or progesterone does not appear to increase the recovery rate of embryos from the uterus of mares on the fifth day after ovulation. This suggests these treatments may not be effective strategies for influencing uterine tubal motility and consequently the timing of embryo entry into the uterus.