Determination of clinical and luteolytic effectiveness of a prostaglandin analog in mares by a dose response study.

In trials covering two seasons, 124 thoroughbred and 40 quarterhorse mares with either normal cycles (55 diestrous mares, 33 postpartum mares after foal heat) or in anestrus during the breeding season (76) were treated with either a novel PGF analog K 11941 or with the PGF analog prostalene (Synchrocept(trade mark)). K 11941 was used over a range of doses from 0.5 to 4.5 mg, while prostalene was applied at the recommended dose level of 2 mg. Blood progesterone determinations, clinical observations and the results of breeding confirmed that K 11941, at doses of 2 mg or larger, and prostalene, were effective and safe luteolysins; heat and ovulations occurred within the expected time intervals and fertility was satisfactory. Clinical data were converted into a response score (CRS) and an added fertility score (CRSF) for statistical evaluation and the establishment of a dose response curve. In both scores, 0.5 to 1.5 mg were significantly less effective than the higher dose levels (p<.0001). No significant differences were found for the 2 and 3 mg dose of K 11941 in diestrous and anestrous mares. In both indications, prostalene scored less (p<.05). Data analysis and establishment of a dose response curve point to 3 mg of K 11941 as the optimal dose.

Periovulatory changes in peripheral plasma progesterone and estrogen concentrations in the mare.

Concentrations of progesterone and estrogen were measured in peripheral blood plasma samples from mares around the time of ovulation. Samples were collected every 2 hours from 36 hours before, to 26 hours after, ovulation and assayed by radioimmunoassay. Progesterone concentrations were between 60 and 100 pg/ml for the period 24 hours before ovulation through 8 hours after ovulation. By 10 hours after ovulation, concentrations increased to 140 pg/ml and, by 26 hours after ovulation, reached 346 pg/ml. Plasma estrogen concentrations did not change significantly throughout the same period.

Influence of mare uterine tubal fluids on the metabolism of stallion sperm.

Three experiments were conducted on the metabolism of stallion sperm. In experiment 1, whole and washed sperm were incubated under aerobic and anaerobic enviroments and analyzed before and after controlled incubation for motility, pH, lactic acid, glucose, fructose, and O2 comsumption. In experiment 2, whole and washed sperm were incubated aerobically and anaerobically with and without uterine tubal fluids. Experiment 3 was the same as experiment 2, except added substrates of glucose and lactic acid were studied. The same examinations were made in experiments 2 and 3 as for experiment 1. Motility decreased significantly during incubation for all treatments, with the greatest decrease occurring for whole semen where only trace amounts of substrate (fructose) were present. Exogenous glucose plus uterine tubal fluid maintained sperm motility better than did added lactate. However, sperm respiration rates were highest when exogenous lactate was the only substrate in the incubation medium. The mean pH values for gel-free stallion semen at the start of controlled aerobic and anaerobic incubation were 7.08 and 7.34. Lactic acid accummulation for 1 hour increased from 0.05 mg to 0.09 mg/10(9) sperm when uterine tubal fluid was added to the incubation medium. Washed spermatozoa incubated in 0.03 M glucose plus uterine tubal fluid utilized less glucose than did sperm incubated in the glucose medium. These results, along with the increased oxygen utilization (ZO2) values produced by adding uterine tubal fluid to the incubation mediums, might indicate utilization of a uterine tubal substrate. Added uterine tubal fluid resulted in increased ZO2 values (expressed in mul of O2 utilized by 10(8) sperm in 1 hour at 37 C) for whole semen from 10.45 to 12.63. Washed spermatozoa also respired at a significantly greater rate than whole sperm. Respiration rates were greater for sperm incubated with 0.01 M lactic acid than for any other substrate or experiment.

Closure of ductus arteriosus determined by cardiac catheterization and angiography in newborn foals.

The physiologic closure of the ductus areteriosus was determined in 4 foals less than 16 hours old. The common carotid artery was catheterized, using local anesthesia and tranquilization, and contrast medium was injected into the ascending aorta. Radiographs were made of heart and great vessels during and after the injection to visualize the pathway of injected contrast medium.