P.L. Sertich

Ultrasonographic assessment of fetal well‐being during late gestation: development of an equine biophysical profile

Mares with complicated pregnancies (illness, problems at parturition or delivery of an abnormal foal, n = 30) were scanned transabdominally from 298 days gestation to term in order to measure fetal size, evaluate fetal well-being and characterise the intrauterine environment. The results of the last scan obtained prior to parturition were compared to normal data obtained from fetuses of comparable gestational age to develop a biophysical profile specific for the equine fetus. Twelve mares produced a normal foal (positive outcome) and 18 mares delivered 19 abnormal foals (negative outcome). Both fetuses that were inactive throughout the entire scan and 4 of 5 fetuses with heart rate abnormalities were abnormal at birth. Three of 4 fetuses surrounded by decreased allantoic fluid quantities had a negative outcome. All mares with large anechoic spaces between the uterus and placenta (n = 3) and/or thickened uteroplacental units (n = 5) delivered abnormal foals. There was a significant correlation between fetal aortic diameter and neonatal foal weight in these complicated pregnancies (P<0.0001, r = 0.85). Fetal aortic diameters were predicted from maternal weight and 6 fetuses had smaller than predicted aortic diameters, all with negative outcomes. A biophysical profile of the equine fetus from 298 days gestational age to term was developed that included 6 factors related to pregnancy outcome: fetal heart rate, fetal aortic diameter, maximal fetal fluid depths, uteroplacental contact, uteroplacental thickness and fetal activity. The profile proved informative about fetal well-being, perinatal morbidity and perinatal mortality. A low score was a definite indication of an impending negative outcome; however, a high score was not assurance of a positive outcome. The utility of such a biophysical profile and future directions for research are discussed.

Use of altrenogest to prepare ovariectomized mares as embryo transfer recipients.

Altrenogest was administered to ovariectomized mares to determine if treatment would enable establishment and maintenance of pregnancy after transfer of a 7-d embryo. Three different treatment regimens were used: Group A received 22 mg altrenogest daily starting 5 d before transfer, Group B received 66 mg altrenogest daily starting 6 days before transfer, Group C received 300 mg progesterone in oil intramuscularly daily starting 5 d before transfer. Intact, ovulation-synchronized recipients were used as controls for transfer technique. Pregnancy rates were 1 6 , 2 6 , 2 5 , and 13 19 for Group A, Group B, Group C, and controls, respectively. The pregnancy rate in Group A was significantly different from controls and Group A mares had poor uterine and cervical tone. These results show that ovariectomized mares treated with altrenogest are capable of establishing pregnancy after embryo transfer. Treatment with 22 mg altrenogest appears to be insufficient for optimal pregnancy rates after transfer in ovariectomized recipients.

Management strategies for mares at risk for periparturient complications

Perinatal death accounts for a large percentage of foal mortality. The most serious threats to perinatal survival remain septicemia, hypoxia, and dysmaturity. Topics discussed in this article include biochemical indices of fetoplacental function and evaluation and management of the high-risk mare.

Evaluation of biodegradable microspheres for the controlled release of progesterone and estradiol in an ovulation control program for cycling mares

Summary A series of experiments were conducted to examine the effectiveness of two formulations of progesterone and estradiol for use in an ovulation control program. The first formulation required daily injections of 150 mg progesterone and 10 mg of estradiol for 10 days combined with prostaglandin F2 alpha (PGF) on the last day of the regime. The second formulation used a new controlled release preparation consisting of microspheres made from a biocompatible, biodegradable polymeric excipient poly(DL-lactide) designed so that a single injection would deliver the entire dose of 1.5 g progesterone and 100 mg estradiol at a controlled rate for a duration of 12 to 14 days and was followed by 10 mg PGF 14 days later. All of the mares treated with either formulation responded with ovulation occurring 18 to 24 days (n=50) or 21 to 25 days (n=13) following the beginning of treatment for mares receiving the daily or single injection microsphere formulations, respectively. Because control of ovulation involves variability of response instead of mean response, Levenes test for equality of treatment variances was also used to examine treatment effects which were not different (P>0.05) for any of the endpoints studied. The length of estrus following treatment was not different (P>0.05) and averaged 5.3 and 4.7 days for mares receiving the daily injections or single injection formulations, respectively. The proportion of mares with a normal estrus of more than 2 days in duration also did not differ (P>0.05). Furthermore, because of the importance of mares responding to treatment with the occurrence of both estrus and ovulation together, a clinical response scoring system was used to measure the effectiveness of each of the treatments. Clinical response scores and the proportion of mares with clinical response score of 5 or above were not different (P>0.05). Lastly, conception rates for mares bred on the estrus after treatment were not different (P>0.05) and averaged 53% (8/15) for mares treated daily and 80% (4/5) for mares that received the controlled release formulation. These results indicate thatboth daily injections of progesterone and estradiol for 10 days or the use of the new controlled release formulation for steroid administration when followed by PGF at the end of the treatment period, provided reasonably precise control of fertile ovulations.

Retrospective study of dystocia in mares at a referral hospital.

REASONS FOR PERFORMING STUDY The period between the onset of dystocia and its resolution has an important bearing on fetal outcome. There are few published data on which to base decisions regarding optimum management of cases in practice. OBJECTIVES To evaluate and compare the effects of a coordinated dystocia management protocol (CDMP) with that of a previous protocol of random management on time to resolution and outcome in both an emergency dystocia referral population of mares (referred emergency cases: EM) and in a population of mares residing in hospital due to high risk pregnancy (HRP) concerns that then experience dystocia at parturition. METHODS Retrospective study performed at a university hospital referral centre of cases presenting from 1991-2004 divided into Group 1 (pre-CDMP) and Group 2 (CDMP). RESULTS Medical records of 71 cases with dystocia were retrieved and data recorded. For referred emergency cases (EM), time from hospital presentation to resolution decreased significantly by 32 min (P = 0.03) after institution of CDMP. Survival rate of mares at discharge was 86%. Survival of EM foals was low, with 10% in Group 1 and 13% in Group 2, surviving to discharge. For EM foals delivered alive, survival to discharge was 30% and 43% in Groups 1 and 2, respectively. Median Stage II was significantly (P < 0.001) different at 71 and 282 min for EM foals delivered alive vs. those not alive at delivery, respectively. Median duration of Stage II was also significantly (P < 0.001) different between EM foals surviving and not surviving to discharge, at 44 and 249 min, respectively. Survival of HRP dystocia foals to discharge was 79%. CONCLUSIONS Although CDMP reduced the time from presentation at the hospital to resolution significantly for EM, total duration of Stage II for EM was unchanged, as was foal outcome. POTENTIAL RELEVANCE Very early referral of mares with dystocia to referral centres with dystocia management protocols may improve fetal outcome as increased duration of Stage II in the horse affects fetal outcome negatively.

Sperm ultrastructure, morphometry, and abnormal morphology in American black bears (Ursus americanus)

The objective of this study was to describe sperm ultrastructure, morphometry, and abnormal morphology in American black bears. Electroejaculation was successful in 53.8% (7/13) of the attempts, but urine contamination was common. Epididymal sperm samples were also obtained from five bears. Sperm had a paddle-like head shape and the ultrastructure was similar to that of most other mammals. The most striking particularity of black bear sperm ultrastructure was a tightening of the nucleus in the equatorial region. Although the differences were not significant in all bears, the overall decrease in sperm nucleus dimensions during transport from the caput epididymis to the cauda suggested increasing compaction of the nucleus during maturation. For ejaculated sperm, nucleus length, width, and base width were 4.9, 3.7, and 1.8 μm, respectively, whereas sperm head length, width, and base width were 6.6, 4.8, and 2.3 μm, and midpiece, tail (including midpiece), and total sperm lengths were 9.8, 68.8, and 75.3 μm. Evaluation of sperm cytoplasmic droplets in the epididymis revealed that proximal droplets start migrating toward a distal position in the caput epididymis and that the process was mostly completed by the time sperm reached the cauda epididymis. The proportion of morphologically normal sperm in the ejaculate was 35.6%; the most prevalent sperm defects were distal cytoplasmic droplets and bent/coiled tails. The morphology of abnormal sperm and the underlying ultrastructural defects were similar to that in other large domestic animals thus suggesting similar underlying pathogenesis of specific sperm defects and similar effects on fertility.

24-Hour cooled storage of equine embryos

Equine embryos were collected by transcervical uterine flush 7 d after ovulation. The flush solution was Dulbeccos phosphate buffered saline (PBS) with 1% newborn calf serum and penicillin-streptomycin. Each embryo was washed in modified Dulbeccos PBS with 1% newborn calf serum and 0.4% bovine serum albumin, and placed in 4-ml polystyrene test tube containing this same medium. Embryos were packaged in a commercial semen transport container which cooled (-0.3 degrees C/min) and maintained the embryo at 4 to 6 degrees C. After 24 h, 16 embryos were transcervically transferred into recipient mares. Of the 16 embryos, six were detected as vesicles by ultrasonography at 14 d of pregnancy, of which three were carried to term and resulted in live, normal foals. Sixteen control embryos were directly transferred without prior storage and resulted in five foals.

Periparturient events in ovariectomized embryo transfer recipient mares

Ovariectomized mares treated with progesterone have established and maintained pregnancy after embryo transfer. This study evaluated the ability of ovariectomized embryo transfer recipients to successfully undergo parturition, raise a foal, and return to a useful reproductive status. Periparturient events in three ovariectomized embryo transfer recipient mares and three intact mares were compared. All mares foaled normally. Mammary scores were similar for both groups and all mares produced sufficient colostrum and milk to allow normal growth of healthy foals. Plasma progesterone levels decreased to < 5 ng/ml by Day 4 post partum in both groups. Progesterone concentrations continued to decrease and remained at <1 ng/ml in ovariectomized mares, but increased after the first postpartum ovulation (Day 9 to 15) in intact mares. Endometrial involution as determined by histological evaluation was complete in ovariectomized mares by Day 10 post partum and in intact mares by Day 11 post partum. As assessed by palpation per rectum and clearance of bacteria from the uterus, uterine involution was similar in all mares. The three ovariectomized mares subsequently received embryos by transcervical transfer and two of them established pregnancy. These results indicate that normal parturition, lactation, maternal behavior and uterine involution are independent of ovarian function.

Mid-gestation pregnancy is not disrupted by a 5-day gastrointestinal mucosal cytoprotectant oral regimen of misoprostol.

REASONS FOR PERFORMING STUDY To investigate effects of a 5-day oral misoprostol regimen recommended for use in horses as a gastrointestinal mucosal cytoprotectant during colic on mid-gestation pregnancies. OBJECTIVES To monitor cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as serum progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort of mid-gestation mares given a 5-day course of misoprostol or control treatment. METHODS Eleven light horse and pony mares with known breeding dates were administered 5 µg/kg bwt misoprostol orally, twice daily for 5 days. General health and pregnancy status were monitored daily during treatment via general physical examination, as well as palpation and ultrasonography per rectum of the uterus, cervix and conceptus. Jugular serum was obtained during and for 5 days following treatment for assay of progesterone and oestrone sulphate concentrations. Additionally, daily 12 h video samples of the mares were obtained to evaluate behaviour and comfort. RESULTS All findings, including cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort, were similar during misoprostol and control treatment. CONCLUSIONS Treatment of pregnant mares with a gastrointestinal mucosal cytoprotectant regimen of oral misoprostol for 5 days did not disrupt pregnancy, nor adversely affect the general health and comfort of these mares. Additional investigation of treatment at earlier and later stages of gestation, for longer-term treatment, as well as evaluating neonates for developmental disturbances, would add further information on safety of misoprostol during gestation. POTENTIAL RELEVANCE These results provide some assurance of safety of a 5-day gastrointestinal mucosal cytopretectant regimen of oral misprostol in mid-gestation pregnant mares.

Use of an immediate, qualitative progesterone assay for determination of day of ovulation in an equine embryo transfer program

An immediate, qualitative enzyme-linked immunosorbent assay (ELISA) for progesterone was evaluated for use in determining the day of ovulation in an equine embryo transfer program. Plasma samples were collected from 27 mares from the third day of estrus to the second day of diestrus for 50 cycles. Ovulation was detected by ultrasound examination per rectum. Plasma progesterone concentrations were estimated using the qualitative assay to detect the time of the rise in progesterone after ovulation. Qualitative scores were compared to progesterone concentrations for the same samples as measured by a quantitative ELISA; the correlation between the two methods, expressed as a contingency coefficient, was 0.56. The accuracy of determining day of ovulation using qualitative progesterone results was compared to that achieved using the quantitative assay or detection of the first day of diestrus by teasing. Accuracy in determining day of ovulation +/- 1 d using the three methods was qualitative, 36/50 (72%); quantitative, 44/50 (88%); and teasing, 43/50 (86%). There was a significant difference in accuracy between the qualitative and quantitative progesterone assays (P<0.05).