Objective—To describe the health status of foals derived by use of somatic cell nuclear transfer (NT) at a university laboratory.
Design—Retrospective case series.
Animals—14 live-born NT-derived foals.
Procedures—Medical records from 2004 through 2008 were evaluated to identify all pregnancies resulting in live-born NT-derived foals. Information obtained included gestation length, birth weight, foaling complications, gross abnormalities of the fetal membranes, appearance of the umbilicus, mentation of the foal, limb deformities, and any other abnormalities detected in the neonatal period. Clinicopathologic data were also evaluated when available. Records of 4 recipient mares during gestation were included.
Results—Six foals were clinically normal for all evaluated variables. The most common abnormalities detected in the remaining 8 foals included maladjustment, enlarged umbilical remnant, and angular deformity of the forelimbs. Two foals died within 7 days after parturition; in the remaining foals, these conditions all resolved with medical or surgical management. Large offspring syndrome and gross abnormalities of the fetal membranes were not detected. The 12 surviving foals remained healthy.
Conclusions and Clinical Relevance—Associated problems of calves resulting from use of NT have been reported, but there are few data on the outcome of foals resulting from adult somatic cell NT in horses. Although this population of foals had a lower perinatal mortality rate than has been reported for NT-derived calves, some NT-derived foals required aggressive supportive care. Birth of foals derived from NT should take place at a center equipped to handle critical care of neonates.
Case Description—3 sets of monozygotic twins resulting from transfers of single embryos to recipient mares were examined.
Clinical Findings—In all 3 recipient mares with twin pregnancies, only 1 embryonic vesicle was detected before day 25 of gestation. In 1 recipient mare, 2 apparent adjacent vesicles, each containing an embryo with a heartbeat, were visualized on ultrasonographic examination on day 37 of gestation. The other 2 recipient mares underwent ultrasonographic examination on day 30 of gestation, at which time only 1 vesicle and embryo was identified. In these latter 2 recipient mares, however, a thorough ultrasonographic examination for a second conceptus on day 30 had not been performed, as only 1 embryo had been transferred and visualized on early ultrasonographic examination.
Treatment and Outcome—All twin pregnancies resulted in death of both fetuses. Genetic analysis confirmed that each set of monozygotic twins originated from the transferred embryo.
Clinical Relevance—Monozygotic twin pregnancy may occur after embryo transfer; thus recipient mares should be examined thoroughly for multiple conceptuses, especially between 25 and 30 days of gestation. At this time, the allantoides of monozygotic twins should be visible ultrasonographically and effective management may still be possible.
Objective—To evaluate the efficiency of foal production following intracytoplasmic sperm injection (ICSI) and blastocyst culture of oocytes from mares that died or were euthanized under field conditions.
Design—Prospective case series.
Animals—16 mares (age, 3 to 19 years) that died or were euthanized for various causes.
Procedures—Ovaries were collected immediately before euthanasia (n = 10) or after death (6). Ovaries were transported to the laboratory for oocyte recovery (15 mares), or oocytes were recovered at a remote location and shipped to the laboratory (1). Oocytes underwent ICSI, and presumptive zygotes were cultured for 7 to 10 days. Blastocysts were shipped to embryo transfer facilities for transcervical transfer to recipient mares.
Results—Ovaries were processed 30 minutes to 12 hours (mean ± SD, 4.6 ± 3.3 hours) after mares' deaths. A mean of 14.1 ± 8.6 oocytes/mare were cultured, and 110 of 225 (49%) matured. Twenty-one blastocysts developed after ICSI and were transferred to recipient mares. Thirteen pregnancies were established; 10 healthy foals were produced from 6 donor mares. The number of blastocysts produced per mare and number of live foals produced per mare were significantly correlated with the number of oocytes recovered.
Conclusions and Clinical Relevance—Foals were produced from mares after death or euthanasia under field conditions. Proportions of foals born overall (10 foals/16 mares) and mares from which ≥ 1 foal was produced (6/16) were greater than those reported following recovery and oviductal transfer of oocytes to inseminated recipients after death of donor mares under field conditions.
To determine the effect of stage of estrus cycle (day after ovulation) at the time of transvaginal ultrasound-guided follicle aspiration (TVA) on parameters related to the success of in vitro equine embryo production.
14 healthy mares were used; 11 completed the study and were included for analysis.
Mares underwent TVA of all follicles ≥ 5 mm diameter at each of 3 timepoints: 7 days after ovulation, 14 days after ovulation, and S-DSF (subordinate to a dominant stimulated follicle), during estrus at 24 hours after gonadotropin administration. The 3 treatments were assigned to each mare in random order; mares underwent follicle growth and ovulation between treatments. Recovered oocytes were matured in vitro, subjected to intracytoplasmic sperm injection (ICSI), and cultured to the blastocyst stage in vitro.
Total follicle numbers differed significantly between individual mares but did not differ between treatments. The number of follicles of different sizes significantly (P < 0.05) differed between treatments, with mares in the Day 7 treatment having more follicles 5 to 9 mm in diameter and fewer follicles 20 to 24 mm in diameter than mares in the other 2 treatments. After in vitro maturation culture, there were significantly more mature oocytes in the S-DSF treatment than in the other 2 treatments. There were no differences in blastocyst rate after ICSI among treatment groups.
Timing of TVA for aspiration of S-DSFs may increase the number of mature oocytes available for ICSI. Understanding of the effects of timing of TVA will help veterinarians to maximize the efficiency of this procedure.