Clinical studies on daily low dose oxytocin in mares at term

The aim of this study was to test whether low dose oxytocin i.v. injection once a day to mares diagnosed as being ready for birth by mammary secretion calcium strip test measurements could be used as a reliable method to induce parturition and/or predict the mare would not foal during the following night if parturition did not occur within 2 h of treatment. Fifty-one near-term Haflinger mares were used and a single injection of 2.5 iu oxytocin was given between 1700 and 1900 h, including 10 mares used as controls which were administered a placebo. Administration of oxytocin resulted in the delivery of a normal foal within 120 min in 95% of mares. Twenty-four out of 38 (63%) treated animals foaled in response to the first oxytocin injection, 9 out of 38 (24%) in response to the second injection and 3 out of 38 (8%) in response to the third treatment. Two out of 38 (5%) treated mares foaled during the night irrespective of treatment whereas 7 out of 10 (70%) control mares foaled during the night. It was concluded that the major advantage of injecting a daily low dose of oxytocin appears to be that such a low dose induces delivery only in mares carrying a mature fetus and which are ready to foal.     

Ultrasound Measurements of the Dorsal Subarachnoid Space Depth in Healthy Trotter Foals during the First Week of Life

The aim of this study was to determine ultrasonographic measurements of the depth of the dorsal subarachnoid space in healthy foals so as to obtain reference values. The depth of the dorsal subarachnoid space was recorded in 50 trotter foals at day 1 (D1), 4 (D4), and 7 (D7) after birth, measuring the distance between the dura mater and the dorsal portion of the pia mater at the level of the cisterna magna, both in cross-sectional and longitudinal scans. Average, standard deviation, minimum and maximum values were calculated. Wilcoxon signed rank test was applied to verify data distribution. Analysis of variance (ANOVA) for repeated measurements and Bonferroni test as post hoc were applied to verify differences among D1, D4, and D7, both for cross-sectional and longitudinal scans. Student’s t-test for unpaired data was performed between fillies and colts to verify differences related to gender. Significance level was set at P < .05. Cross-sectional measurements were 7.2 ± 0.7 mm at D1, 7.4 ± 0.7 mm at D4, and 7.5 ± 0.6 mm at D7, whereas longitudinal measurements were 7.3 ± 0.6 mm at D1, 7.6 ± 0.6 mm at D4, and 7.6 ± 0.5 mm at D7. Differences in dorsal subarachnoid space depth were observed at D1 versus D7, both for cross-sectional and longitudinal scans, whereas no differences were found between fillies and colts. In this study, a reference range for the depth of the dorsal subarachnoid space has been reported in foals.     

Concentration of Lamellar Bodies and the Lecithin/Sphingomyelin Ratio in Equine Amniotic Fluid at the Time of Delivery

Veterinary Research Communications -     

Fertility at the first post partum estrous compared with fertility at the following estrous cycles in foaling mares and with fertility in nonfoaling mares

A retrospective study on the reproductive performance of 401 artificially inseminated trotter mares during six breeding seasons is presented. Mares, 279 post partum (PP) and 122 maiden and barren, or nonlactating (NL), were inseminated with fresh semen obtained from four fertile stallions of the same breed. Pregnancy rate (PR) of mares inseminated at the foal heat (182/253, 71.9%) was lower, but not significantly different, than the PR (22/26, 84.6%) of mares inseminated for the first time at the second post partum cycle and similar to the PR at the first and second cycle of NL mares (95/112, 77.8% and 25/33, 75.7%, respectively). PR of mares inseminated at the foal heat was higher, but nonsignificantly different, from PR of the post partum mares not pregnant after artificial insemination (AI) at foal heat and inseminated again at the following estrous cycle. The PR after AI at the foal heat was significantly higher than the PR when the AI was performed at the third or later cycle in NL mares (71.9% vs 22.2%, P<0.01). The estrus cycle/pregnancy ratio for the PP mares inseminated, for the first time at the foal heat or at the second heat and for NL mares was, respectively, 1.4, 1.2, 1.3 at first cycle and 1.4, 1.3 and 1.4 at the end of the season or when mares left the stud. The proportion of open mares at the end of the season or when leaving the stud was 7.1% (18/253), 3.8% (1/26) and 4.1% (5/122) for PP mares first inseminated at the first or second post partum cycle and for NL mares, respectively; the total rate of open mares was 6% (24/401). The foaling rate (FR) following conception at the foal heat (72.1%) was not statistically different from the FR following conception at any other cycle (50–100%). Based on the absence of significant differences in fertility at the first post partum estrus cycle versus any other estrus cycle, we conclude that breeding at the foal heat should be advisable.     

Ocular abnormalities in healthy Standardbred foals

Objective To determine the prevalence and describe ocular abnormalities in healthy Standardbred foals within 48 h of birth. Animals One hundred and two neonatal foals. Procedures All foals had an unassisted delivery. On the basis of physical examination and the results of hematological and biochemical parameters, all foals were unaffected by systemic diseases. A complete ophthalmic examination was performed within 48 h of birth. Foals with ocular hemorrhages were re‐examined weekly until the abnormalities were resolved. Results 65/102 (63.7%) foals did not show ocular abnormalities, while in 37/102 (36.3%) cases, ocular abnormalities were present. Retinal and subconjunctival hemorrhages were recorded in 19/102 (18.6%), and in 13/102 (12.7%), respectively. In 4/102 (3.9%) animals, an entropion of the lower eyelid was present. Only one foal (1%) showed a congenital nuclear unilateral cataract. No other ocular abnormalities were detected. However, all foals showed various degrees of remnants of hyaloid system. One week after the first ocular examination, retinal hemorrhages had resolved in 100% of the eyes, whereas subconjunctival hemorrhages had disappeared in all eyes by the second week following the first examination. Conclusions The acquired ocular lesions observed with relatively high frequency in the examined healthy Standardbred foals were ocular hemorrhages, which always showed a good outcome. Although these abnormalities were present at birth, they were not considered strictly congenital but likely acquired during parturition. Instead, congenital ocular abnormalities were rarely diagnosed, and the entropion of the lower eyelid was the most common disease in the breed.