Morphological study of equine amniotic compartment

Study on NGF and VEGF during the Equine Perinatal Period-Part 2: Foals Affected by Neonatal Encephalopathy

Neonatal Encephalopathy (NE) may be caused by hypoxic ischemic insults or inflammatory insults and modified by innate protective or excitatory mechanisms. Understanding the underlying pathophysiology is important in formulating a rational approach to diagnosis. The preliminary aim was to clinically characterize a population of foals spontaneously affected by NE. The study aimed to: (i) evaluate nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) levels in plasma samples obtained in the affected population at parturition from the mare’s jugular vein, umbilical cord vein and foal’s jugular vein, as well as in amniotic fluid; (ii) evaluate the NGF and VEGF content in the plasma of foals affected by NE during the first 72 h of life/hospitalization; (iii) evaluate NGF and VEGF levels at birth/admission in relation to selected mare’s and foal’s clinical parameters; (iv) evaluate the relationship between the two trophic factors and thyroid hormone levels (TT3 and TT4) in the first 72 h of life/hospitalization; and (v) assess the mRNA expression of NGF, VEGF and brain-derived neurotrophic factor (BDNF), and their cell surface receptors, in the placenta of mares that delivered foals affected by NE. Thirteen affected foals born from mares hospitalized for peripartum monitoring (group NE) and twenty affected foals hospitalized after birth (group exNE) were included in the study. Dosage of NGF and VEGF levels was performed using commercial ELISA kits, whereas NGF, VEGF, and BDNF placental gene expression was performed using a semi-quantitative real-time PCR. In group NE, NGF levels decreased significantly from T0 to T24 (p = 0.0447) and VEGF levels decreased significantly from T0 to T72 (p = 0.0234), whereas in group exNE, only NGF levels decreased significantly from T0 to T24 (p = 0.0304). Compared to healthy foals, a significant reduction of TT3 levels was observed in both NE (T24, p = 0.0066; T72 p = 0.0003) and exNE (T0, p = 0.0082; T24, p < 0.0001; T72, p < 0.0001) groups, whereas a significant reduction of TT4 levels was observed only in exNE group (T0, p = 0.0003; T24, p = 0.0010; T72, p = 0.0110). In group NE, NGF levels were positively correlated with both TT3 (p = 0.0475; r = 0.3424) and TT4 levels (p = 0.0063; r = 0.4589). In the placenta, a reduced expression of NGF in the allantois (p = 0.0033) and a reduced expression of BDNF in the amnion (p = 0.0498) were observed. The less pronounced decrease of the two trophic factors compared to healthy foals, their relationship with thyroid hormones over time, and the reduced expression of NGF and BDNF in placental tissues of mares that delivered affected foals, could be key regulators in the mechanisms of equine NE.

Study on NGF and VEGF during the Equine Perinatal Period-Part 1: Healthy Foals Born from Normal Pregnancy and Parturition

The importance of trophic factors, such as nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and brain-derived neurotrophic factor (BDNF) during the perinatal period, is now emerging. Through their functional activities of neurogenesis and angiogenesis, they play a key role in the final maturation of the nervous and vascular systems. The present study aims to: (i) evaluate the NGF and VEGF levels obtained at parturition from the mare, foal and umbilical cord vein plasma, as well as in amniotic fluid; (ii) evaluate NGF and VEGF content in the plasma of healthy foals during the first 72 h of life (T0, T24 and T72); (iii) evaluate NGF and VEGF levels at parturition in relation to the selected mares’ and foals’ clinical parameters; (iv) evaluate the relationship between the two trophic factors and the thyroid hormone levels (TT3 and TT4) in the first 72 h of life; (v) assess mRNA expression of NGF, VEGF and BDNF and their cell surface receptors in the placenta. Fourteen Standardbred healthy foals born from mares with normal pregnancies and parturitions were included in the study. The dosage of NGF and VEGF levels was performed using commercial ELISA kits, whereas NGF, VEGF and BDNF placental gene expression was performed using semi-quantitative real-time PCR. In foal plasma, both NGF and VEGF levels decreased significantly over time, from T0 to T24 (p = 0.0066 for NGF; p < 0.0001 for VEGF) and from T0 to T72 (p = 0.0179 for NGF; p = 0.0016 for VEGF). In foal serum, TT3 levels increased significantly over time from T0 to T24 (p = 0.0058) and from T0 to T72 (p = 0.0013), whereas TT4 levels decreased significantly over time from T0 to T24 (p = 0.0201) and from T0 to T72 (p < 0.0001). A positive correlation was found in the levels of NGF and VEGF in foal plasma at each time point (p = 0.0115; r = 0.2862). A positive correlation was found between NGF levels in the foal plasma at T0 and lactate (p = 0.0359; r = 0.5634) as well as between VEGF levels in the foal plasma at T0 and creatine kinase (p = 0.0459; r = 0.5407). VEGF was expressed in all fetal membranes, whereas NGF and its receptors were not expressed in the amnion. The close relationship between the two trophic factors in foal plasma over time and their fine expression in placental tissues appear to be key regulators of fetal development and adaptation to extra-uterine life.

Dystocia in the Standardbred Mare: A Retrospective Study from 2004 to 2020

Dystocia as a prolonged stage II parturition (>30 min) was associated with a higher risk of complications. The hypothesis of the study was that any type of dystocia could affect the foal’s health, even when the stage II was <30 min. Clinical reports on 222 Standardbred mares and their foals hospitalized at the Veterinary Teaching Hospital of the University of Bologna from 2004 to 2020 were reviewed. Mares were divided into the Eutocia Group (165, eutocic delivery) and the Dystocia Group (57, dystocic delivery). The incidence of dystocia was 4.9%. Stage II was longer in the Dystocia Group (median 20 min) than in the Eutocia Group (median 12 min). All occurrences of dystocia were retrospectively classified into three categories of severity: mild, moderate and severe dystocia. The occurrence of postpartum complications in mares and neonatal diseases and failure of passive transfer of immunity in foals was higher in the Dystocia Group. Foal venous lactatemia and serum creatine kinase were significantly higher in the Dystocia Group (median 3.9 mmol/L; 262 UI/L respectively) than in the Eutocia Group (median 3.1 mmol/L; 187 UI/L respectively). The APGAR score was lower in the Dystocia Group (median 8) than in the Eutocia Group (median 10) and significantly lower in severe dystocia (median 3). The duration of stage II should not be considered the only parameter of dystocia in mares: even a rapid resolution of dystocia could pose health risks to the foal and the mare.

Physical activities and morphologic aspects of the equine fetus during Days 40 to 150

Intrauterine mobility of the fetal-amniotic unit is unique in equids among domestic species. Intrinsic activity begins as head nods on ∼ Day 40 (Day 0 = ovulation) and by Day 60 has progressed into intermittent subtle to vigorous head, neck, limb, and body movements. On Days 60-100, fetal mobility is maximal with traveling of the fetal-amniotic unit throughout an allantoic pool that encompasses the uterine horns and uterine body. The fetus may be entirely within one uterine horn with the horn entrance closed behind it, and then may work through the entrance into the uterine body. Mobility gradually decreases after Day 100 with a decrease in relative quantity of allantoic fluid but intrinsic activity continues. Changes in each of fetal intrauterine location, presentation, and recumbency can occur frequently (e.g., 5-min intervals). About 80% of fetal mobility is from the propulsive effects of intrinsic fetal activities, and the remainder is from currents and shifts in the allantoic pool. The fluid currents are attributable to transient uterine constrictions that vary from 10 mm in width to the length of a uterine horn and to extrinsic mare and adjacent visceral activity. The fetus is tethered by a long umbilical cord attached at the mid-uterus allowing travel throughout an allantoic sac that involves the entire uterus. The mobile fetus seemingly practices the neuromuscular coordination that it will need during independent life. The theriogenologist can educate and fascinate onlookers by ultrasound demonstrations of bursts of fetal activity and mobility. An online video is included.