Healthy Foals Research Articles

Effect of plasma transfusion on serum amyloid A concentration in healthy neonatal foals and foals with failure of transfer of passive immunity.

Anecdotal evidence suggests plasma transfusions increase serum amyloid A (SAA) concentrations in healthy neonatal foals making this marker of inflammation inappropriate for therapeutic decision making in such animals. Administration of hyperimmune fresh frozen plasma (FFP) increases SAA concentration in healthy foals and in foals with failure of transfer of passive immunity (FTPI). Eighty-six healthy foals. Prospective cohort study. Foals <24 hours of age receiving plasma transfusion for treatment of FTPI (serum immunoglobulin G [IgG] concentrations <8g/L; n=17) or as a preventative measure for Rhodococcus equi infection (IgG >8g/L; n=33) were enrolled. A healthy nontransfused group of foals (IgG >8g/L; n=21) also was included. SerumamyloidA concentration was determined before (t0h) and after (t24h) administration of FFP. Changes in blood SAA concentration were assessed using linear regression models. No statistical differences were found in SAA concentration at t0h or t24h among the 3 groups (P > .05, for all comparisons). The variation in SAA concentration before (t0h) and after (t24h) plasma transfusion showed that administration of FFP was not associated with the changes in SAA concentration (P > .05). An association between SAA concentration at t0h and at 24 hours (P < .05) was identified, where foals with higher SAA concentration at t0h also had higher SAA concentration at t24h. Administration of FFP to newborn foals was not associated with changes in SAA concentration.

Impact of sedation, body position change and continuous positive airway pressure on distribution of ventilation in healthy foals.

This study aimed to compare the distribution of ventilation measured by electrical impedance tomography (EIT), in foals under varying clinical conditions of sedation, postural changes, and continuous positive airway pressure (CPAP). To support the interpretation of EIT variables, specific spirometry data and F-shunt calculation were also assessed. Six healthy Thoroughbred foals were recruited for this sequential experimental study. EIT and spirometry data was recorded: (1) before and after diazepam-sedation, (2) after moving from standing to right lateral recumbency, (3) in dorsal recumbency during no CPAP (CPAP0) and increasing levels of CPAP of 4, 7, and 10 cmH2O (CPAP4, 7, 10, respectively). Ventral to dorsal (COVVD) and right to left (COVRL) center of ventilation, silent spaces, tidal impedance variation, regional ventilation distribution variables and right to left lung ventilation ratio (R:L) were extracted. Minute ventilation was calculated from tidal volume (VT) and respiratory rate. F-Shunt was calculated from results of arterial blood gas analysis. Statistical analysis was performed using linear mixed effects models (significance determined at p < 0.05). (1) Respiratory rate was lower after sedation (p = 0.0004). (2) In right lateral recumbency (compared to standing), the COVVD (p = 0.0012), COVRL (p = 0.0057), left centro-dorsal (p = 0.0071) and dorsal (p < 0.0001) regional ventilation were higher, while the right ventral (p = 0.0016) and dorsal (p = 0.0145) regional ventilation, and R:L (p = 0.0017) were lower. (3) Data of two foals for CPAP10 was excluded from statistical analysis due to prolonged apnea. Stepwise increase of CPAP led to increases of COVVD (p = 0.0028) and VT (p = 0.0011). A reduction of respiratory rate was detected with increasing CPAP levels (p < 0.0001). (1) In healthy foals, diazepam administration did not alter distribution of ventilation or minute ventilation, (2) lateral recumbency results in collapse of dependent areas of the lung, and (3) the use of CPAP in dorsal recumbency at increasing pressures improves ventilation in dependent regions, suggesting improvement of ventilation-perfusion mismatch.

Vitamin E depletion is associated with subclinical axonal degeneration in juvenile horses.

Phosphorylated neurofilament heavy, a marker of neuroaxonal damage, is increased in horses with equine neuroaxonal dystrophy. However, the temporal dynamics of this biomarker during the post-natal risk period are not understood. To measure serum and cerebrospinal fluid phosphorylated neurofilament heavy concentrations in juvenile foals across the post-natal window of susceptibility for equine neuroaxonal dystrophy. Case-control in vivo experimental study. Concentrations of phosphorylated neurofilament heavy were measured using frozen serum and cerebrospinal fluid collected from 13 foals raised in a vitamin E deficient environment from 1 to 6months of age. Four of these foals were produced by equine neuroaxonal dystrophy-affected dams, developed clinical signs consistent with equine neuroaxonal dystrophy and had a diagnosis confirmed by histopathology. The remaining nine foals, produced by healthy mares, were vitamin E depleted and remained clinically healthy. An additional cohort of foals, produced by healthy mares, were supplemented with vitamin E (α-tocopherol; α-TOH) from birth and sampled similarly. Serum α-TOH concentrations were significantly higher in vitamin E supplemented healthy foals. Serum phosphorylated neurofilament heavy concentrations did not differ significantly between groups at any time point. Cerebrospinal fluid phosphorylated neurofilament heavy concentrations increased with age in healthy vitamin E depleted foals (p < 0.001); an effect that was not observed in healthy vitamin E supplemented foals. A genetically susceptible cohort supplemented with vitamin E was not available for comparison. We demonstrate that vitamin E depletion may elevate cerebrospinal fluid phosphorylated neurofilament heavy in otherwise healthy juvenile foals by 6 months of age. We highlight an important cofactor to consider when interpreting cerebrospinal fluid phosphorylated neurofilament heavy concentrations in juvenile horses.

The hypothalamic-pituitary-adrenal axis response to ovine corticotropin-releasing-hormone stimulation tests in healthy and hospitalized foals.

The hypothalamic-pituitary-adrenocortical axis (HPAA) response to sepsis can be impaired in critical illness. Corticotropin-releasing hormone (CRH) stimulation test might assess HPAA function in foals. To evaluate plasma cortisol, ACTH, arginine vasopressin (AVP), and endogenous CRH (eCRH) response to different doses of ovine CRH (oCRH). Healthy (n=14) and hospitalized (n=15) foals <7 days of age. In this prospective randomized study, oCRH (0.1, 0.3, and 1μg/kg) was administered intravenously and blood samples were collected before, 15, 30, 60, and 90 minutes after administration of oCRH to determine plasma hormone concentrations. The hormonal response was evaluated as the difference (Delta; μg/dL or pg/mL) or percent change between baseline hormone concentration and each time point after oCRH stimulation. Cortisol concentrations increased from baseline at 15 minutes with 0.1 and 0.3μg/kg and at 30 and 60 minutes from baseline with 1μg/kg oCRH (P < .05) in healthy and hospitalized foals. ACTH concentrations increased from baseline at 15 minutes with 0.1μg/kg and at 30 minutes with 1μg/kg oCRH (P < .05) in hospitalized foals. Delta cortisol 0 - 30, ACTH 0 - 30, and eCRH 0 - 30 was higher for the 1μg/kg compared with 0.1μg/kg oCRH in healthy foals (P < .05). Delta ACTH 0 - 15 and eCRH 0 - 30 was higher for the 1μg/kg compared with the lower doses of oCRH in hospitalized foals (P < .05). Cortisol, ACTH, and eCRH concentrations increased in response to administration of all doses of oCRH. One microgram per kilogram of oCRH appears to be optimal for the assessment of HPAA in healthy and hospitalized foals.

Comparison of serum iron status in healthy foals and foals with bronchopneumonia

Comparison of serum iron status in healthy foals and foals with bronchopneumonia

Red cell distribution width values and red cell distribution width-to-platelet ratio in Thoroughbred foals in the first 24hours of life.

To report red cell distribution width (RDW) values, to calculate RDW-to-platelet ratio (RPR), and to investigate a possible correlation of RDW and RPR index values in neonatal foals classified as healthy or at risk based on clinical information from a population of foals up to 24hours of life. Retrospective study conducted from records and CBCs of foals born between June and November from 2018 to 2020 foaling seasons. Breeding farm. Three hundred and nine neonatal full-term Thoroughbred foals. None. Foals were evaluated by a veterinarian within 15minutes after birth, and a blood sample was collected within 24hours of life. Based on clinical information, 88 of 309 foals (28.4%) were considered at risk of perinatal disease, and 201 were healthy. Mean gestational age for the foals was 346.3±9.7days. RDW values did not differ between groups. Gestational length demonstrated to have a negative correlation with RDW (r=-0.156, P=0.005) and mean corpuscular volume (r=-0.135, P=0.01), indicating a link of these variables to foal maturity. RPR index was higher for at-risk (0.073±0.018) than for healthy foals (0.068±0.014, P=0.01). RPR might be a promising early indicator of disease for the field triage of neonatal foals.

Assessment of the microvascular perfusion using sidestream dark‐field imaging in healthy newborn foals

Different methods to measure tissue perfusion are available in equine neonatology, but they are not representative of microvascular derangements. To evaluate the feasibility of the sidestream dark-field (SDF) capillaroscopy to visualize the capillary microvasculature in conscious newborn foals, the differences between two imaging sites and times of measurements, and the measurements' reproducibility. Seventeen healthy newborn foals were enrolled. Three sites at the upper and lower lip mucosa were assessed by SDF, using a hand-held capiscope, at 24 h and at 4-5 days after birth. Videos were assessed independently by two observers for quality and for semiquantitative calculation of microvascular parameters, including vascular density (VD), microvascular flow index (MFI), proportion of perfused vessels (PPV), and functional capillary density (FCD). Data were analyzed using unpaired and paired Student's T-tests to assess differences between sites and time-points. Bland-Altman plots and intraclass correlation coefficient (ICC) were used to assess measurement reproducibility. Differences were found between the upper and the lower lip for VD at both 24 h and 4-5 days, and for FCD at 24 h, and between the two time-points for PPV at the lower lip. ICC for measurement reproducibility was good for all parameters (0.64-0.79) for the lower lip, and was good for VD and FCD (0,76-0,79) and fair to moderate for MFI and PPV (0.31-0.41) for the upper lip. Measurement of the capillary microvasculature is feasible in the conscious newborn foal. The lower lip has the best measurement reproducibility. Further investigations are warranted in cardiovascularly compromised cases, particularly in septic foals.

The fecal bacterial microbiota of healthy and sick newborn foals

The fecal bacterial microbiota of normal foals and foals with enterocolitis has been characterized using next-generation sequencing technology; however, there are no reports investigating the gut microbiota in foals hospitalized for other perinatal diseases. To describe and compare the fecal bacterial microbiota in healthy and sick foals using next-generation sequencing techniques. Hospitalized (17) and healthy foals (21). Case-control study. Fecal samples were collected from healthy and sick foals on admission. Sick foals were further divided into sick nonseptic (SNS, n=9) and septic (n=8) foals. After extraction of DNA, the V4 region of the 16 S rRNA gene was amplified using a PCR assay, and the final product was sequenced with an Illumina MiSeq. Diversity was significantly lower in healthy than sick foals (P < .05). The bacterial membership (Jaccard index) and structure (Yue & Clayton index) of the fecal microbiota of healthy, septic, and SNS foals were similar (AMOVA, P > .05). Bacterial membership (AMOVA, P=.06) and structure (AMOVA, P=.33) were not different between healthy and sick foals. Enterobacteriaceae, Enterococcus, and Streptococcus were among the 5 more abundant taxa identified in both groups. Higher fecal microbiota diversity in sick than healthy foals might suggest a high exposure to environmental microorganisms or an unstable colonic microbiota. The presence of microorganisms causing bacteremia in foals in a high relative abundance in the feces of foals suggests the intestine might play an essential role in the causation of bacteremia in foals.

Transient increases in glutamate dehydrogenase (GLDH) activity occur in neonatal foals.

Liver analyte measurement is important in the evaluation of sick animals. Liver injury in horses is recognized by increased glutamate dehydrogenase (GLDH), sorbitol dehydrogenase (SDH), and aspartate aminotransferase (AST) activities, whereas biliary pathology is identified by increased alkaline phosphatase and γ-glutamyl transferase (GGT) activities or bilirubin concentrations. We have observed high GLDH, but not SDH, activities in neonatal foals admitted for conditions other than liver disease. Only one previous study have evaluated GLDH activity over time in healthy neonatal foals; however, SDH activity was not measured. We aimed to evaluate changes in liver analytes in neonatal foals over time. We measured serum liver analytes (GLDH, SDH, GGT, AST, total, direct, and indirect bilirubin) and creatine kinase activity of 11 clinically healthy foals before and at various times after suckling until 46 days of age. Analytes were also measured in colostrum and mare serum. Median GLDH activities increased after birth to peak at 3-4 days of age (106 U/L, reference interval, 0-8U/L). Median SDH activities had a lower peak at 3-4 days (15 U/L, reference interval, 0-11 U/L) and were frequently discordant with GLDH. There was no association between foal and mare serum or colostral enzyme activities. AST activity plateaued at 5-6 days, whereas GGT activity and total and indirect bilirubin concentrations peaked at 14 and 3-4 days of age, respectively. Transient increases in GLDH, SDH, and GGT activities and total and indirect bilirubin concentrations occur in clinically healthy neonatal foals and do not necessarily indicate relevant liver disease.

Changes in serum total protein and immunoglobulin G concentrations and Brix percentages in neonatal Arabian foals from birth up to 21 days of age

The aim of this study was to evaluate changes in the serum immunoglobulin G (IgG) and serum total protein (STP) concentrations and serum Brix percentages of neonatal Arabian foals during first 3 weeks of life. Blood samples were collected from 12 apparently healthy foals by jugular venipuncture at birth and at 12-hours, 24-hours, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15 and 21 days of age. Serum IgG and STP concentrations and Brix percentages were measured by the radial immunodiffusion assay, and digital STP and Brix refractometers, respectively. Based on the serum IgG concentrations measured at 24 h, two foals were diagnosed with failure of transfer of passive immunity (FTPI). While IgG concentrations were determined using the data of foals with adequate transfer of passive immunity, other calculations were made using the data of all foals. The mean IgG concentration of the foals increased from birth (<200 mg/dl) to 12 (2068.5 mg/dl) and 24 h (2184.7 mg/dl), and progressively decreased up to 21 days of age (1318.5 mg/dl). The serum IgG concentrations at 12 h were highly correlated with each of the IgG concentrations measured over the 21-day period. The serum IgG and STP concentrations and Brix percentages of the foals diagnosed with FTPI at 12 h did not reach the adequate strata over time. These results suggest that foals can be reliably tested for passive immunity status at 12 h after birth.

Plasma metabolome of healthy and Rhodococcus equi-infected foals over time.

Foals that develop pulmonary ultrasonographic lesions on Rhodococcus equi (R. equi) endemic farms are treated with antibiotics because those at risk of developing clinical pneumonia (~20%) cannot be recognised early. Candidate biomarkers identified using metabolomics may aid targeted treatment strategies against R. equi. (1) To describe how foal ageing affects their plasma metabolome (birth to 8 weeks) and (2) to establish the effects that experimental infection with Rhodococcus equi (R. equi) has on foal metabolome. Experimental study. Nine healthy newborn foals were experimentally infected with R. equi as described in a previous study. Foals were treated with oral antibiotics if they developed clinical pneumonia (n=4, clinical group) or remained untreated if they showed no signs of disease (n=5, subclinical group). A group of unchallenged foals (n=4) was also included in the study. By the end of the study period (8 weeks), all foals were free of disease. This status was confirmed with transtracheal wash fluid evaluation and culture as well as thoracic ultrasonography. Plasma metabolomics was determined by GC-MS weekly for the study duration (8 weeks). Foals' plasma metabolome was altered by ageing (birth to 8 weeks) and experimental infection with R. equi as demonstrated using multivariate statistical analysis. The intensities of 25 and 28 metabolites were altered by ageing and infection (p < 0.05) respectively. Furthermore, 20 metabolites changed by more than 2-fold between clinical and subclinical groups. The number of foals is limited. Foals were experimentally infected with R. equi. Ageing and R. equi infection induced changes in the plasma metabolome of foals. These results provide an initial description of foal's plasma metabolome and serve as background for future identification of R. equi pneumonia biomarkers.

The Influence of Age and Gender on the Serum XOR Activity, Leukocyte Gene Expression of XOR and MPO, and Biochemical Parameters in Newborn Foals

One of the initial responses of the host's innate immunity of newborns against pathogens is the use of oxidative enzymes. This study aimed to evaluate changes in serum xanthine oxidoreductase (XOR) activity, the leukocyte myeloperoxidase (MPO) and XOR genes expression, and some biochemical parameters in healthy Darehshuri newborn foals up to 60 days of life. Blood samples were collected from 16 foals at 1, 7, 15, 30, and 60 days and used for detecting XOR activity, biochemical parameters, and also gene expression by real-time RT-PCR. High activity of XOR was observed at birth, explained by physiologic hypoxia during the birth without sex difference. The significant decrease in XOR activity during the following days is probably related to the decreased levels of substrate and feedback inhibition of XOR by uric acid. No correlations were found between XOR activity and uric acid. A positive correlation was observed between XOR mRNA and serum XOR activity in 15 days. The results also indicate higher levels of MPO gene expression at 30 days, which may be associated with their capacity for neutrophil phagocytosis. The concentrations of creatinine, total protein, and albumin were higher at birth, whereas uric acid level was lower (P < 0.05). It can be concluded that XOR activity decreases with age and there is no significant change in its gene expression and MPO expression increases with age and is sex-dependent. There is an influence of age on XOR activity, leukocyte expression of MPO, and biochemical parameters in healthy newborn foals up to 60 days of life.

High-Risk Pregnancy Is Associated With Increased Alpha-Fetoprotein Concentrations in the Amniotic Fluid and Foal Plasma

This study aimed to determine alpha-fetoprotein (AFP) concentrations in amniotic fluid, plasma of mares and respective foals: carrying normal pregnancies and delivering healthy foals (n = 20; Group 1); carrying apparently normal pregnancies and delivering sick foals (n = 15; Group 2); carrying high-risk pregnancies and delivering sick foals (n = 14; Group 3). High-risk pregnancy was defined by a history of premature udder development/lactation or increased of the combined thickness of the uterus and placenta, or vulvar discharge and/or mares' systemic illness. Sick foals were affected by neonatal encephalopathy, sepsis, prematurity/dysmaturity, or hypoxic-ischemic encephalopathy. Based on histological examination of the chorioallantois, AFP trend was analyzed in pregnancies with pathologic (PFM) and normal fetal membranes (NFM). Concentrations of AFP were measured using a commercially available immunoassay previously validated for horses. Mares' plasma AFP did not change during the last 15–20 days of pregnancy in the three groups, and there was no difference among them. Amniotic fluid AFP was higher in Group 3 (P = .014). Foals’ plasma AFP concentration was higher from birth to 72hours in foals of Group 2 and 3 than in healthy ones, and foals of Group 3 had the highest value. The strong association (r = 0.84; P < .0001) between AFP in amniotic fluid and foals' plasma at birth is likely due to the presence of AFP in fetal urine. AFP was higher in pregnancy with PFM than with NFM in mare's plasma at admission (P = .031), amniotic fluid (P = .004), foal's plasma at birth (P = .002), at 24 (P = .005) and at 72 hours of life (P = .004). AFP is higher in pregnancy with histopathological lesions of the chorioallantois providing the evidence of the differences between pregnancy with a normal placental barrier and the more compromised ones. The increased AFP concentration in the amniotic fluid and plasma of high-risk foals suggests upregulation.

Plasma ascorbic acid, antioxidant capacity, and reactive oxygen species in healthy foals.

To describe ascorbic acid (AA) concentrations, plasma antioxidant capacity (PAC) and markers of oxidative stress, as measured by derivatives of reactive oxygen metabolites (dROMs), in healthy foals at birth and during the first month of life. Venous blood samples were collected from healthy Standardbred (n = 13) and Quarter Horse (n = 10) foals. Plasma AA, PAC, and dROMs were assessed at 3 to 12 hours, 3 days, and 1, 2, and 4 weeks of age. AA was measured via high-performance liquid chromatography. PAC and dROMs were measured with a free radical analytical system. Comparisons of AA, PAC, and dROMs at different time points were assessed. Mean ± standard deviation AA concentrations at 3 to 12 hours (44.7 ± 19.6 μmol/L; P ≤ .01), 1 (48.6 ± 22.5 μmol/L; P ≤ .001), and 2 weeks (41.8 ± 15.8 μmol/L; P ≤ .001) were higher than at 4 weeks of age (28.5 ± 12.7 μmol/L). Both PAC and dROMs significantly increased at different time points compared to 3 to 12 hours of age. Healthy foals have higher plasma AA concentrations shortly after birth, which then gradually decrease throughout the first month of life, suggesting that AA may represent a key antioxidant in the postnatal period. The concurrent increase in PAC and dROMs suggests that dynamic development of oxidative balance occurs after birth in foals. Development of AA, PAC, and dROM reference ranges in healthy foals could be used to guide therapeutic interventions and monitor during disease states characterized by increased oxidative stress.

Longitudinal assessment of adrenocortical steroid and steroid precursor response to illness in hospitalized foals

Sepsis is a major cause of morbidity and mortality in neonatal foals. Relative adrenal insufficiency (RAI), defined as an inadequate cortisol response to stress, has been associated with sepsis, prematurity, and poor outcome in newborn foals. In addition to cortisol, the adrenal gland synthesizes several biologically important steroids and steroid precursors, including aldosterone, androgens, and progestogens. However, concentration of these hormones during hospitalization and their association with the severity of disease and mortality in critically ill foals have not been completely evaluated. We hypothesized, that in addition to cortisol and aldosterone, concentration of steroid precursors (progestogens and androgens) will be altered in critically ill foals. We also proposed that septic foals will have higher concentrations of steroid precursors than healthy foals, and steroid concentrations will be persistently increased during hospitalization in non-surviving septic and premature foals. Foals <4 days of age were categorized as healthy, septic, sick non-septic, and premature based on physical exam, medical history, and laboratory data. Blood samples were collected on admission (0 h), 24 h, and 72 h after admission. Concentrations of steroids and ACTH were measured by immunoassays. The area under the curve over 72 h (AUC0-72h) of hospitalization was calculated for each hormone. Serum cortisol, aldosterone, progesterone, pregnenolone, dehydroepiandrosterone sulfate (DHEAS), and 17 α-hydroxyprogesterone concentrations were higher in septic and premature foals compared to healthy foals at 0 h and throughout 72 h of hospitalization (P < 0.05). Plasma ACTH concentrations were higher in septic and premature foals on admission compared to healthy controls (P < 0.05). The progesterone (AUC0-72h) cut-off value above which non-survival could be reliably predicted in hospitalized foals was 1,085 ng/mL/h, with 82% sensitivity and 77% specificity. Critically ill neonatal foals had an appropriate response to stress characterized by increased concentrations of cortisol and steroid precursors on admission. A rapid decline in steroid concentration was observed in healthy foals. However, persistently elevated progestogen and androgen concentrations were associated with a lack of improvement in the course of disease and poor outcome.

Echocardiographic Features of the Ductus Arteriosus and the Foramen Ovale in a Hospital-Based Population of Neonatal Foals.

Simple SummaryIn fetal circulation, the distribution of oxygenated blood from the maternal placenta is facilitated by two intracardiac shunts. Oxygenated blood flows from the right atrium to the left heart through the foramen ovale, which is formed by the septum primum and septum secundum. Less oxygenated blood is directed to the placenta through the ductus arteriosus, which connects the pulmonary artery and the aorta. The ductus arteriosus and foramen ovale should close after birth. However, knowledge about the exact time of closure of those structures in foals is limited. The current study investigates the ultrasonographical closure of both the ductus arteriosus and the foramen ovale in healthy and diseased neonatal foals. Cardiac auscultation and ultrasound were performed on fifty foals. Cardiac murmurs were common, and in some foals, the ductus arteriosus was still open at ten days of age. The foramen ovale was not open; however, a fluttering motion of the septum primum into the left atrium was a common finding in healthy and diseased foals. The exact clinical importance of those findings needs to be further elucidated.The ductus arteriosus (DA) and foramen ovale (FO), including the septum primum (SP) and septum secundum (SS), are important structures in fetal circulation and are unexplored in neonatal equids. The objective of this study is to describe echocardiographic characteristics in a hospital-based population of neonatal foals. On days 2, 5 and 10 after parturition, cardiac ultrasound was performed, and clinical data were collected in healthy and diseased Warmblood foals. Fifty healthy (n = 15) and diseased (n = 35) Warmblood foals were examined. A left-sided and right-sided holosystolic murmur was audible in 98% (n = 42) and 51% (n = 22), respectively, on day 2; in 81% (n = 25) and 19% (n = 6) on day 5; and in 44% (n = 4) and 11% (n = 1) on day 10. The median grade of the systolic murmurs was higher when the DA was open. Flow through the DA could be visualized with color flow and continuous wave (CW) Doppler from the left parasternal long-axis view of the pulmonary artery in 40/43 foals on day 2, 9/31 foals on day 5 and 2/9 foals on day 10. The DA diameter was 2 ± 1 mm on day 2, 2 ± 1 mm on day 5 and 1 mm on day 10. The thickness of both septa of the FO was similar. The SP fluttered into the left atrium at all ages, but the maximal distance between the SP and SS decreased over time. In conclusion, cardiac murmurs, a patent DA and fluttering FO are frequent findings in neonatal foals. While these findings are probably physiological, the clinical importance needs to be further elucidated.

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

Simple SummaryBased on human medicine, Neonatal Encephalopathy is the term used by equine clinicians for newborn foals which develop a variety of non-infectious neurological signs in the immediate postpartum period. It has become the preferred term because it does not imply a specific underlying etiology or pathophysiology, as hypoxia and ischemia may not be recognized in all cases. Understanding the underlying pathophysiology is important in formulating a rational approach to diagnosis. Our aim is to clinically characterize a population of foals spontaneously affected by Neonatal Encephalopathy and to evaluate the levels of trophic factors, such as nerve growth factor and vascular epithelial growth factor, and thyroid hormones obtained at birth/admission from a population of affected foals and in the first 72 h of life/hospitalization, as well as the expression of trophic factors in the placenta of mares that delivered foals affected by Neonatal Encephalopathy. The less pronounced decrease of the two trophic factors compared to healthy foals, their close relationship with thyroid hormones over time, and the dysregulation of trophic factor expression in placental tissues, could be key regulators in the mechanisms of equine 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.

Simple SummaryThe end of pregnancy, the birth and the sudden need for the fetus to adapt to the extra-uterine environment make the perinatal period eventful in all species. Trophic factors, such as nerve growth factor and vascular endothelial growth factor, as well as thyroid hormones, take part in the processes associated with the final maturation of the fetus. Our aim is to evaluate the levels of trophic factors and thyroid hormones obtained at parturition from a population of healthy mares and foals and in the first 72 h of foal life, as well as the expression of trophic factors in fetal membranes. The levels of both trophic factors decreased over time in foal plasma and a positive correlation was found between their levels at each time point, but no correlation was found with the thyroid hormone levels. Vascular endothelial growth factor was expressed in all fetal membranes, while nerve growth factor 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.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.

Comparative analysis of haematological, biochemical and nutritional parameters of Dezhou donkey with healthy and weak foals (Equus asinus)

The study was conducted to compare the haematological, biochemical and nutritional parameters between healthy foals (HF) and weak foals (WF, malformation, lameness and drooping ears), and between the corresponding female donkeys to provide a reference for the assessment of healthy status. A total of 34 donkeys with HF (DHF) and 34 with WF (DWF) were selected. Compared to HF, WF had higher leukocyte, neutrophil, platelets (PLT) and the percentage of neutrophil, and their corresponding female donkeys showed the similar tendency; WF had lower birth weight and body measurements. The concentrations of serum urea, total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (TC), low-density lipoprotein cholesterol, β-hydroxybutyric acid (BHBA) and non-esterified fatty acid (NEFA) were increased in WF compared with HF, whereas serum glucose (GLU) was decreased. The concentrations of serum urea, total protein, AST, alkaline phosphatase (ALP), BHBA, NEFA, calcium and phosphorus were increased in DWF compared with DHF, whereas serum albumin (ALB), GLU, kalium, chromium, iron, manganese, lead and zinc were decreased. The hair concentrations of minerals had the same tendency as well, but calcium concentration of hair was opposite. There were significant correlations of kalium, copper, iron and zinc contents between serum and hair. In plasma, the contents of threonine, glutamic acid, alanine, arginine in DWF were greater than DHF, whereas valine content was lower. In conclusion, there were significant differences in some haematological, biochemical and nutritional parameters, which suggested that the malnutrition of the corresponding female donkeys was probably responsible for malformation, lameness and drooping ears of foals. Highlights Weak foals (WF) had higher leukocyte and neutrophil count, platelets (PLT) and the percentage of neutrophil than healthy foals (HF), and their corresponding female donkeys showed the similar tendency. WF had higher concentrations than HF in serum urea, total protein, aspartate aminotransferase (AST), alkaline phosphatase (ALP), β-hydroxybutyric acid (BHBA), non-esterified fatty acid (NEFA), but had lower concentration in serum glucose (GLU), and their corresponding female donkeys showed the similar tendency. Donkeys with WF had higher concentrations of threonine, glutamic acid, alanine, arginine in plasma than donkeys with HF, but lower concentrations of valine in plasma and some mineral elements in serum and hair.

A prospective study of serum amyloid A in relation to plasma administration in neonatal foals

SAA is a commonly used biomarker for measuring acute inflammation in equine practice, and the administration of prophylactic plasma to foals is a routine practice in large breeding farms. Despite this, limited information is available on the values of SAA in healthy or sick neonatal foals following this common procedure. A prospective study was conducted with 31 foals from a veterinary hospital in Texas in one year. Enrolled foals were part of a foaling program, where a prophylactic hyperimmunized plasma was administered 12 h after birth. Blood was collected for SAA measurements at birth and at 12 h (pre-plasma), 13 h (post-plasma), 24 h, 48 h, 72 h, and 96 h. Eight of the foals were clinically ill prior to plasma administration, and 23 foals were clinically normal. The mean SAA of all foals at birth was 1 μg/mL, increased to 11 μg/mL at 12 h (pre-plasma), and at 13 h (post-plasma) was 155 μg/mL. At 13 h, 65% of normal foals and 63% of sick foals had an SAA value >100 μg/mL. Transient but substantial increases in SAA following prophylactic plasma administration were frequently observed in this study. Veterinarians evaluating neonatal foals for clinical disease in the field should be cognizant of the timing of blood sampling in relation to plasma administration.