Peripheral blood markers of sepsis in foals born from mares with experimentally induced ascending placentitis

Foals born alive from mares with ultrasonographically assessed placental abnormalities: Neonatal health and development up to weaning compared to foals from healthy mares

Little is known about the health status of foals born alive from mares treated for placental disease. The aims of the present study were (1) to compare the neonatal health status and health development during the rearing period of foals born from mares treated for ultrasonographically assessed placental abnormalities (UPA) to age-matched healthy foals from the same warmblood stud and (2) analyze the influence of mare's placental health on colostrum quality. Foals (n = 127) born from mares with UPA (UPA group; P) in 2017-2019 were compared to 127 foals born from healthy mares (control group; C). Sixty-six UPA mares showed subclinical placental abnormalities (PSc1) and 61 mares showed clinical placental abnormalities (PSc2). The colostrum quality assessed by refractometry showed that healthy mares had 42 excellent (>30 %), 73 good (20-30 %) and 6 poor (<20 %) colostrum, whereas UPA mares showed 29 excellent, 66 good and 26 poor colostrum quality (P < 0.001). The administration of high-quality colostrum was more frequent in the UPA group (17.5 %) than in C (7.9 %; P = 0.024). The mean (±SD) gestation length of UPA mares was shorter (330 ± 11 days) and foal birth weight lower (54.2 ± 7.3 kg) compared to the healthy pregnancies (335 ± 11 days; P = 0.002 and 57.0 ± 6.6 kg; P < 0.001). The number of foals with a reduced immunoglobin G concentration 14 h postpartum was significantly higher in PSc2 (P = 0.007). Foals born from UPA mares received foreign plasma (P 25.4 % vs C 4.2 %; P = 0.028) more frequently. Premature placental separation, the occurrence of the retention of fetal membranes, placental weight, foal vitality and the white blood cell count did not differ between groups. Regarding the health status of the foal in the neonatal period (1-14 days postpartum), 10 foals (8.1 %) born from UPA pregnancies showed maladjustment syndrome, whereas none of the foals in the control group showed this condition (P < 0.001). Foals from UPA mares developed diarrhea more often (P 31.4 % vs C 19.9 %; P = 0.042), whereas omphalitis, pneumonia, sepsis, meconium obstipation and contracted tendons did not differ between the groups. Multimorbidity and treatment were more frequent in foals born from UPA pregnancies (P 12.8 % vs C 4.7 %; P = 0.004 and 59.6 % vs 40.4 %; P = 0.007). In conclusion, foals born alive from UPA mares face decreased immunity and an increased risk of disease during the first 14 days postpartum. The study underlines that colostrum supplementation from a healthy mare seems essential in UPA pregnancies.

The Systemic Inflammatory Response Syndrome and Predictors of Infection and Mortality in 1068 Critically Ill Newborn Foals

BACKGROUND

Sepsis has been defined in humans as the concurrent proven or suspected presence of microbial infection and the systemic inflammatory response syndrome (SIRS). Sepsis is the leading cause of morbidity and mortality in neonatal foals. The clinical utility of using SIRS or its individual components to predict infection and mortality in critically ill foals is currently unknown.

OBJECTIVES

Assess the ability of history and signalment, clinical findings, laboratory results, and SIRS-related indices to predict infection and mortality in critically ill foals.

ANIMALS

Retrospective, multi-center, cross-sectional study using a convenience sample of 1068 critically ill foals < 3 days of age admitted to 16 veterinary referral hospitals in 4 countries.

METHODS

Data were retrieved from medical records. Infection was defined as the presence of bacteremia (positive blood culture) or clinical identification of an infected focus on admission. Univariate non-parametric and categorical methods, multivariate logistic regression, and classification tree methods were used for statistical analysis.

RESULTS

Foal age at admission and presence of toxic neutrophils were independent predictors of infection, whereas SIRS-related indices were not predictive of infection. In-hospital mortality was 24%. Independent predictors for mortality were hypokinetic pulses, cold extremities, presence of seizures, blood L-lactate concentration > 6.0 mmol/L, and increased serum potassium and total bilirubin concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

The presence of infection in critically ill newborn foals was not predicted by SIRS indices. Cardiovascular dysfunction was strongly associated with mortality, suggesting that maintaining adequate perfusion and pulse pressure should be important treatment goals.

Increased plasma nucleosomes are associated with severe sepsis in foals

Sepsis is a main cause of death in neonatal foals. While the syndrome is not completely understood, sepsis is a dysregulated inflammatory response of the host to infection. It can be difficult to diagnose because of varying and non-specific clinical signs and imperfect diagnostic tests. Increased circulating nucleosome levels have been detected in humans and animals with sepsis, but this has not been documented in foals. Nucleosomes are released extracellularly during neutrophil extracellular trap formation, as well as from damaged and dead cells. We analysed plasma samples from clinically healthy (n = 16), sick non-septic (n = 31) and septic (n = 36) foals using an enzyme-linked immunosorbent assay (ELISA) that targeted nucleosomes. Septic foals with evidence of hypoperfusion and/or organ dysfunction were classified as severe sepsis (n = 24). The main objective was to determine if nucleosome levels were increased in foals with sepsis, particularly those with severe sepsis. Our data identified that nucleosome levels in foals with severe sepsis on the day of study entry were increased significantly compared to all other foals. There was not a significant difference in nucleosome levels between sick non-septic or clinically healthy foals. Foal groups were not age-matched and factors associated with the clinical nature of the study may have affected the results. Further research with larger numbers of foals of similar ages, would be necessary to determine if the analysis of nucleosomes and related biomarkers are helpful adjuncts for the assessment and understanding of equine neonatal sepsis.

Plasma alpha-fetoprotein in neonatal foals affected by prematurity, sepsis and neonatal encephalopathy

Alpha-fetoprotein (AFP) concentrations have been reported in healthy foals and proposed as a biomarker of sepsis in foals born from mares with experimentally induced placentitis. This study aimed to describe the diagnostic and prognostic value of plasma AFP in foals spontaneously affected by different diseases. The study included all foals less than 72 h old that were diagnosed with either: (1) prematurity (PRE), when born prior to 320 days of gestation with immature physical characteristics; (2) sepsis (SEP), in the presence of both positive blood culture and SIRS or (3) neonatal encephalopathy (NE), with evidence of hypoxic-ischemic injury. Data from healthy foals (H; n=20) were obtained from a previous study. Foals received a complete physical and hematochemical evaluation and blood culture sample collection at hospital admission. Forty-six foals with an average age of 16 h were enrolled and divided into: PRE group (n=7); SEP group (n=14); NE group (n=25). AFP was measured in plasma collected at admission using a commercially available immunoassay validated for horses. AFP was increased in foals in PRE, SEP and NE groups compared with healthy ones (P<0.001) but was not able to discriminate between different diseases and outcomes. Overall, AFP was negatively correlated with foal age (r=-0.6; P<0.001), foal weight (r=-0.3; P=0.048), monocytes count (r=-0.4; P=0.011) and SAA concentration (r=-0.4; P=0.011). AFP appears to be a useful but non-specific indicator of neonatal health, since it upregulates not only in the presence of SIRS and bacteremia, but also during prematurity and hypoxic-ischemic injury.

Equine Placentitis in Mares Induces the Secretion of Pro-Inflammatory Cytokine eIL-1β and the Active Extracellular Matrix Metalloproteinase (MMP)-9

Equine placentitis is characterized by infection and inflammation of the placenta. Different biomarkers associated with this inflammatory response have been evaluated in experimentally induced equine placentitis, but not in pregnant mares with spontaneous placentitis. The aim of the current study was to determine the concentration of eIL-1β and the activity of proMMP-2 and proMMP-9 in the serum of healthy mares and mares with placentitis on days 240 and 320 of gestation to explore whether these biomarkers are associated with equine maternal placentitis and/or with the birth of an infected or inviable foals. Serum samples were collected from sixteen pregnant English Thoroughbred mares, retrospectively classified as follows: (1) healthy mares with full-term gestation; and (2) mares with ultrasonographic signs of placentitis. The health of each foal was examined at birth, and it was decided to classify the cases into four groups: (1) healthy mares delivering a healthy foals (HM-HF, n = 6); (2) mares with USP delivering a healthy foal (USP-HF, n = 3); (3) mares with USP delivering a live septic foal (USP-LSeF, n = 4); and (4) mares with USP delivering a dead foal (USP-DF, n = 3). eIL-1β was quantified by ELISA, and proMMP-2 and proMMP-9 activity by gelatin zymography electrophoresis. In healthy mares, the serum concentrations of eIL-1β underwent a significant 16.5-fold increase from day 240 to day 320 of gestation. Although similar results were found in the mares with ultrasonographic signs of placentitis that delivered a healthy foal, those delivering a live septic or nonviable foal exhibited much higher concentrations of eIL-1β. proMMP-2 and proMMP-9 activity was not associated with maternal placentitis, foal infection, or death. Hence, the presence of placentitis severe enough to affect the health of the foal can be confirmed or discarded by determining the eIL-1β concentration in mares that have shown ultrasonographic signs of placentitis.

Use of serum amyloid A in equine medicine and surgery

Serum amyloid A (SAA) has become an indispensable part of the management of equine patients in general practice and specialized hospital settings. Although several proteins possess acute phase properties in horses, the usefulness of SAA exceeds that of other acute phase proteins. This is due to the highly desirable kinetics of the equine SAA response. SAA concentrations exhibit a rapid and pronounced increase in response to inflammation and a rapid decline after the resolution of inflammation. This facilitates the detection of inflammatory disease and real-time monitoring of inflammatory activity. SAA may be used in all stages of patient management: (1) before diagnosis (to rule in/rule out inflammatory disease), (2) at the time of diagnosis (to assess the severity of inflammation and assist in prognostication), and (3) after diagnosis (to monitor changes in inflammatory activity in response to therapy, with relapse of disease, or with infectious/inflammatory complications). By assessing other acute phase reactants in addition to SAA, clinicians can succinctly stage inflammation. White blood cell counts and serum iron concentration change within hours of an inflammatory insult, SAA within a day, and fibrinogen within 2-3 days; the interrelationship of these markers thus indicates the duration and activity of the inflammatory condition. Much research on the equine SAA response and clinical use has been conducted in the last decade. This is the prerequisite for the evidence-based use of this analyte. However, still today, most published studies involve a fairly low number of horses. To obtain solid evidence for use of SAA, future studies should be designed with larger sample sizes.

The fecal bacterial microbiota of healthy and sick newborn foals

BACKGROUND

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.

OBJECTIVE

To describe and compare the fecal bacterial microbiota in healthy and sick foals using next-generation sequencing techniques.

ANIMALS

Hospitalized (17) and healthy foals (21).

METHODS

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.

RESULTS

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.

CONCLUSION AND CLINICAL IMPORTANCE

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.

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.

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.

Effects of intravenous administration of peripheral blood-derived mesenchymal stromal cells after infusion of lipopolysaccharide in horses

BACKGROUND

A systemic and dysregulated immune response to infection contributes to morbidity and mortality associated with sepsis. Peripheral blood-derived mesenchymal stromal cells (PB-MSC) mitigate inflammation in animal models of sepsis. Allogeneic PB-MSC administered IV to horses is well-tolerated but therapeutic benefits are unknown.

HYPOTHESIS

After IV lipopolysaccharide (LPS) infusion, horses treated with PB-MSC would have less severe clinical signs, clinicopathological abnormalities, inflammatory cytokine gene expression, and oxidative stress compared to controls administered a placebo.

ANIMALS

Sixteen horses were included in this study.

METHODS

A randomized placebo-controlled experimental trial was performed. Sixteen healthy horses were assigned to 1 of 2 treatment groups (1 × 10⁹  PB-MSC or saline placebo). Treatments were administered 30 minutes after completion of LPS infusion of approximately 30 ng/kg. Clinical signs, clinicopathological variables, inflammatory cytokine gene expression, and oxidative stress markers were assessed at various time points over a 24-hour period.

RESULTS

A predictable response to IV LPS infusion was observed in all horses. At the dose administered, there was no significant effect of PB-MSC on clinical signs, clinicopathological variables, or inflammatory cytokine gene expression at any time point. Antioxidant potential was not different between treatment groups, but intracellular ROS increased over time in the placebo group. Other variables that changed over time were likely due to effects of IV LPS infusion.

CONCLUSIONS AND CLINICAL IMPORTANCE

Administration of allogeneic PB-MSC did not cause clinically detectable adverse effects in healthy horses. The dose of PB-MSC used here is unlikely to exert a beneficial effect in endotoxemic horses.