Neurologic Disorders of Neonatal Foals

Plasma UCHL-1 as a Biomarker of Brain Injury in Hospitalized Foals With Neonatal Encephalopathy

A plasma biomarker such as ubiquitin carboxyl-terminal hydrolase L1 (UCHL-1) to distinguish neonatal encephalopathy (NE) from other disorders and provide prognostic information would be useful for equine practitioners. In this prospective study, plasma UCHL-1 was measured in 331 hospitalized foals ≤4 days of age. Clinical diagnoses of neonatal encephalopathy only (NE group, n = 77), sepsis only (Sepsis group, n = 34), concurrent sepsis and NE (NE+Sepsis group, n = 85), or neither sepsis nor NE (Other group, n = 101) were made by the attending veterinarian. Plasma UCHL-1 concentrations were measured by ELISA. Differences between clinical diagnoses groups were evaluated and receiver operator curve (ROC) analysis was performed to assess diagnostic and prognostic performance. Median admission UCHL-1 concentration was significantly higher for NE (18.22 ng/mL; 7.93-37.43) and NE+Sepsis (17.42 ng/mL; 7.67-36.24) groups than Other foals (7.77 ng/mL; 3.92-22.76). Admission UCHL-1 was significantly higher in nonsurvivors (16.66 ng/mL; 6.89-34.84) than survivors (10.27 ng/mL; 5.82-29.94). Overall diagnostic performance of admission UCHL-1 concentration for NE diagnosis was determined (AUC 0.61; 95% confidence interval [CI] = 0.55-0.68); sensitivity and specificity for predicting NE were 73% and 49% respectively. Overall prognostic performance of time to lowest UCHL-1 concentration for predicting nonsurvival was determined (AUC 0.72; 95% CI = 0.65-0.79); sensitivity and specificity were 86% and 43% respectively. In this foal population, differences in plasma UCHL-1 concentrations were observed between foals with NE or NE with sepsis, and other diagnoses. The diagnostic and prognostic value of admission UCHL-1 concentration was limited.

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.

Modelling Neurological Diseases in Large Animals: Criteria for Model Selection and Clinical Assessment

Issue: The impact of neurological disorders is recognised globally, with one in six people affected in their lifetime and few treatments to slow or halt disease progression. This is due in part to the increasing ageing population, and is confounded by the high failure rate of translation from rodent-derived therapeutics to clinically effective human neurological interventions. Improved translation is demonstrated using higher order mammals with more complex/comparable neuroanatomy. These animals effectually span this translational disparity and increase confidence in factors including routes of administration/dosing and ability to scale, such that potential therapeutics will have successful outcomes when moving to patients. Coupled with advancements in genetic engineering to produce genetically tailored models, livestock are increasingly being used to bridge this translational gap. Approach: In order to aid in standardising characterisation of such models, we provide comprehensive neurological assessment protocols designed to inform on neuroanatomical dysfunction and/or lesion(s) for large animal species. We also describe the applicability of these exams in different large animals to help provide a better understanding of the practicalities of cross species neurological disease modelling. Recommendation: We would encourage the use of these assessments as a reference framework to help standardise neurological clinical scoring of large animal models.

Complex central nervous system malformations in a Dutch Warmblood foal

A neonatal Dutch Warmblood colt was evaluated for inability to stand, incoordination and intention tremor. Despite partial improvement in clinical signs during the first 4 days of hospitalization, neurological deficits remained. Magnetic resonance imaging identified a unilateral infratentorial arachnoid cyst‐like lesion with ipsilateral compression and displacement of the cerebellar hemisphere, absent corpus collosum, polymicrogyria, suspect leukoencephalopathy, and noncompressive occipitoatlantal malformation. Improvement in clinical signs during the first 6 months of life suggests that horses can survive with complex congenital neurological malformations, but prognosis for athletic performance is poor. The accessibility of magnetic resonance imaging should improve the diagnostic accuracy of central nervous system disorders in neonatal foals in which congenital malformations are suspected. Euthanasia often is elected in foals with suspected congenital central nervous system disorders because of poor prognosis for athletic performance, limiting understanding of clinical progression in these cases.

Relation between Apgar scoring and physical parameters in 44 newborn Amiata donkey foals at birth

The assessment of the behavior and physiological parameters of neonatal foals is essential in the detection of early signs of illness. Modified Apgar scoring systems from human medicine exist and have been validated in foals as a guide for assessing neonatal viability after birth. This study evaluated the viability of 44 Amiata donkey foals at birth, by assessing the Apgar score and comparing the relationship between viability and various physical parameters. A total of 44 Amiata donkey foals and 27 jennies were enrolled in this study. An expert operator examined each foal within 5 min of birth. A complete physical examination was performed, along with an existing four-parameter Apgar score. The presence of the suckling reflex was evaluated. The interval time needed to acquire sternal recumbency and quadrupedal position, as well as nurse from the mare, were recorded. In addition, heart rate (HR), respiratory rate (RR), and rectal body temperature (BT) were measured. Results were expressed as median ± standard error, minimum and maximum values. The effects of the Apgar score on time to reach sternal position and quadrupedal standing, time to nurse from the mare, RR, HR, and BT were estimated along with the differences related to Apgar scoring and gender. Differences between female and male donkey foals regarding the time to acquire sternal position and quadrupedal standing, time to nurse from the mare, RR, HR, and BT were also assessed. Differences between female and male donkey foals regarding the Apgar score was evaluated using a chi-Square test. Finally, the reference values for Amiata donkeys were also calculated. Twenty/44 (45.4%) foals were colts and 24/44 (54.5%) were fillies born from 27 jennies. None of the foals showed an Apgar score lower than 6. Twenty-nine out of 44 foals showed an Apgar score of 8/8, 10/44 a score of 7/8, while 5 foals (11.3%) showed a score of 6/8. No differences between fillies and colts in relation to the Apgar score were obtained.

Equine Neonatal Encephalopathy: Facts, Evidence, and Opinions

Neonatal encephalopathy (NE) and neonatal maladjustment syndrome (NMS) are terms used for newborn foals that develop noninfectious neurologic signs in the immediate postpartum period. Cerebral ischemia, hypoxia, and inflammation leading to neuronal and glial dysfunction and excitotoxicity are considered key mechanisms behind NE/NMS. Attention has been placed on endocrine and paracrine factors that alter brain cell function. Abnormal steroid concentrations (progestogens, neurosteroids) have been measured in critically ill and NE foals. In addition to supportive treatment, antimicrobials should be considered. Controversies regarding the pathophysiology, diagnosis, and treatment of NE and NMS will remain until controlled mechanistic and therapeutic studies are conducted.

Neonatal Encephalopathy in Calves Presented to a University Hospital

BACKGROUND

While studies have examined bovine dystocia in relation to calf survival, little has been published regarding perinatal morbidity and treatment of newborn calves beyond failure of transfer of passive immunity (FTPI). Neonatal encephalopathy (NE) is a clinical syndrome commonly diagnosed in infants and foals but is poorly described in calves.

HYPOTHESIS/OBJECTIVES

To identify risk factors for development of NE in calves and factors predictive of survival.

ANIMALS

Neonatal calves presented to a University hospital over a 10-year period.

METHODS

Retrospective cohort study (2005-2015). Medical records of all neonatal calves presented to the hospital were examined, and cases of NE were identified. Data pertaining to demographics, dam parity, labor, treatment, and outcome were collected and analyzed with univariate and multivariate statistics.

RESULTS

Of 200 calves in the final analysis, 58 (29%; 95% CI: 22.8-35.8%) were classified as NE and 142 calves as non-NE. In univariate analysis, factors significantly associated with diagnosis of NE included male sex, presence of dystocia, abnormal position in the birth canal, and prolonged labor. In the multivariate model, only orientation of the calf in the birth canal remained significant (OR 2.14; 95% CI: 1.02-4.49; P = 0.044). Overall survival of calves with NE was good (45/58; 77.6%; 95% CI: 64.7-87.5); dam parity and being a twin was significantly associated with nonsurvival.

CONCLUSIONS

Calves born after dystocia, especially if malpresented, should be closely monitored for nursing behavior within the first 24 hours of life. Prognosis for survival is good, but supportive care might be required for several days.

Brainstem auditory evoked responses in foals: reference values, effect of age, rate of acoustic stimulation, and neurologic deficits

Background

Age and rate of acoustic stimulation affect peak latencies in brainstem auditory evoked responses (BAER) in humans. Those effects are unknown in foals.

Hypothesis/Objectives

Our goals were to (1) establish reference values for BAER in foals by using 3 different stimulation protocols, (2) evaluate the effects of age and stimulation frequencies on BAER tracing in foals up to 6 months old, and (3) compare the data with BAER obtained from foals with central nervous system (CNS) disorders.

Animals

Thirty‐nine neurologically normal foals and 16 foals with neurologic diseases.

Methods

Prospective observational clinical study. BAER recorded by using 3 protocols of stimulation (11.33 repetitions per second [Hz]/70 decibel normal hearing level [dBNHL]; 11.33 Hz/90 dBNHL; 90 Hz/70 dBNHL).

Results

No effect of age was observed in normal foals (P > .005). No significant difference was observed for latencies and interpeak latencies (IPL) when comparing foals with neurologic diseases and normal foals (P > .05), but 78.6% of foals with neurologic diseases had an asymmetry in their tracing, reflecting a difference in conduction time between the left and right side of the brainstem. Increasing the stimulation rate did not improve detection of CNS disorders.

Conclusions and Clinical Importance

We propose BAER reference values for foals up to 6 months of age by using 3 protocols. Most foals with neurologic deficits had abnormal BAER tracing.