Jamie Jennifer Kopper

Background: Oxidative injury occurs in septic people, but the role of oxidative stress and antioxidants has rarely been evaluated in foals. Objectives/Hypothesis: To measure reactive oxygen species (ROS), biomarkers of oxidative injury, and antioxidants in neonatal foals. We hypothesized that ill foals would have higher blood concentrations of ROS and biomarkers of oxidative injury and lower concentrations of antioxidants compared to healthy foals. Animals: Seventy-two hospitalized and 21 healthy neonatal foals. Methods: Prospective cohort study. Reactive oxygen species (hydrogen peroxide [H2O2]), biomarkers of oxidative injury (malondialdehyde [MDA], protein carbonyl), and antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione, and glutathione reductase [GR] and peroxidase [GPx]) were measured from foals at admission. Measured variables were compared between healthy and ill foals using a 1-way ANOVA by Tukey's multiple comparisons test. Results: Ill foals (n = 51) had significantly higher mean concentrations of H2O2 (healthy 2.6 ± 1.4 nmol/mL, ill 6.8 ± 4.6 L nmol/mL; 95% CI), MDA (healthy 31.2 ± 14.4 nmol/mL, ill 114.3 ± 94.0 nmol/mL; 95% CI), and protein carbonyl (healthy 0.07 ± 0.01 nmol/mg protein, ill 0.12 ± 0.02 nmol/mg protein, 95% CI). Significant lower CAT (healthy 0.4 ± 0.3 mU/mg protein, ill 0.02 ± 0.02 mU/mg protein, 95% CI), glutathione (healthy 238.5 ± 101.9 μg/mL, ill 110.7 ± 37.8 μg/mL, 95% CI; P < .0001), GR (healthy 1.6 ± 1.8 mU/mg protein, ill 0.4 ± 0.5 mU/mg protein, 95% CI), and GPx (healthy 0.01 ± 0.003 mU/mg protein, ill 0.007 ± 0.002 mU/mg protein, 95% CI) were also noted. Conclusions and Clinical Importance: Oxidative stress and lower antioxidant concentrations occur in ill and bacteremic neonatal foals. These variables should be considered during the treatment of ill foals.

Gastrointestinal disease is a leading cause of death in mature horses. A lack of in vitro modeling has impeded the development of novel therapeutics. The objectives of this study were to develop and further characterize a small intestinal monolayer cell culture derived from equine jejunum including establishing normal measurements of intestinal permeability and restitution. Three-dimensional enteroids, derived from postmortem sampling of equine jejunum, were utilized to develop confluent epithelial monolayers. The presence of differentiated intestinal epithelial cell types and tight junctions were confirmed using histology, reverse transcription PCR (RT-PCR), RNAscope, protein immunofluorescence and transmission electron microscopy. Transepithelial resistance (TER) and macromolecule flux were assessed as measurements of paracellular and transcellular permeability. Scratch assays were utilized to model and assess intestinal restitution. Monolayer cell cultures reached 100% confluency by ~5–7 days. Equine jejunum monolayers were confirmed as epithelial in origin, with identification of differentiated intestinal epithelial cell types and evidence of tight junction proteins. Function of the intestinal barrier was supported by acquisition of physiologically normal TER values (179.9 ± 33.7 ohms*cm²) and limited macromolecule flux (22 ± 8.8% at 60 min). Additionally, following a scratch wound, epithelial cell monolayers migrated to close gap defects within 24 h. In conclusion, this study describes the development of a novel intestinal epithelial monolayer cell culture for equine jejunum, and provides evidence of intestinal epithelial cell differentiation, formation of physiologically relevant barrier function and use as a model of intestinal restitution to test potential therapeutics for equine colic.

Preclinical biomedical research is limited by the predictiveness of in vivo and in vitro models. While in vivo models offer the most complex system for experimentation, they are also limited by ethical, financial, and experimental constraints. In vitro models are simplified models that do not offer the same complexity as living animals but do offer financial affordability and more experimental freedom; therefore, they are commonly used. Traditional 2D cell lines cannot fully simulate the complexity of the epithelium of healthy organs and limit scientific progress. The One Health Initiative was established to consolidate human, animal, and environmental health while also tackling complex and multifactorial medical problems. Reverse translational research allows for the sharing of knowledge between clinical research in veterinary and human medicine. Recently, organoid technology has been developed to mimic the original organ’s epithelial microstructure and function more reliably. While human and murine organoids are available, numerous other organoids have been derived from traditional veterinary animals and exotic species in the last decade. With these additional organoid models, species previously excluded from in vitro research are becoming accessible, therefore unlocking potential translational and reverse translational applications of animals with unique adaptations that overcome common problems in veterinary and human medicine.

Background: Clinicopathological findings and their association with the outcome and development of laminitis in horses with acute diarrhoea has not been investigated in a multicentre study across different geographic regions.Objectives: Describe and compare clinicopathologic findings of diarrhoeic horses between different geographic regions, survival rates and factors associated with non‐survival and laminitis.Study design: Multicentre retrospective case series.Methods: Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020 was collected, and clinicopathological data were compared between surviving and non‐surviving horses and horses that did and did not develop laminitis. Survival rates and seasonal and geographic differences were also investigated.Results: One thousand four hundred thirty‐eight horses from 26 participating institutions from 4 continents were included; 76% survived to discharge with no differences identified between geographic regions. The survival proportion of horses with SIRS and creatinine concentrations > 159 μmol/L was 55% (154/279) compared with 81% (358/437) for those with SIRS and creatinine concentrations < 159 μmol/L (p < 0.001). The survival proportion of horses with SIRS that had an L‐lactate concentration > 2.8 mmol/L was 59% (175/298) compared with 81% (240/296) in horses with SIRS and L‐lactate concentration < 2.8 mmol/L (p < 0.001). The proportion of horses that developed laminitis was lower in Europe (4%, 19/479) compared with North America (8%, 52/619), Australia (8%, 12/138) and Latin America (11%, 16/146) (p < 0.05). More horses developed laminitis in the summer (46%, 39/85) compared with winter (18%, 15/85), spring (18%, 15/85) and fall (19%, 16/85) (p < 0.01). Horses with laminitis had greater odds of non‐survival than those without laminitis (OR: 3.73, 95% CI: 2.47–5.65).Main limitations: Not all variables were available for all horses due to the retrospective nature.Conclusions: Clinicopathological findings in horses with acute diarrhoea and their association with survival are similar across geographic regions. However, developing laminitis secondary to diarrhoea is less common in Europe. In addition, factors associated with non‐survival were indicative of disease severity and subsequent cardiovascular compromise.

Background: An international description of the diagnostic approaches used in different institutions to diagnose acute equine diarrhoea and the pathogens detected is lacking.Objectives: To describe the diagnostic approach, aetiological agents, outcome, and development of laminitis for diarrhoeic horses worldwide.Study design: Multicentre retrospective case series.Methods: Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020, including diagnostic approaches, pathogens detected and their associations with outcomes, were compared between institutions or geographic regions.Results: One thousand four hundred and thirty‐eight horses from 26 participating institutions from 4 continents were included. Overall, aetiological testing was limited (44% for Salmonella spp., 42% for Neorickettsia risticii [only North America], 40% for Clostridiodes difficile, and 29% for ECoV); however, 13% (81/633) of horses tested positive for Salmonella, 13% (35/262) for N. risticii, 9% (37/422) for ECoV, and 5% (27/578) for C. difficile. C. difficile positive cases had greater odds of non‐survival than horses negative for C. difficile (OR: 2.69, 95%CI: 1.23–5.91). In addition, horses that were positive for N. risticii had greater odds of developing laminitis than negative horses (OR: 2.76, 95%CI: 1.12–6.81; p = 0.029).Main limitations: Due to the study's retrospective nature, there are missing data.Conclusions: This study highlighted limited diagnostic investigations in cases of acute equine diarrhoea. Detection rates of pathogens are similar to previous reports. Non‐survival and development of laminitis are related to certain detected pathogens.

Summary: Background: Analgesic protocols related to orchiectomy or castration of young horses vary widely depending on geographic location, educational background of the veterinarian, and other demographic factors. Specific practices of equine veterinarians in the United States (US) have not been reported. Objectives: To determine perioperative pain management practices of equine veterinarians in the United States as they relate to castration of healthy yearling colts. Study design: Cross‐sectional survey. Methods: An internet‐based questionnaire included items related to analgesic drugs used in association with castration of healthy yearling colts. Demographic, educational, and experiential factors associated with routine recommendation of analgesic medications after castration were analysed with calculation of odds ratios (OR) with 95% confidence intervals (CI) and multivariable logistic regression. Results: Responses from 146 equine veterinarians in the United States revealed that 112/146 (76.7%) administered a nonsteroidal anti‐inflammatory drug (NSAID) at the time of castration, and 107/143 respondents (73.3%) recommended administration of NSAIDs for a median of 3 days (IQR = 3–5) after surgery. Veterinarians who recommended NSAID analgesia after castration provided a higher pain severity score for horses at 24 h after a routine castration. Routine recommendation of post‐castration NSAID analgesia was associated with veterinarians who were employed in a multi‐veterinarian practice (OR = 2.7, 95% CI = 1.2–6.1) and completed their veterinary education in the year 2000 or more recently (OR = 2.6, 95% CI = 1.1–5.9). Main limitations: Possible distribution, self‐selection, and response biases as a result of convenience sampling methodology and possible recall bias of respondents. Conclusions: Perioperative pain management practices vary widely among US veterinarians but the majority of veterinarians, especially more recent graduates and those in multi‐veterinarian practices, recommend administration of an NSAID at the time of castration and for a median of 3 days after surgery.

Background: Analgesic protocols related to orchiectomy or castration of young horses vary widely depending on geographic location, educational background of the veterinarian, and other demographic factors. Specific practices of equine veterinarians in the United States (US) have not been reported. Objectives: To determine perioperative pain management practices of equine veterinarians in the US as they relate to castration of young male horses. Study Design: Cross-sectional survey Methods: An internet-based questionnaire included items related to analgesic drugs used in association with castration of healthy yearling colts. Demographic and educational factors associated with routine recommendation of analgesic medications after castration were analyzed using logistic regression. Results: Responses from 146 equine veterinarians in the US revealed that 112/146 (76.7%) administered a nonsteroidal anti-inflammatory drug (NSAID) at the time of castration. Routine recommendation of post-castration analgesia was associated with veterinarians who were employed in a multi-veterinarian practice, completed their veterinary education after 2000, and provided a higher pain severity score for horses at 24 hours after a routine castration. Main Limitations: Possible distribution, self-selection, response, and recall biases as a result of convenience sampling methodology. Conclusions: Perioperative pain management practices vary widely among US veterinarians but the majority of veterinarians, especially more recent graduates, recommend administration of an NSAID.