Microbial populations vary between the upper and lower respiratory tract, but not within biogeographic regions of the lung of healthy horses.

Understanding normal microbial populations within areas of the respiratory tract is essential, as variable regional conditions create different niches for microbial flora, and proliferation of commensal microbes likely contributes to clinical respiratory disease. The objective was to describe microbial population variability between respiratory tract locations in healthy horses. Samples were collected from four healthy adult horses by nasopharyngeal lavage (NPL), transtracheal aspirate (TTA), and bronchoalveolar lavage (BAL) of six distinct regions within the lung. Full-length 16S ribosomal DNA sequencing and microbial profiling analysis was performed. There was a large amount of diversity, with over 1797 ASVs identified, reduced to 94 taxa after tip agglomeration and prevalence filtering. Number of taxa and diversity were highly variable across horses, sample types, and BAL locations. Firmicutes, proteobacteria, and actinobacteria were the predominant phyla. There was a significant difference in richness (Chao1, p = 0.02) and phylogenetic diversity (FaithPD, p = 0.01) between NPL, TTA, and BAL. Sample type (p = 0.03) and horse (p = 0.005) contributed significantly to Bray-Curtis compositional diversity, while Weighted Unifrac metric was only affected by simplified sample type (NPL and TTA vs BAL, p = 0.04). There was no significant effect of BAL locations within the lung with alpha or beta diversity statistical tests. Overall findings support diverse microbial populations that were variable between upper and lower respiratory tract locations, but with no apparent difference in microbial populations of the six biogeographic regions of the lung, suggesting that BAL fluid obtained blindly by standard clinical techniques may be sufficient for future studies in healthy horses.

Noncontact infrared thermometer measurements offer a reasonable alternative to rectal temperature measurement in afebrile horses.

OBJECTIVE: To assess the repeatability of infrared thermometer temperature readings and evaluate the correlation between digital rectal temperature and infrared thermometer temperatures taken at different locations in healthy afebrile horses. ANIMALS: 101 afebrile horses ≥ 1 year old. METHODS: Digital rectal temperatures and infrared temperatures from the eye, gingiva, neck, axilla, and perineum were obtained in a climate-controlled environment and at 2 outdoor ambient temperatures (study period, November 1, 2021, to April 30, 2023). RESULTS: Infrared temperature measurements were well tolerated by horses, including those resistant to rectal temperature. There was significant correlation between rectal temperature and infrared temperature taken at the perineum (R = 0.57; P < .001) and eye (R = 0.37; P < .001). Infrared temperature measurements were highly repeatable, allowing for calculation of reference ranges for the perineum (36.0 to 37.8 °C) and eye (35.7 to 37.1 °C) in climate-controlled conditions. There was increased variance in outside temperatures compared to climate-controlled conditions for the eye (P = .002), gingiva (P = .047), and perineum (P = .005). CLINICAL RELEVANCE: While infrared thermometer temperatures were not numerically the same as rectal temperature using a digital thermometer, measurements at the perineum and eye were correlated with rectal temperature readings. Further, the repeatability of infrared readings allows for computation of reference ranges that make the infrared thermometer a viable alternative for the practicing veterinarian when obtaining a temperature in uncooperative horses. The infrared thermometer was reliable outdoors for the eye, but not the perineum. Additional validation of infrared temperature reference ranges in febrile horses and warmer ambient temperatures is warranted.

Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses.

OBJECTIVE: To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses. DESIGN: Prospective observational study. SETTING: Two university teaching hospitals. ANIMALS: Healthy adult horses (n = 68). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20 minutes, maximum clot firmness, and lysis index at 30 and 45 minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P < 0.001). Differences in CV were found between institutions for CT (P = 0.003) and CFT (P = 0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6-1233.9 seconds; CFT, 89.4-581 seconds; alpha angle, 11.4-53.6°; maximum clot firmness, 18-37.7; lysis index at 30 minutes, 97.3%-102.1%; lysis index at 45 minutes, 80.8%-103.3%; amplitude at 10 minutes, 8.7-28.3; and amplitude at 20 minutes, 17.4-35.7. CONCLUSIONS: VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended.

Prolonged holding time and sampling protocol affects viscoelastic coagulation parameters as measured by the VCM-Vet™ using fresh equine native whole blood.

OBJECTIVES: Determine the effect of sample holding time and single sample reuse on viscoelastic coagulation parameters when using fresh equine native whole blood. ANIMALS: 8 healthy adult horses from a university teaching herd. PROCEDURES: Blood collected by direct jugular venipuncture (18 ga needle, 3 mL syringe) was held at 37 °C for 2, 4, 6, or 8 minutes according to 1 of 2 protocols. Syringes were gently inverted twice, a small amount of blood was expressed, testing cartridges were filled, and placed within the VCM-Vet™ device (Entegrion Inc). Protocol A: samples were processed from a single syringe. Protocol B: 4 syringes were drawn through a single needle. VCM-Vet™ measures assessed included clot time (CT), clot formation time (CFT), alpha angle (AA), amplitude at 10/20 minutes (A10/A20), maximal clot firmness (MCF), and lysis index at 30/45 minutes (LI30/LI45). Differences over time were examined using the Friedman test and post hoc Wilcoxon Rank Sum Test with Bonferroni correction, P ≤ .05. RESULTS: Following Protocol A, there was a significant effect of holding time for CT (P = .02), CFT (P = .04), and AA (P = .05). CT and AA decreased over time, while CFT increased. Samples handled by Protocol B showed no significant difference over time for any of the VCM-Vet™ parameters. CLINICAL RELEVANCE: Sample holding time and handling protocol impact VCM-Vet™ testing results of fresh equine native whole blood. Viscoelastic coagulation samples tested using the VCM-Vet™ may be held unagitated for up to 8 minutes after collection while warm, but should not be reused.

Effect of Firocoxib and Flunixin Meglumine on Large Colon Mural Thickness of Healthy Horses.

Nonsteroidal anti-inflammatory drug (NSAID) administration carries risks of gastrointestinal toxicity. Selective COX-2 inhibitors ("coxibs") were designed to reduce risks of adverse effects but are still associated with gastrointestinal complications in humans. The effect of coxibs on colonic inflammation and integrity in horses is unknown. The study objective was to compare the effects of the coxib firocoxib and the nonselective NSAID flunixin meglumine on ultrasonographic indicators of colonic inflammation in healthy horses. Twelve healthy adult horses were administered flunixin meglumine (1.1 mg/kg IV q12h) and omeprazole (1 mg/kg PO q24h) for 5 days, allowed a 6-month washout period, then administered firocoxib (0.3 mg/kg PO once, then 0.1 mg/kg PO q24h for 4 days) and omeprazole. Transabdominal ultrasonographic examination and serum chemistry profiles were performed at the beginning and end of each treatment week. Colon wall thickness increased over time when horses received firocoxib (median post treatment 5.8 mm, interquartile range 2.8 mm; P < .001), but not flunixin (median 3 mm, interquartile range 1.2 mm; P = .7) and was significantly greater following firocoxib compared to flunixin (P = .003). Subjectively, colonic edema was noted more frequently following treatment with firocoxib (11/12 horses), compared to flunixin (1/12 horses). There were no clinically significant alterations in hematologic parameters after administration of either drug. The increase in colon wall thickness following treatment with the COX-2 selective NSAID firocoxib may suggest a risk of subclinical colitis in healthy horses. Monitoring colonic health when NSAIDs are used in a clinical setting is warranted.

Short-term administration of flunixin meglumine or firocoxib does not alter viscoelastic coagulation profiles in healthy horses.

OBJECTIVE: To evaluate the effect of the cyclooxygenase-2-selective NSAID firocoxib, compared to the nonselective NSAID flunixin meglumine on viscoelastic coagulation parameters in healthy horses. ANIMALS: 12 healthy adult mixed-breed horses. PROCEDURES: Following a crossover protocol, horses were administered flunixin meglumine (1.1 mg/kg, IV, q 12 h for 5 days), allowed a 6-month washout period, and then administered firocoxib (0.3 mg/kg, PO, once, then 0.1 mg/kg, PO, q 24 h for 4 days). Omeprazole (1 mg/kg, PO, q 24 h) was administered concurrently with each NSAID. Viscoelastic coagulation profiles and traditional coagulation parameters (prothrombin time, partial thromboplastin time, and fibrinogen) were measured before and after each treatment. RESULTS: Viscoelastic coagulation parameters were within reference intervals before and after both treatments. There was a statistically significant difference between treatments for amplitude at 10 minutes after clot time (P = .02) and maximum clot formation (P = .02); however, the magnitude of change was not clinically significant. CLINICAL RELEVANCE: Short-term administration of flunixin meglumine and firocoxib did not result in significant alteration of viscoelastic coagulation profiles in healthy horses. However, clinicians should be aware of possible coagulopathy secondary to NSAID administration with long-term use or critical illness, and further study is indicated.

Performance of predictive models of survival in horses undergoing emergency exploratory laparotomy for colic.

OBJECTIVE: To evaluate previously published predictive survival models in a population of horses undergoing colic surgery in the midwestern United States. STUDY DESIGN: Retrospective cohort study; single referral hospital. ANIMALS: A total of 260 horses met the inclusion criteria. METHODS: Medical records of horses undergoing surgical treatment for colic were reviewed. Previously published models were applied to cohort data to predict outcome. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for prediction of short-term survival were calculated. RESULTS: Single-variable and multivariable models performed similarly for prediction of survival, with a mean 79% sensitivity (range: 44%-94%), 48% specificity (range: 22%-83%), 63% PPV (range: 56%-72%), 73% NPV (range: 60%-83%), and 64% accuracy (range: 59%-72%). Blood lactate ≤6 mmol/l and the colic severity score (CSS) were highly sensitive for prediction of survival; however, both had poor specificity. CONCLUSION: Single-variable and multivariable predictive models did not perform as well for prediction of survival in the study cohort compared to original reports, suggesting that population-specific factors contribute to patient survival. CLINICAL SIGNIFICANCE: Predictive models of survival developed in one population may be less reliable when used to predict outcome in horses undergoing colic surgery from an independent population. Additional model testing and refinement using data from multiple surgical centers could be considered to improve prediction of outcome for horses undergoing laparotomy for treatment of colic.

Effect of omeprazole and sucralfate on gastrointestinal injury in a fasting/NSAID model.

BACKGROUND: Equine gastric ulcer syndrome (EGUS) is a common and significant cause of morbidity in horses, with a range of clinical signs, including inappetence, colic and poor performance. Hospitalised horses are exposed to factors that may induce EGUS, including fasting and nonsteroidal anti-inflammatory drug (NSAID) administration, and may be at risk for development of squamous (ESGD) and glandular gastric disease (EGGD). Prophylactic anti-ulcer medication is often prescribed for these patients, but drug selection is complicated by different aetiology and response to treatment of ESGD and EGGD. OBJECTIVES: To establish the efficacy of sucralfate or omeprazole used prophylactically in horses exposed to a combined feed-fast and NSAID administration EGUS induction protocol. We hypothesised that these drugs would be equally effective for prevention of gastric lesions in the experimental cohort. STUDY DESIGN: Randomised crossover experimental design. METHODS: Horses (n = 14) received either omeprazole (1 mg/kg PO q24h) or sucralfate (20 mg/kg PO q8h) while undergoing the feed-fast/NSAID protocol, allowed an 8-week washout period, and then administered the alternate treatment. Serial gastroscopy, ultrasound and haematology documented treatment effects. RESULTS: ESGD and EGGD score increased over time under both treatments. There was a significant effect of treatment on EGGD scores (P < .001), with post-treatment EGGD scores higher for horses receiving sucralfate (median 3; IQR 2.25,3) than omeprazole (1; 1,1). The effect of treatment on ESGD scores just achieved significance (P = .05), with post-treatment ESGD scores higher for sucralfate (4; 3,4) than omeprazole (2; 2,3). MAIN LIMITATIONS: This study was performed in healthy horses, and response to treatment may differ in horses with clinical illness. Additional investigation in a larger population may be required to detect significant differences in other clinical parameters. CONCLUSIONS: Omeprazole was superior to sucralfate for mitigating gastric lesion severity in healthy horses exposed to a feed-fast/NSAID model.