Systematic evaluation supports the use of ELISA for quantification of calprotectin in equine feces, a first step toward noninvasive quantification of intestinal inflammation in horses.

OBJECTIVE: To optimize and evaluate methods for the detection of the inflammatory biomarkers myeloperoxidase (MPO) and calprotectin (CP) in equine feces by ELISA. ANIMALS: Healthy horses (n = 28) and horses with intestinal inflammation (n = 10). METHODS: Feces were suspended in buffer to create fecal supernatant. Serum and fecal supernatant were analyzed using ELISA kits validated for the detection of MPO and CP in equine serum. Assay validation steps included intra- and interassay variability (coefficient of variation [CV]), dilution linearity, spike recovery, and sample type correlation. Variations in sample handling protocols (centrifugation speed, extraction buffer, and filtration) were evaluated. RESULTS: 17 paired fecal and serum samples were used for initial analysis (10 healthy horses, 7 colitis). Previously reported sample handling protocols resulted in detectable MPO and CP but poor CV, linearity, and spike recovery. There was a linear correlation between serum and fecal samples for CP but not MPO. There was a significant difference between the concentration and CV of alternative sample handling protocols for CP and MPO, with improved CV for CP (2.1% to 18.6%) but not MPO (14.4% to 53.4%). Processing fresh feces with a fecal extraction buffer and filtration of supernatant resulted in the best CV (0.5% to 3.8%) and recovery (45% to 64%) for CP. Detection of MPO was inconsistent regardless of method. CLINICAL RELEVANCE: There are few reliable diagnostic modalities for inflammation of the equine large colon. Findings support quantification of CP in equine feces using the described ELISA kit and protocol. With additional study to establish reference interval and clinical utility, the fecal inflammatory biomarker CP may allow for noninvasive quantification of intestinal inflammation in horses.

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.

Comparison of plasma l-lactate between jugular and cephalic veins in healthy and systemically ill horses using a point-of-care device.

OBJECTIVE: To compare plasma l-lactate (LAC) values between samples collected from jugular and cephalic venipuncture in healthy horses and systemically ill horses. DESIGN: Prospective, experimental study. SETTING: Large animal university teaching hospital. ANIMALS: Thirty healthy adult university-owned horses and 43 client-owned horses presenting to the large animal hospital for elective surgical procedures or for emergent medical evaluation of systemic illness. INTERVENTIONS: Blood samples were collected from the jugular vein (JV) and cephalic vein (CV) and placed in EDTA blood tubes prior to any medical therapy. LAC values were obtained with a handheld lactate meter at the time of blood collection. MEASUREMENTS AND MAIN RESULTS: LAC was higher in CV samples than JV samples in healthy horses (P < 0.001); however, all values were within the normal reference range. Similarly, LAC was higher in CV samples than JV samples in systemically ill horses (P < 0.001), but the median JV value was within normal reference range (1.9 mmol/L [17.1 mg/dL]), while the median CV value was outside the normal reference range (2.9 mmol/L [26.1 mg/dL]). CONCLUSIONS: The CV is an alternative venipuncture site for assessing plasma LAC if the JV is not accessible or to preserve the JV for subsequent catheterization. However, in ill horses, the CV value may be outside the reference range when the corresponding JV value would have been within the reference range.

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.

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.

Modeling Challenge Data to Quantify Endogenous Lactate Production.

With the intention of isolating the susceptibility of modeling methodology to influence our investigation of the infusion data, we used three kinetic approaches to our models: a simple approach, a unit approach, and a novel approach. The simple approach used exclusively built-in modeling features of the software in terms of units of the infusion dilution (mmol/L), as well as in terms of the precision of switching the infusion on and off. The unit approach used the same switching mechanism as the simple approach, but the units were modeled in those of the infusion (e.g., mmol/kg). Thirdly with the novel approach, we used an automated approach to controlling the infusion, in the sense that as the modeling mechanism sensed the slowdown of the infusion, it was gradually turned off. The units of the analysis for the novel approach were exactly the same as those deployed in the unit approach. Our objective here was to see if common pharmacokinetic parameters were seriously impacted by the particular modeling method.

Repeatability and accuracy of fingertip pulse oximeters for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate in anesthetized dogs breathing 100% oxygen.

OBJECTIVE: To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in anesthetized dogs breathing 100% O2. ANIMALS: 29 healthy client-owned anesthetized dogs undergoing various surgical procedures. PROCEDURES: In randomized order, each of 7 FPOs or a reference pulse oximeter (PO) was applied to the tongue of each intubated anesthetized dog breathing 100% O2. Duplicate measurements of oxygen saturation (Spo2) and PR were obtained within 60 seconds of applying an FPO or PO. A nonparametric version of Bland-Altman analysis was used. Coefficient of repeatability was the interval between the 5th and 95th percentiles of the differences between duplicate measurements. Bias was the median difference, and the limits of agreement were the 5th and 95th percentiles of the differences between each FPO and the PO. Acceptable values for the coefficient of repeatability of Spo2 were ≤ 6%. Agreements were accepted if the limits of agreement had an absolute difference of ≤ ± 3% in Spo2 and relative difference of ≤ ± 10% in PR. RESULTS: Coefficient of repeatability for Spo2 was acceptable for 5 FPOs, but the limits of agreement for Spo2 were unacceptable for all FPOs. The limits of agreement for PR were acceptable for 2 FPOs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that some FPOs may be suitable for accurately monitoring PRs of healthy anesthetized dogs breathing 100% O2, but mild underestimation of Spo2 was common.

Normal regression of the internal umbilical remnant structures in Standardbred foals.

BACKGROUND: Diseases affecting the internal umbilical remnant are common in foals. Ultrasound is used to diagnose abnormalities of these structures, and to monitor treatment. However, little is known about the progression of normal internal umbilical remnant regression. OBJECTIVES: To document normal regression of the umbilical remnant in foals over the first 6 weeks of life. STUDY DESIGN: Prospective, longitudinal cohort study. METHODS: Weekly ultrasound examinations were performed beginning at 1 day of age in 34 healthy Standardbred foals. The umbilical vein was measured in cross section just cranial to the external umbilicus, at the level of the liver and midway between these points. The umbilical arteries were measured in cross section just caudal to the external umbilicus, at the apex of the bladder and at the midpoint of the bladder. The urachus was imaged longitudinally as it exited the bladder. Reduction in size over time was evaluated as percentage change in diameter. RESULTS: Structure diameter decreased linearly over time. The largest measurements were at 24 hours of age with a median umbilical vein diameter of 0.83 cm (IQR 0.77-1.02 cm), median umbilical artery diameter of 0.61 cm (IQR 0.56-0.70 cm) and median urachal diameter of 1.07 cm (IQR 1.02-1.14 cm). There was a significant reduction in diameter for all structures (16.0%-21.9%; corrected P < .001) within the first week of life. MAIN LIMITATIONS: All foals were of a single breed, and examinations and measurements were performed by multiple individuals. CONCLUSIONS: The internal umbilical remnants (umbilical vein/arteries, and urachus) rapidly regress over the first few weeks of life. The median internal umbilical remnant diameters reported here are smaller than previously reported values, emphasising the importance of accounting for age when diagnosing umbilical abnormalities. In a healthy Standardbred foal, normal structures are difficult to definitively identify via transcutaneous ultrasound by 5-6 weeks of age.

Congenital phimosis causing preputial swelling in a newborn foal.

An 18-hour-old colt was presented for abdominal discomfort, preputial swelling, and frequent posturing to urinate. Examination of the scrotum confirmed 2 testes and no scrotal or inguinal hernia. Transabdominal ultrasound identified a distended bladder and no free fluid in the peritoneal cavity. Inspection of the preputial cavity revealed that the internal lamina of the prepuce was mostly attached to the glans penis. The preputial cavity was lubricated and manual traction was applied to detach the internal lamina of the prepuce from the glans penis. The colt urinated spontaneously 1 hour after the procedure, and the preputial swelling slowly resolved over 7 days. Key clinical message: Congenital phimosis in a newborn foal was resolved by manual separation of the penile epithelium and preputial lamina.

Phimosis, une cause d'oedème du prépuce chez un poulain nouveau-né. Un poulain de 18 heures de vie a été examiné en raison d'un inconfort abdominal, d'un oedème du prépuce et d'une mise en position fréquente pour uriner. L'examen du scrotum a confirmé la présence de deux testicules et l'absence d'hernie scrotale ou inguinale. Une échographie abdominale a permis de confirmer une vessie dilatée et l'absence de liquide dans la cavité péritonéale. L'examen de la cavité préputiale a révélé que la couche interne du prépuce était complètement attachée au gland du pénis. La cavité préputiale a été lubrifiée et une traction manuelle a été appliquée à la couche interne du prépuce pour la détacher du gland du pénis. Le poulain a recommencé à uriner spontanément une heure après la procédure et l'oedème du prépuce s'est résorbé sur une période de sept jours.Message clinique clé :Le phimosis congénital chez un nouveau-né a été résolu par séparation manuelle de l'épithélium pénien et de la lame préputiale.(Traduit par les auteurs).

The area under the curve of L-lactate in neonatal foals from birth to 14 days of age.

BACKGROUND: Prior studies have shown the prognostic utility of measuring L-lactate in critically ill neonatal foals, both as single (at admission) and serial measurements. Greater prognostic sensitivity and specificity may be achieved by use of the area under the L-lactate versus time curve (LACArea ) over the first 24 hours of hospitalization, which captures both severity and duration of hyperlactatemia. Prior to application of this concept in sick equine neonates, a reference interval for LACArea should be determined. METHODS: The concentration of lactate [LAC] was measured in blood obtained via direct jugular venipuncture from clinically normal foals on Days 1 (birth-24 h of age), 3, 7, and 14 following birth at 6-hour intervals for each 24-hour period. LACArea was calculated using the trapezoidal method. Differences in LACArea by Day were determined by MANOVA with a priori Bonferroni correction, P ≤ 0.05. RESULTS: LACArea differed by Day (P = 0.001), being largest on Day 1, followed by Day 3. Days 7 and 14 were smallest and not different from each other. CONCLUSION: LACArea decreases substantially and predictably over the first week of life in normal neonatal foals. Knowing how LACArea normally changes over the first 2 weeks of life will aid in future study of LACArea as it applies to sick neonatal foals, allowing for consideration of maturational changes potentially unrelated to disease.

Defining the Systemic Inflammatory Response Syndrome in Equine Neonates.

Defining and describing the systemic inflammatory response syndrome (SIRS) and sepsis facilitated recognition and investigation of the complex disease processes involving the host response to infection and trauma. Over the years a variety of definitions of SIRS have been examined and applied to numerous research studies to improve critical care in both human and veterinary clinical practice. This article summarizes the history of the development of the SIRS definition, outlines the pathophysiologic processes that are involved in SIRS, and provides a specific definition for use in foal medicine.

Prognostic Indicators for Survival and Athletic Outcome in Critically Ill Neonatal Foals.

Equine neonatal intensive care units have expanded knowledge and understanding of the normal and abnormal physiology of the equine neonate, resulting in successful treatment of critically ill equine neonates. The overall survival rate has increased tremendously since the early 1980s, from a little more than 50% to 80% or more for most facilities. The severely septic foal and the very premature foal still remain large treatment challenges, but less severely septic foals and foals challenged by adverse peripartum events such as dystocia and placentitis are surviving to hospital discharge and performing to the owners' expectation in larger numbers.

Update on interstitial pneumonia.

Interstitial pneumonias encompass a wide variety of acute and chronic respiratory diseases and include the specific diseases equine multinodular pulmonary fibrosis and acute lung injury and acute respiratory distress. These diseases have been diagnosed in all age groups of horses, and numerous agents have been identified as potential causes of interstitial pneumonia. Despite the varied causes, interstitial pneumonia is uniformly recognized by the severity of respiratory disease and often poor clinical outcome. This article reviews the causal agents that have been associated with the development of interstitial pneumonia in horses. Pathophysiology, clinical diagnosis, and treatment options are discussed.

Evaluation of contact activation of citrated equine whole blood during storage and effects of contact activation on results of recalcification-initiated thromboelastometry.

OBJECTIVE: To evaluate the degree of activation of the contact pathway in citrated equine whole blood over holding times ≤ 30 minutes and assess effects of contact activation on recalcification-initiated thromboelastometry. ANIMALS: 11 healthy adult mixed-breed horses. PROCEDURES: Blood was collected by atraumatic jugular venipuncture into prewarmed evacuated siliconized glass tubes containing citrate anticoagulant and held at 37°C for ≤ 30 minutes. Thromboelastometry was performed with an in vitro viscoelasticity (thromboelastometry) monitoring system. Factor XII and factor XI procoagulant activities were determined in contemporaneously collected platelet-poor plasma samples by assessing changes in turbidity for 1 hour at approximately 25°C, with clotting times calculated by fitting a line to the steepest segment of the absorbance curve and determining its intersection with baseline. Effect of holding time on thromboelastometry parameters and plasma enzyme activity was evaluated by repeated-measures ANOVA on ranks. Association of procoagulant activities with coagulation time was determined by Spearman rank-order correlation analysis. RESULTS: Thromboelastometry parameters (coagulation time, clot formation time, α angle, and maximum clot firmness) reflected significant increases in coagulability during the holding period. Factor XII and factor XI procoagulant activities were significantly increased at 30 minutes, compared with 2 or 10 minutes (indicating contact activation of samples), and had significant negative correlation with coagulation time. CONCLUSIONS AND CLINICAL RELEVANCE: Ex vivo activation of the contact system in equine whole blood was evident, suggesting that recalcification of blood in the absence of a trigger is not an acceptable method of assessing the hemostatic system in horses.

Comparison of radiographic and computed tomographic images of the lungs in healthy neonatal foals.

OBJECTIVE: To compare CT and radiographic images of the lungs in sedated healthy foals positioned in sternal recumbency and to investigate whether a relationship exists between CT-derived measurements of lung attenuation and Paco2 and Pao2. ANIMALS: 6 healthy Standardbred foals < 14 days of age. PROCEDURES: Thoracic CT images were acquired followed by radiographic views with each foal sedated and positioned in sternal recumbency. For each foal, both CT and radiographic images were evaluated for severity and extent of changes by lung regions on the basis of a subjective scoring system by 3 investigators. Quantitative analysis of CT images was also performed. Assessments of Pao2 and Paco2 were performed before sedation, following sedation prior to CT, and after CT prior to radiography. RESULTS: Interobserver agreement for CT and radiographic image scoring was strong (0.73) and fair (0.65), respectively; intraobserver agreement was near perfect for CT (0.97) and radiographic (0.94) image scoring. Increased CT attenuation and radiographic changes were identified for all foals and were preferentially distributed in the caudoventral portion of the lungs. Radiographic scores were significantly lower than CT image scores. A positive correlation (r = 0.872) between lung attenuation and CT image score was identified. A significant increase in Paco2 was not considered clinically relevant. Significant changes in Pao2 were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that interpretation of CT images may be less subjective, compared with interpretation of radiographic images. These findings may aid in the evaluation of CT and radiographic images of neonatal foals with respiratory tract disease.

Qualitative and quantitative interpretation of computed tomography of the lungs in healthy neonatal foals.

OBJECTIVE: To qualitatively describe lung CT images obtained from sedated healthy equine neonates (≤ 14 days of age), use quantitative analysis of CT images to characterize attenuation and distribution of gas and tissue volumes within the lungs, and identify differences between lung characteristics of foals ≤ 7 days of age and foals > 7 days of age. ANIMALS: 10 Standardbred foals between 2.5 and 13 days of age. PROCEDURES: Foals were sedated with butorphanol, midazolam, and propofol and positioned in sternal recumbency for thoracic CT. Image analysis software was used to exclude lung from nonlung structures. Lung attenuation was measured in Hounsfield units (HU) for analysis of whole lung and regional changes in attenuation and lung gas and tissue components. Degree of lung attenuation was classified as follows: hyperinflated or emphysema, -1,000 to -901 HU; well aerated, -900 to -501 HU; poorly aerated, -500 to -101 HU; and nonaerated, > -100 HU. RESULTS: Qualitative evidence of an increase in lung attenuation and patchy alveolar patterns in the ventral lung region were more pronounced in foals ≤ 7 days of age than in older foals. Quantitative analysis revealed that mean ± SD lung attenuation was greater in foals ≤ 7 days of age (-442 ± 28 HU) than in foals > 7 days of age (-521 ± 24 HU). Lung aeration and gas volumes were lower than in other regions ventrally and in the mid lung region caudal to the heart. CONCLUSIONS AND CLINICAL RELEVANCE-Identified radiographic patterns and changes in attenuation were most consistent with atelectasis and appeared more severe in foals ≤ 7 days of age than in older neonatal foals. Recognition of these changes may have implications for accurate CT interpretation in sedated neonatal foals with pulmonary disease.

Exogenous L-lactate clearance in adult horses.

OBJECTIVE: To determine endogenous production of L-lactate and the clearance of exogenous sodium L-lactate (ExLC) in healthy adult horses. DESIGN: A sodium L-lactate solution (1 mmol/kg body weight qs to 500 mL final volume in 0.9% NaCl) was adminstered IV over 15 minutes. Blood samples for L-lactate concentration [LAC] measurement were collected immediately prior to infusion, at 5, 10, and 15 minutes during infusion and at 1 minute intervals for 15 minutes, at 30, 45, 60, 120, and 180 minutes postinfusion. Disposition modeling and pharmacokinetic analysis was performed using proprietary software. SETTING: University Teaching Hospital. ANIMALS: Six clinically healthy adult horses. MEASUREMENTS AND MAIN RESULTS: Median (range) baseline [LAC] was 0.43 (0.20-0.72) mmol/L for samples obtained every 3 hours over the 24 hours prior to ExLC and demonstrated variability primarily associated with horse. Median [LAC] immediately prior to ExLC was 0.43 (0.35-0.52) mmol/L. A 2-compartment model was used to specify the pharmacokinetic parameters. Median (range) ExLC was 1.05 (0.073-1.75) L·h(-1) ·kg(-1) and t(1/2) ß was 29.54 (20.8-38.6) min. Median lactate production based on basal [LAC] immediately prior to ExLC was was 0.49 (0.31-0.93) mmol·h(-1) ·kg(-1) . CONCLUSIONS: ExLC in healthy adult horses is greater than that of hyperlactemic human patients but similar to normolactemic-sick human patients examined using the same model, supporting development of species, and disease specific ExLC parameters.