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.

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.

Differential gene expression analysis reveals pathways important in early post-traumatic osteoarthritis in an equine model.

BACKGROUND: Post-traumatic osteoarthritis (PTOA) is a common and significant problem in equine athletes. It is a disease of the entire joint, with the synovium thought to be a key player in disease onset and progression due to its role in inflammation. The development of effective tools for early diagnosis and treatment of PTOA remains an elusive goal. Altered gene expression represents the earliest discernable disease-related change, and can provide valuable information about disease pathogenesis and identify potential therapeutic targets. However, there is limited work examining global gene expression changes in early disease. In this study, we quantified gene expression changes in the synovium of osteoarthritis-affected joints using an equine metacarpophalangeal joint (MCPJ) chip model of early PTOA. Synovial samples were collected arthroscopically from the MCPJ of 11 adult horses before (preOA) and after (OA) surgical induction of osteoarthritis and from sham-operated joints. After sequencing synovial RNA, Salmon was used to quasi-map reads and quantify transcript abundances. Differential expression analysis with the limma-trend method used a fold-change cutoff of log2(1.1). Functional annotation was performed with PANTHER at FDR < 0.05. Pathway and network analyses were performed in Reactome and STRING, respectively. RESULTS: RNA was sequenced from 28 samples (6 preOA, 11 OA, 11 sham). "Sham" and "preOA" were not different and were grouped. Three hundred ninety-seven genes were upregulated and 365 downregulated in OA synovium compared to unaffected. Gene ontology (GO) terms related to extracellular matrix (ECM) organization, angiogenesis, and cell signaling were overrepresented. There were 17 enriched pathways, involved in ECM turnover, protein metabolism, and growth factor signaling. Network analysis revealed clusters of differentially expressed genes involved in ECM organization, endothelial regulation, and cellular metabolism. CONCLUSIONS: Enriched pathways and overrepresented GO terms reflected a state of high metabolic activity and tissue turnover in OA-affected tissue, suggesting that the synovium may retain the capacity to support healing and homeostasis in early disease. Limitations of this study include small sample size and capture of one point post-injury. Differentially expressed genes within key pathways may represent potential diagnostic markers or therapeutic targets for PTOA. Mechanistic validation of these findings is an important next step.

Differential Gene Expression in Articular Cartilage and Subchondral Bone of Neonatal and Adult Horses.

Skeletogenesis is complex and incompletely understood. Derangement of this process likely underlies developmental skeletal pathologies. Examination of tissue-specific gene expression may help elucidate novel skeletal developmental pathways that could contribute to disease risk. Our aim was to identify and functionally annotate differentially expressed genes in equine neonatal and adult articular cartilage (AC) and subchondral bone (SCB). RNA was sequenced from healthy AC and SCB from the fetlock, hock, and stifle joints of 6 foals (≤4 weeks of age) and six adults (8-12 years of age). There was distinct clustering by age and tissue type. After differential expression analysis, functional annotation and pathway analysis were performed using PANTHER and Reactome. Approximately 1115 and 3574 genes were differentially expressed between age groups in AC and SCB, respectively, falling within dozens of overrepresented gene ontology terms and enriched pathways reflecting a state of growth, high metabolic activity, and tissue turnover in the foals. Enriched pathways were dominated by those related to extracellular matrix organization and turnover, and cell cycle and signal transduction. Additionally, we identified enriched pathways related to neural development and neurotransmission in AC and innate immunity in SCB. These represent novel potential mechanisms for disease that can be explored in future work.