Coagulopathies in horses with colic

Critical Care of the Colic Patient: Monitoring, Fluid Therapy, and More

A successful outcome to management of the critical colic patient is highly dependent on how the patient is monitored and treated, particularly, in the perioperative period. In this article, we will provide an update on monitoring techniques, advances in fluid therapy, nutrition management and pharmacotherapeutic agents, inclusive of pain monitoring and management, prokinetics, and management of systemic inflammatory response syndrome and the hypercoagulable state.

A pilot study evaluating the Calibrated Automated Thrombogram assay and application of plasma-thromboelastography for detection of hemostatic aberrations in horses with gastrointestinal disease

Background

Critically ill horses, such as horses with gastrointestinal (GI) disease, often suffer from hemostatic aberrations. Global hemostatic tests examining the initiation of coagulation, clot strength and fibrinolysis, such as the Calibrated Automated Thrombogram (CAT) and plasma-thromboelastography (TEG) have not been evaluated in horses. This study aimed to evaluate CAT and apply plasma-TEG in horses.

Test performance of CAT was evaluated on equine platelet poor plasma with intra- and inter-assay variability (CV) and a heparin dilution curve. To examine clinical performance of both tests, group comparisons were assessed comparing healthy horses, horses with mild and severe GI disease with both CAT and plasma-TEG.

Results

For CAT, intra- and inter-assay CVs were established for lag-time (1.7, 4.7%), endogenous thrombin potential (1.6, 4.6%), peak (2.6, 3.9%) and time to peak (ttPeak) (1.9, 3.4%). Increasing heparin concentrations led to the expected decrease in thrombin generation. In the group comparison analysis, CAT showed significant higher peak (p = 0.04) and ttPeak (p = 0.008) in the severe GI disease group compared to horses with mild GI disease and healthy horses, respectively. Plasma-TEG showed an increased angle (p = 0.032), maximum amplitude (p = 0.017) and shear elastic force (G) (p = 0.017) in the severe GI disease group compared to healthy horses.

Conclusions

CAT performed well in horses. Both CAT and plasma-TEG identified hemostatic aberrations in horses with severe GI disease compared to healthy horses. Further studies including more horses, are needed to fully appreciate the use of CAT and plasma-TEG in this species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03058-7.

Pharmacokinetics and pharmacodynamics of intravenous and oral apixaban in horses

Large vessel and microvascular thrombi are common complications in systemically ill horses contributing to patient morbidity and mortality. Apixaban, an oral factor Xa inhibitor, shows excellent efficacy against stroke and deep vein thrombosis in humans. The purpose of this study was to determine serum apixaban concentrations and anti-factor Xa activity in horses after orally administered apixaban. Five horses received a single dose of intravenous (0.09 mg/kg) and oral (1 mg/kg) apixaban in a cross-over design. Serum apixaban concentrations and anti-Xa activity were measured serially via liquid chromatography-tandem mass spectrometry and a commercial assay, respectively, for 12 hr following oral administration. Apixaban was detected in all horses after both oral and intravenous administration. Oral administration yielded a mean maximum concentration of 60.3 ng/ml (59.4-111 ng/ml), mean time to maximum concentration of 0.5 hr (0.5-2), mean half-life of 6.2 hr (4.6-8.3), and mean oral bioavailability of 10% (3.8-17.4). After oral administration, anti-Xa activity had a strong positive relationship with serum apixaban and was best represented by a dose-response model with the following parameters: E₀  = 5.00 ng/ml, E_MAX  = 311 ng/mL, EC₅₀  = 267 ng/ml, and n = 1.58. Anti-Xa activity was significantly higher 2 hr post-administration compared with baseline (p = .032). Despite low oral bioavailability, administration of 1 mg/kg oral apixaban, in healthy horses, achieves serum concentrations similar to those reported in humans. Apixaban has potential clinical utility in horses and warrants further investigation.

MMP-9 Concentration in Peritoneal Fluid Is a Valuable Biomarker Associated with Endotoxemia in Equine Colic

The purpose of the study was to compare the results of sepsis scoring (clinical examination and clinical pathology) to the concentrations of matrix-metalloproteinases (MMPs) -2, -8, and -9; tissue-inhibitor of metalloproteinases (TIMPs) -1 and -2; and inflammatory chemokines interleukin (IL) 1β and tumor-necrosis-factor-alpha (TNF-α) in plasma and peritoneal fluid of equine colic patients. A modified sepsis scoring including general condition, heart and respiratory rate, rectal temperature, mucous membranes, white blood cell count (WBC), and ionized calcium was applied in 47 horses presented with clinical signs of colic. Using this scoring system, horses were classified as negative (n = 32, ≤6/19 points), questionable (n = 9, 7-9/19 points), or positive (n = 6, ≥10/19 points) for sepsis. MMPs, TIMPs, IL-1β, and TNF-α concentrations were evaluated in plasma and peritoneal fluid using species-specific sandwich ELISA kits. In a linear discriminant analysis, all parameters of sepsis scoring apart from calcium separated well between sepsis severity groups (P < 0.05). MMP-9 was the only biomarker of high diagnostic value, while all others remained insignificant. A significant influence of overall sepsis scoring on MMP-9 was found for peritoneal fluid (P = 0.005) with a regression coefficient of 0.092, while no association was found for plasma (P = 0.085). Using a MMP-9 concentration of >113 ng/ml in the peritoneal fluid was found to be the ideal cutoff to identify positive sepsis scoring (≥10/19 points; sensitivity of 83.3% and specificity of 82.9%). In conclusion, MMP-9 was found to be a biomarker of high diagnostic value for sepsis and endotoxemia in equine colic. The evaluation of peritoneal fluid seems preferable in comparison to plasma. As abdominocentesis is commonly performed in the diagnostic work-up of equine colic, a pen-side assay would be useful and easy-to-perform diagnostic support in the decision for therapeutic intervention.

Expression of Proteinase-Activated Receptor 2 During Colon Volvulus in the Horse

Large colon volvulus in horses is associated with a poor prognosis, especially when ischemic-reperfusion injury of the affected intestinal tract develops. Proteinase-activated receptor 2 (PAR₂) plays an important role in the pathogenesis of inflammation in the gastrointestinal tract. The aim of this study was to evaluate the distribution and expression of PAR₂ in colonic pelvic flexure of horses spontaneously affected by large colon volvulus (CVH group). Eight horses admitted for severe abdominal colon volvolus and which underwent surgery were included. Colon samples were collected after enterotomy. Data previously obtained from healthy horses were used as a control group. Histologic evaluation was carried out to grade the severity of the colon lesions. Immunofluorescence, western blot and quantitative polymerase chain reaction (RT-qPCR) were carried out on colon samples to evaluate PAR₂ expression. In addition, the transcriptional profile of cytokines and chemokines was evaluated using RT² Profiler™ PCR Array Horse Cytokines & Chemokines. Three out of the eight patients were euthanised due to clinical deterioration. Immunostaining for PAR² was observed in the enterocytes, intestinal glands and neurons of the submucosal and myenteric plexi. In the CVH horses, the expression of PAR₂ mesenger RNA (mRNA) did not differ significantly from that of the healthy animals; western blots of the mucosa of the colon tracts showed a clear band of the expected molecular weight for PAR₂ (~44 kDa) and a band smaller than the expected molecular weight for PAR₂ (25kDa), suggesting its activation. The gene expressions for C-X-C motif ligand 1 (CXCL1); interleukin 8 (IL8), macrophage inflammatory protein 2 beta (MIP-2BETA) were upregulated in the colic horses as compared with the colons of the healthy horses. Therefore, in the present study, the expression and activation of PAR₂ in the colons of horses in the presence of an inflammatory reaction like that occurring in those with spontaneous colon volvulus was confirmed.

Clinical, hematologic, hemostatic, and serum biochemical findings related to survival in Arabian horses with colic

BACKGROUND

The efficacy of clinical examinations, and hematologic, hemostatic, and serum biochemical assessments to determine appropriate early medical or surgical therapy in Arabian horses with colic have not been well-described.

OBJECTIVES

We aimed to evaluate clinical and hematologic findings, coagulation-fibrinolytic parameters, and organ dysfunction markers in association with survival in horses with colic.

METHODS

Seventeen Arabian horses with colic and ten healthy horses were enrolled. After clinical examinations, including heart rates (HRs), capillary refill times (CRTs), abdominal sounds, rectal palpations, and nasogastric (NG) reflux assessments in both healthy and diseased horses, blood samples were collected and hematologic parameters, coagulation indices such as the prothrombin time (PT), activated partial thromboplastin time (APTT), plasma d-dimer (PDD), platelet count, fibrinogen, and hepatorenal biomarkers were measured. Based on the outcomes, horses with colic were divided into survival (10) and nonsurvival (7) groups, and all mentioned parameters were compared with the control group horses.

RESULTS

Unlike HRs, CRTs, and abdominal sounds, rectal palpations (57.1%) and NG reflux (28.6%) findings were least sensitive in being able to determine survival. At least three of the five coagulation indices were significantly abnormal (prolonged PT, increased PDD, and decreased plasma fibrinogen) in 71.4% of the horses in the nonsurvival group compared with the control and survival groups. Significantly increased urea, creatinine, and bilirubin levels, and AST activities were also observed in the survival group compared with the control and nonsurvival groups.

CONCLUSIONS

The combination of prolonged PT, increased PDD, and hypofibrinogenemia could be a reliable predictor of survival in horses with colic. The significant renal and hepatic dysfunctions in nonsurviving horses with colic appeared to be consistent with disseminated intravascular coagulation (DIC) and a grave prognosis.

Assessment of the CoaguChek-XS portable prothrombin time point-of-care analyzer for horses

Coagulopathies in horses are common and potentially life-threatening. In equine field medicine, a portable point-of-care (POC) prothrombin time (PT) testing device could be useful to identify early changes in extrinsic clotting. The CoaguChek-XS (Roche Diagnostics) is a small, portable POC PT analyzer used in human medicine. Our preliminary study assessed the suitability of CoaguChek-XS for testing PT in horses and established the PT reference interval (PT RI) in healthy horses using this instrument. Blood samples collected from 102 healthy and ill horses were analyzed with the CoaguChek-XS and compared to a semi-automated coagulometric analyzer (SACA) as the gold standard. There was a significant positive correlation between the 2 measurement methods ( r = 0.765, p < 0.01), and very good agreement, with 97% of the samples falling within limits of agreement. The mean CoaguChek-XS PT coefficient of variation was 0.8%, indicating high precision. With high precision and good agreement with the coagulometric PT, the CoaguChek-XS should be further validated for PT measurement in horses.

Proteinase-activated receptor 2 distribution and expression in equine small intestine tracts following herniation through the epiploic foramen

Proteinase-activated receptor 2 (PAR₂) is a G-protein-coupled receptor for trypsin and mast cell tryptase; it is highly expressed at the intestinal level with multiple functions, such as epithelial permeability and intestinal motility. The aim of the study was to evaluate the distribution and expression of proteinase-activated receptor 2 in the small intestine during herniation through epiploic foramen. In this prospective clinical study, eight horses admitted for colic and which underwent exploratory laparotomy were considered. During surgery, the jejunum or the ileum was sampled by enterectomy. Morphological examination (histology, PAR₂ immunohistochemistry) and molecular biology analysis (western blot and quantitative polymerase chain reaction) were carried out on the resected intestinal samples. The Marginal Injured Tracts (MITs) and Central Injury Tracts (CITs) were defined as the oral and caudal marginal segments of the resected bowel tract and as the geometric centre of the intestinal ischaemic lesion length, respectively. The PAR₂ immunoreactivity was particularly evident in the epithelial cells, with higher immunoreactivity in the MIT rather than in the CIT. Moreover, a different immune localisation was observed in the MITs at the cell membrane level and in the CITs in the cytoplasm. No statistical difference was observed in PAR₂ mRNA and protein (44kDa) expression between the MIT and the CIT. The PAR₂ protein content in the intestinal tracts which were removed from horses with herniation was lower when compared with the control animals. This study provided data concerning the PAR₂ presence and distribution in horses with intestinal herniation through the epiploic foramen.

Progression of plasma D-dimer concentration and coagulopathies during hospitalization in horses with colic

OBJECTIVE

To assess the progression of plasma D-dimer concentrations and coagulation status in horses with different types of colic.

DESIGN

Prospective clinical observational study performed between March 2004 and September 2008.

SETTING

Veterinary university teaching hospital.

ANIMALS

Horses admitted and treated for colic and hospitalized for >48 hours were considered. Animals were classified by diagnosis into medical obstructive conditions (MO), surgical obstructive conditions (SO), inflammatory conditions, and ischemic lesions (IS).

INTERVENTIONS

Three blood samples were obtained from each horse (admission, at 24-48 h [or after surgery] and upon discharge). For each sample, plasma D-dimer concentration, prothrombin time, activated partial thromboplastin time, antithrombin activity, and the presence of subclinical disseminated intravascular coagulation were determined.

MEASUREMENTS AND MAIN RESULTS

When median plasma D-dimer concentration values at admission and after 24-48 hours were compared, they were different but stable in horses with MO (1.29-1.95 nmol/L) and inflammatory conditions (5.70-6.69 nmol/L). However, 10-fold and 5-fold increases were observed, respectively, in SO (2.08 to 16.38 nmol/L) and IS (3.08 to 15.91 nmol/L) in the postoperative period. By 24-48 hours, the percentage of horses with coagulopathy increased in most groups (MO, 43 to 58%; SO, 50 to 96%, IS, 53 to 90%). By the time of discharge, 87% of horses with SO problems and 89% of horses with IS still had some form of coagulopathy documented.

CONCLUSIONS

Throughout hospitalization, horses with MO problems had less severe coagulopathy and lower plasmatic D-dimer concentrations compared to other groups of horses. On admission, most horses with inflammatory conditions presented with coagulopathy. At 24-48 hours of hospitalization and following surgery, the hemostatic profile can differ markedly when compared to admission values.

Proteinase-activated receptor 2 expression in the intestinal tract of the horse

Proteinase-activated receptor 2 (PAR2) is a G-protein-coupled receptor for trypsin and mast cell tryptase; it is highly expressed at the intestinal level with multiple functions, such as epithelial permeability and intestinal motility. Many proteases activate PAR2 during tissue damage, suggesting a role of the inflammatory response receptors. The aim of the study was to evaluate the distribution and expression of PAR2 in the jejunum, the ileum and the pelvic flexure, using samples collected from healthy adult horses after slaughter. Proteinase-activated receptor 2 immunoreactivity (PAR2-IR) was observed in the enterocytes, intestinal glands, the smooth muscle of the muscularis mucosae, and the longitudinal and circular muscle layers; there were no differences in the distribution of PAR2-IR in the different sections of the intestinal tract. The protein expression level showed that the relative amount of the PAR2 content in the mucosa of the intestinal tract decreased from the small to the large intestine while the PAR2 mRNA analysed showed similar values. This study provides relevant findings concerning the distribution of the PAR2 in the intestines of healthy horses and represents the starting point for evaluating the role of the PAR2 during strangulative intestinal disease and consequent systemic intestinal reperfusion/injury complications in horses in order to identify and employ antagonist PAR2 molecules.

Anesthesia for the horse with colic

This article discusses anesthesia for horses with colic from acute gastrointestinal disease. Emphasis is placed on new developments in pre-, intra-, and immediate postoperative management over the last decade, including early goal-directed therapy (EGDT) in the resuscitation of septic patients, the controversy over the optimal fluid type to administer, and the management of complications, such as cardiovascular depression, hypoventilation and hypoxemia, and decreased colloid oncotic pressure (COP). An update on analgesia is also provided; older drugs such as ketamine and lidocaine are increasingly being recognized both for their analgesic properties and other potentially beneficial effects in endotoxemic horses.

Coagulation profiles of healthy Andalusian donkeys are different than those of healthy horses

BACKGROUND

Coagulation disorders are frequently diagnosed, especially in hospitalized equidae, and result in increased morbidity and mortality. However, hemostatic reference intervals have not been established for donkeys yet.

OBJECTIVES

To determine whether the most common coagulation parameters used in equine practice are different between healthy donkeys and horses.

ANIMALS

Thirty-eight healthy donkeys and 29 healthy horses.

METHODS

Blood samples were collected to assess both coagulation and fibrinolytic systems by determination of platelet count, fibrinogen concentration, clotting times (prothrombin time [PT] and activated partial thromboplastin time [aPTT]), fibrin degradation products (FDP) and D-Dimer concentrations.

RESULTS

PT and aPTT in donkeys were significantly (P < .05) shorter than those of horses. In contrast, FDP and D-Dimer concentrations were significantly (P < .05) higher in donkeys than in horses.

CONCLUSIONS AND CLINICAL IMPORTANCE

The coagulation parameters most commonly determined in equine practice are different in donkeys compared with horses. Thus, the use of normal reference ranges reported previously for healthy horses in donkeys might lead to a misdiagnosis of coagulopathy in healthy donkeys, and unnecessary treatments in sick donkeys. This is the first report of normal coagulation profile results in donkeys, and further studies are warranted to elucidate the physiological mechanisms of the differences observed between donkeys and horses.