Coagulopathy in the equine critical care patient

Coagulation Profile of the Healthy Miranda's Donkey

Miranda's donkey, originating in northern Portugal, is an autochthonous breed that is deeply intertwined with the region's culture and economy. Knowledge of the physiological characteristics of the breed is important for its preservation, and several studies have been carried out, but none have focused on its coagulation profile. The aim of this study was to establish reference intervals (RIs) for coagulation in healthy Miranda's donkey and to assess the influence of sex and age. Blood samples from 75 clinically healthy animals were analyzed for seven coagulation parameters: four using IDEXX ProCyte Dx and three using Start® 4-Diagnostica-Stago. The RI values were calculated following the ASVCP guidelines and with the Reference Advisor V.2.1 software. To analyze the influence of sex and age, SPSS version 29 was used. No significant differences were found between sexes (p > 0.05), but statistically significant differences were found between ages (p < 0.05) for platelet count and plateletcrit (both higher in young animals). The RIs described here can help monitor health and guide the diagnosis and treatment of diseased Miranda's donkeys, contributing to their preservation. Our study encourages further research on coagulation in donkeys and the use of different methodologies to obtain information for veterinarians working with this species.

Assessment of thrombin generation in horses using a calibrated automated thrombogram

BACKGROUND

The amount of thrombin generated reflects the endogenous thrombin potential (ETP), which depends on the balance of pro- and anticoagulant factors. The calibrated automated thrombogram (CAT) allows for the direct measurement of thrombin generation during the clotting process.

OBJECTIVES

(1) To describe the results of the CAT assay in horses, (2) to establish intra-assay and intra- and interindividual variation of thrombin generation in healthy horses, and (3) to compare in vitro low-molecular-weight heparin (LMWH) sensitivity between healthy and sick horses. The hypothesis for the last objective is that inhibition of thrombin generation in sick horses requires higher heparin concentrations.

METHODS

The plasma of 10 healthy mixed breed horses was used for the determination of normal thrombin generation parameters (lag time, time to peak, peak thrombin concentration, and ETP). Five of the healthy horses were compared with five horses with systemic inflammatory response syndrome (SIRS). In vitro heparin sensitivity was determined using LMWH.

RESULTS

The intra-assay variation was small (<5%) for all parameters. Relatively large intra- and interindividual variation were observed in healthy horses. Four of the five sick horses with SIRS had a thrombogram compatible with a hypercoagulable state. The in vitro heparin sensitivity test suggested decreased sensitivity to LMWH in hypercoagulable states.

CONCLUSIONS

The CAT assay could detect coagulopathy in horses. In vivo experiments are needed to confirm that it can be used to monitor responses to LMWH therapy.

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.

Coagulation Assessment in the Equine Patient

Horses with clinical signs of unprovoked or excessive hemorrhage should be evaluated for underlying platelet defects or coagulopathies. This article provides an overview of preliminary screening and definitive tests to assess coagulation and identify hemostatic defects in horses, as well as a review of the hemostatic disorders most frequently encountered in clinical practice.

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.

EFFECT OF ε-AMINOCAPROIC ACID ON FIBRINOLYSIS IN PLASMA OF ASIAN ELEPHANTS (ELEPHAS MAXIMUS)

ε-Aminocaproic acid (EACA) is a lysine analogue antifibrinolytic drug used to treat bleeding disorders in humans and domestic animals. Use in zoological medicine is rare and dose recommendations are anecdotal, but EACA may be a valuable therapeutic option for bleeding disorders in exotic species, including Asian elephants ( Elephas maximus ). This study used an in vitro model of hyperfibrinolysis and a thromboelastograph-based assay to estimate the therapeutic plasma concentration of EACA in Asian elephants (61.5 μg/ml, 95% CI = 34.6-88.5 μg/ml). Substantial but incomplete inhibition of lysis was seen at relatively low concentrations of EACA (40 μg/ml). Asian elephants appear sensitive to EACA-mediated inhibition of hyperfibrinolysis. Doses published for domestic animals, targeting higher plasma concentrations, may be inappropriate in this species.

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.

Coagulopathies in horses with colic

The most common coagulopathy in horses with colic is a hypercoagulable state associated with disseminated intravascular coagulation. The intensity of this coagulopathy depends on the severity and duration of the gastrointestinal lesion, with the ischemic and inflammatory problems and peritonitis being the most frequently affected by coagulopathies. Early initiation of prophylactic therapy significantly reduces the severe hypercoagulable state in horses with intestinal conditions which are recognized to be at high risk for disseminated intravascular coagulation. In addition to the systemic coagulopathy observed in horses with colic, a peritoneal coagulopathy independent from that occurring in blood has been observed, and its recognition and assessment may have clinical usefulness in the diagnosis of the gastrointestinal diseases and outcome.

Enteritis and colitis in horses

Enteritis and colitis remain challenging and life-threatening diseases despite many recent advances. Successful treatment is largely dependent on early recognition and directed therapy, which is facilitated by obtaining a complete history and physical examination. A number of new therapies and methods of monitoring critically ill patients have become integral components of treatment success. The critical monitoring of equine foals and adults continues to be an exciting and emerging field.

Pharmacokinetics and pharmacodynamics of ε-aminocaproic acid in horses

OBJECTIVE

To determine the pharmacokinetics and pharmacodynamics of epsilon-aminocaproic acid (EACA), including the effects of EACA on coagulation and fibrinolysis in healthy horses.

ANIMALS

6 adult horses.

PROCEDURES

Each horse received 3.5 mg of EACA/kg/min for 20 minutes, i.v. Plasma EACA concentration was measured before (time 0), during, and after infusion. Coagulation variables and plasma alpha(2)-antiplasmin activity were evaluated at time 0 and 4 hours after infusion; viscoelastic properties of clot formation were assessed at time 0 and 0.5, 1, and 4 hours after infusion. Plasma concentration versus time data were evaluated by use of a pharmacokinetic analysis computer program.

RESULTS

Drug disposition was best described by a 2-compartment model with a rapid distribution phase, an elimination half-life of 2.3 hours, and mean residence time of 2.5 +/- 0.5 hours. Peak plasma EACA concentration was 462.9 +/- 70.1 microg/mL; after the end of the infusion, EACA concentration remained greater than the proposed therapeutic concentration (130 microg/mL) for 1 hour. Compared with findings at 0 minutes, EACA administration resulted in no significant change in plasma alpha(2)-antiplasmin activity at 1 or 4 hours after infusion. Thirty minutes after infusion, platelet function was significantly different from that at time 0 and 1 and 4 hours after infusion. The continuous rate infusion that would maintain proposed therapeutic plasma concentrations of EACA was predicted (ie, 3.5 mg/kg/min for 15 minutes, then 0.25 mg/kg/min).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that EACA has potential clinical use in horses for which improved clot maintenance is desired.