LUK

A thromboelastographic study on antemortem, postmortem and in vitro lipopolysaccharide inoculated whole blood in crocodilians

Rune Lizard & Kasper Alvarez
Copenhagen University

Background

Several case-reports of fatal septicemia in crocodilians have been reported; however, none evaluated the hemostatic state of the patients. Evaluating hemostatic disorders in reptiles is challenging as there are no validated hemostatic assays in these species. Thromboelastography (TEG) is able to identify alterations in global hemostasis and is used to diagnose, characterize and guide treatment of hemostatic disorders. The aim of the study was to validate TEG in crocodilians and to assess tissue-factor (TF), kaolin and avian thromboplastin (AThr) as activators of TEG (hypothesis 1). Citrated whole blood (CWB) samples were obtained from 29 clinically healthy crocodilians (Crocodylus niloticus n = 20, Crocodylus mindorensis n = 4, other Crocodylidae n = 5). Blood was sampled both antemortem (AM) and postmortem (PM) to evaluate applicability of blood samples from recently deceased crocodilians (hypotheses 2). A complete blood count (CBC) was performed on all individuals from the main study. Furthermore, to assess potential alterations during septicemia in crocodilians, an in vitro study was conducted by inoculating whole blood with lipopolysaccharide (LPS) from E. coli O111:B4 in concentrations of 10 and 250 µg/mL prior to a TEG analysis (hypothesis 3).

Results

Ranges from thromboelastography parameters in AM samples were as follows: R = 4.0-16.3min, K = 0.8-2.9min; ⍺-angle = 56.2-79.2°, MA = 57.8-75.3mm and G = 6.8-15.2kdyn/cm2. Antemortem samples showed prolonged R-times compared to most other domestic and exotic animal species. Postmortem samples were pre-activated, characterized by short R and K times and increased ⍺-angle. Maximum amplitude and shear elastic modulus strength remained unchanged in PM samples.

Conclusions

We were not able to induce a hemostatic response with LPS in the concentrations investigated (P > 0.05). A protocol for kaolin-activated TEG has been established and validated. The reported ranges of TEG parameters from both AM and PM whole blood samples may provide institutions that wish to examine hemostasis in crocodilians with clinical guidelines to aid in the diagnosis of hemostatic disorders.