Introduction

Heatstroke (HS) is a devastating condition, with reported mortality rates of 40–50%. Excessive activation of the coagulation system, potentially culminating in overt DIC, is a prominent feature of HS. Thromboelastometry (TEM) is a viscoelastic diagnostic modality providing global assessment of the clotting process, enabling determination of hyper-, normo-, or hypo-coagulable states.

Objectives

To investigate changes in TEM and its utility as a prognostic tool in dogs with naturally-occurring HS at different time points during the initial 48 hours.

Methods

Forty-two client-owned dogs presented to the emergency service for HS were included. Blood samples for CBC, serum chemistry, coagulation panel and TEM were drawn at presentation, and q 12–24 hours post presentation. A previously reported HS severity score was calculated. Complications, namely AKI, DIC and death were recorded. Dogs euthanized on presentation based on a no-treatment intent were excluded.

Results

Median time from heat insult to presentation was significantly longer in non-survivors (2 vs. 4.5 h, P≤0.05), while prior cooling did not affect survival. Mortality rate was 31% and a higher HS severity score accurately predicated non-survival. Significant differences between survivors and non-survivors were apparent mainly on intrinsic-TEM and included prolongations in clotting times, a lower alpha angle and increases in maximal lysis in non-survivors, on presentation and\or 12–24 hours post-presentation (P<0.05 for all). Based on the AUC value (area under the curve from test start until maximal clot formation is reached), non-survivors were significantly more likely to have a hypo-coagulable TEM tracing compared to survivors, both on presentation (55 vs. 15%, P=0.029) and 12–24 h post-presentation (41 vs. 0%, P=0.026), respectively. A hypo-coagulable TEM tracing was significantly associated with AKI, DIC and a higher HS severity score (P<0.05 for all).

Conclusions

In dogs with HS, changes in TEM indicated that non-survivors were significantly more likely to develop a hypo-coagulable state, as reflected by their AUC value. In 21% of the dogs, coagulation derangements were minimal on presentation, and became apparent over the first 12–24 hours, highlighting the need for close monitoring and serial measurements of coagulation parameters. A hypocoagulable AUC value was significantly associated with mortality, severity score and complications.

E-mail: kelmere1@gmail.com