Abstract:
OBJECTIVE – To investigate hemostatic changes in dogs envenomed by cytotoxic (African puffadder) and neurotoxic
snakes (snouted cobra) using thromboelastography (TEG) and plasma-based coagulation assays.
DESIGN – Prospective observational clinical study.
SETTING – University teaching hospital.
ANIMALS – Eighteen client-owned dogs; 9 envenomed by African puffadder (Bitis arietans) and 9 by snouted
cobra (Naja annulifera). Ten healthy dogs served as controls.
INTERVENTIONS – None.
MEASUREMENTS AND MAIN RESULTS – Blood was collected at presentation and 24 hours post envenomation.
Platelet count, TEG, prothrombin time, activated partial thromboplastin time (aPTT), antithrombin activity, and
fibrinogen (Fib) and C-reactive protein (CRP) concentrations were measured. Outcomes were analyzed using
linear mixed models at 5% significance. At presentation, R time was significantly prolonged in the puffadder
group compared to the cobra (P = 0.01) and control groups (P = 0.05). Platelet count was significantly lower
in the puffadder compared to the cobra (P = 0.04) and control groups (P = 0.001), respectively. Antithrombin
activity was significantly decreased in the puffadder (P = 0.002) and cobra groups (P = 0.004) compared to the
control group. Both prothrombin time and activated partial thromboplastin time were significantly prolonged
in the cobra group compared to the control group (P = 0.03 for both). The TEG variables, maximum amplitude
(MA) and G, were significantly increased 24 hours post envenomation in the puffadder group compared to their
values at presentation (P = 0.05 for both). Fib and CRP concentrations were significantly increased 24 hours
post envenomation in both snake-envenomed groups.
CONCLUSIONS – Prolonged clot initiation was a common feature in puffadder-envenomed dogs at presentation
and this was likely venom induced. Snouted cobra-envenomed dogs were normo- to hypercoagulable
at presentation. Dogs from both puffadder and cobra groups progressed to a more hypercoagulable by
24 hours post envenomation, most likely due to marked inflammation as indicated by the increased Fib and
CRP concentrations. TEG proved a sensitive tool for detecting abnormal hemostasis in snake-envenomed dogs.
