Hemostatic analysis of dogs naturally envenomed by the African puffadder (Bitis arietans) and snouted cobra (Naja annulifera)

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.

Naja annulifera Snake: New insights into the venom components and pathogenesis of envenomation

“…However, although detected at low abundance in the proteomic analysis, the venom contains SVMP and SVSP able to cleave the fibrinogen alpha chain, which suggests that these proteinases can contribute to the hemostatic alterations as observed in dogs envenomated by N . annulifera [36].…”

“…annulifera . These dogs presented with various clinical findings, including hematologic alterations, such as leukocytosis and thrombocytopenia [34], increased plasma levels of Cardiac Troponin I and C Reactive Protein (CRP) [35] and disturbances in the coagulation system [36].…”

Factor X activating Atractaspis snake venoms and the relative coagulotoxicity neutralising efficacy of African antivenoms

“…Thromboelastography in this study was able to discriminate between procoagulant ( Figure 4A) and pseudo-procoagulant ( Figure 4B) effects. This method, and the thromboelastometry modification, are becoming increasingly important in snake venom research for such studies due to the ability to determine clot strength and accurately quantify specific effects upon clotting (Dambisya et al, 1994(Dambisya et al, , 1995Hiremath et al, 2016;Jackson et al, 2016;Nagel et al, 2014;Nielsen, 2018;Nielsen and Bazzell, 2017;Nielsen and Boyer, 2016;Nielsen et al, 2017a;Nielsen et al, , 2017bNielsen et al, 2018;Oguiura et al, 2014;Strydom et al, 2016).…”

Thromboelastographic evaluation of 2 dogs with boomslang (Dispholidus typus) envenomation

“…[11][12][13] More specific conditions relevant to that presented herein include TEG evaluation of hemostatic function in dogs with DIC, the use of TEG to assess hemostatic changes in dogs naturally envenomed by the African puffadder (Bitis arietans) and snouted cobra (Naja annulifera), and TEG evaluation of dogs bitten by rattlesnakes native to southern California. [14][15][16] The use of TEG in cases of boomslang envenomation in people has been reported; however, to the authors' knowledge, no such reports exist in the veterinary literature. (or sometimes referred to as stage IV of DIC).…”

“…As a result, TEG has grown in popularity and has subsequently been demonstrated to be a useful tool in both the diagnosis and management of various hemostatic abnormalities in dogs, correlating with clinical signs of bleeding 11–13 . More specific conditions relevant to that presented herein include TEG evaluation of hemostatic function in dogs with DIC, the use of TEG to assess hemostatic changes in dogs naturally envenomed by the African puffadder ( Bitis arietans ) and snouted cobra ( Naja annulifera ), and TEG evaluation of dogs bitten by rattlesnakes native to southern California 14–16 …”