Thromboelastographic evaluation of hemostatic function in dogs treated for crotalid snake envenomation

Abstract

Objective: To characterize the overall hemostatic changes in dogs envenomated by crotaline snakes via kaolin-activated thromboelastography (TEG), and to determine any prognostic/monitoring value from a TEG tracing on presentation, as well as during treatment with antivenom therapy.

Design: Prospective observational, cohort study.

Setting: University teaching hospital and primary emergency hospital.

Animals: Thirty-eight dogs envenomated by crotaline snakes.

Interventions: TEG tracings were evaluated on presentation to the hospital (pre) as well as immediately following (post) and 12 hours (12 h post) after antivenom treatment, if administered.

Measurements and main results: At presentation, data were available for 38 dogs envenomated by crotaline snakes. Twenty dogs were in Group 1 (Antivenin [Crotalidae] Polyvalent antivenom), 12 dogs were in Group 2 (Antivipmyn antivenom), and 6 dogs in Group 3 that were not treated with antivenom. The average number of vials administered to group 1 and 2 were equal at 2.2. On presentation, based on a G value < TEG reference range, 15/38 (39%) of the dogs had hypocoagulable TEG tracings. There was a significant increase in G and MA value from the pre and 12 hour post measurement (P = 0.0001 and 0.0003, respectively), as well as from the post to 12 hour post measurement (P = 0.003 and, 0.014, respectively). During the study, 5 of 38 dogs died (13%) and of the dogs that died, 4/5 (80%) had angle and MA equal to zero on presentation. A decreased G and MA were significantly associated with mortality (P = 0.02 and 0.04, respectively).

Conclusions: A hypocoagulable TEG tracing, particularly a decreased G value and MA, is associated with an increased mortality in crotaline snake envenomation. G and MA also demonstrate a significant increase over treatment time.

Keywords: TEG; coagulopathy; snake bite.