Elevated coagulation factors in rabbits (Oryctolagus cunniculus) following brown recluse envenomation (Loxoceles reclusa)

Abstract number: CD004

Mcglasson D., Harroff H. H., Dick E., Sutton J.

59th Clinical Research Squadron, USA

The original purpose of this study was to explore whether dapsone, currently considered the treatment of choice for brown recluse spider (BRS) bite was superior to other medications. The BRS bite causes a necrotizing skin cellulitis. The treatments didn't work well in controlling the necrotizing problem in our rabbit study group of 44 animals who received a dose of BRS toxin. We did find drastically elevated APTT and fibrinogen levels at 72 h. We found the increased APTT did not correct with mixing studies. We studied the intrinsic factors VIII, IX–XII and saw great increases at 72 h from the baseline specimens in the FVIII, FIX and FXI factors. We followed up this protocol with a study on 36 additional animals. One group received a saline injection, and the others a 4.0 or 10.0 µg mL^-1L dose of the BRS venom. Samples were collected at baseline, 24, 48 and 72 h for CBC/platelets and coagulation testing. The WBC counts and platelets decreased drastically at 24 h in rabbits receiving the toxin. The APTT, fibrinogen both clottable and antigenic, FV, FVII, FVIII, FIX, FX, antithrombin and alpha-2 antiplasmin were greatly increased. FII, FXI and FXII showed no significant increase at any time. In humans, the BRS bite may cause DIC with low fibrinogen levels. In the rabbit several factors were elevated but we still had a prolonged APTT. A further study is underway to determine this phenomenon. We now know that we may have an animal model for producing increased coagulation factors in these species following BRS injections.