Some Australian snakes, such as the mulga snakes and tiger snakes, have venom containing myotoxins that cause rhabdomyolysis with muscle pain, tenderness and weakness, a rapidly rising creatine kinase and myoglobinuria. Ptosis is usually the first sign, then facial and bulbar involvement progressing to paralysis of the respiratory muscles and peripheral weakness in severe cases. Neurotoxic envenoming causes a progressive descending flaccid paralysis. Postsynaptic neurotoxins competitively block acetylcholine receptors but the effect can be reversed by antivenom. This takes days to resolve and does not respond to antivenom. Presynaptic neurotoxins disrupt neurotransmitter release from the terminal axon. Paralysis is a classic effect of snake bite and is due to presynaptic or postsynaptic neurotoxins in the venom. It is not associated with consumption of clotting factors, so fibrinogen and d-dimer levels are normal. Some black snakes (mulga and Collett's snake) cause an anticoagulant coagulopathy, probably due to an inhibitor, that is rapidly reversed with antivenom. Recovering from this takes many hours after venom neutralisation has been achieved with antivenom. This is characterised by very high d-dimers, undetectable fibrinogen, and unrecordable prothrombin time and activated partial thromboplastin time. The venom contains a prothrombin activator that leads to consumption of major coagulation factors including fibrinogen, resulting in a defibrination coagulopathy which should be referred to as venom-induced consumptive coagulopathy. The majority of dangerous Australian snakes cause a procoagulant coagulopathy. Bites from some snakes such as whip snakes ( Demansia species) can cause immediate significant local swelling and pain. 4 Local effectsīrown snake bites have minimal local effects, whereas local pain, swelling and occasionally tissue injury can follow black and tiger snake bites. These range from non-specific effects (nausea, vomiting, headache, abdominal pain, diarrhoea, dizziness and collapse) to major organ effects (coagulopathy, neurotoxicity, rhabdomyolysis or renal damage). With more significant envenoming there may be local or systemic effects. In many snake bites only local effects occur because insufficient venom is injected or the snake is non-venomous.
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