2 - Envenomation - Snakes & Lizards.pdf

21/09/2022 Envenomation – Snakes & Liazrds •1 Locate & Review • The lymphatic system & its function • Review the nervous system, especially the neuromuscular junction • Review the clotting cascade • Review relevant articles •2 Brown Snakes Western Brown Eastern Brown •3 1 21/09/2022 Easte...

21/09/2022 Envenomation – Snakes & Liazrds •1 Locate & Review • The lymphatic system & its function • Review the nervous system, especially the neuromuscular junction • Review the clotting cascade • Review relevant articles •2 Brown Snakes Western Brown Eastern Brown •3 1 21/09/2022 Eastern Brown • Found throughout the eastern half of mainland Australia. • Fast‐moving, aggressive and known for their bad temper – eastern brown & other brown snakes responsible for more deaths every year in Australia than any other group of snakes. • Venom is ranked as the second most toxic of any land snake in the world • They thrive in populated areas, particularly on farms in rural areas with mice • If disturbed, the eastern brown raises its body off the ground, winding into an 'S' shape, mouth gaping open and ready to strike. • Venom causes progressive paralysis and stops the blood from clotting – may take many doses of antivenom • Victims may collapse within a few minutes. •4 Western Brown • Found widespread over most of mainland Australia – not found in the wetter fringes of eastern Australia or and south‐western Western Australia. • Less aggressive than its eastern cousin • Western browns tend to be fast moving and nervous in temperament – will run for cover, striking quickly if cornered • Venom is not as toxic as the eastern brown's – deliver three times as much – Bites are usually painless &difficult to see due to the small fang marks. • Victims will experience headache, nausea, abdominal pain, severe coagulopathy (blood clotting disorder) and sometimes kidney damage. •5 Clinical Features of Brown Snake Envenomation • Brown snake venom contains pre and post‐ synaptic toxins just as Tiger snake venom does, strangely CF do not regularly show signs of neurotoxicity (ptosis, paralysis, etc) • Procoagulant activity is often the biggest sign (VICC) – Risk of major haemorrhage • Renal impairment, possibly by direct nephrotoxicity •6 2 21/09/2022 Taipans Inland taipan Coastal taipan •7 Inland Taipan • The inland taipan (Oxyuranus microlepidotus) is more deadly than the coastal taipan and, drop‐for‐drop, produces the most lethal poison of any snake in the world. • Found in the arid deserts of central eastern Australia – no human death has been reported from its bite • The taipan is a specialist mammal hunter so its poison is specially adapted to knock out warm‐blooded furry creatures • In a single strike, a taipan can inject 60mg of venom ‐ enough to quickly paralyse a small marsupial but also more than enough to wipe out several human adults. • Has – neurotoxins • paralysis, – myotoxins • procoagulant toxin •8 Clinical Features of Taipan Envenomation • • • • • • • • Pain and swelling at bite site Nausea/vomiting Paralysis Convulsion (especially in children) Coagulopathy (VICC), often profound Mild myolysis Possibility of secondary kidney damage Before 1956 when taipan AV was introduced bites were nearly always fatal •9 3 21/09/2022 Black Snakes Mulga snake (King Brown) Collett’s black snake Red-bellied black snake •10 Clinical Features of Black Snake Envenomation • • • • • Headache Nausea & vomiting Abdominal pain Swelling around bite site Myolysis (can have severe secondary rhabdomyolysis) • Mild anticoagulant effects • Minimal to mild neurotoxic effects (but are very rare) •11 Death Adders •12 4 21/09/2022 Clinical Features of Death Adder Envenomation • • • • • • • Headache Nausea & vomiting Swelling around bite site Progressive weakness Ptosis Slurred speech Profound paralysis with respiratory loss •13 Tiger Snakes •14 Clinical Features of Tiger Snake Envenomation • • • • • • • • Headache Nausea & vomiting Abdominal pain Swelling around bite site Progressive weakness and paralysis Ptosis Slurred speech Myolysis, dark urine (myoglobinurea) •15 5 21/09/2022 Copperhead Snake •16 Clinical Features of Copperhead Snake Envenomation • Venom from the copperhead is less well characterised • Symptoms can be similar to tiger snake • Venom contains pre‐ and postsynaptic toxins • Mild to severe risk of paralysis • May cause myolysis • Coagulopathy is less certain •17 LIZARDS •18 6 21/09/2022 Gila Monster • Venom produced in glands of lower jaw (upper jaw in snakes) • No confirmed reports of fatalities after 1939, and those prior to that year are questionable due to the primitive dangerous "treatments." Gila Monster •19 Mexican Beaded Lizard •20 Australian Lace Monitor • Recent Discovery! • Venom and peptides from the Australian Lace monitor, commonly known as a goanna, shown to have various properties – Decrease blood pressure – Clotting ability •21 7 21/09/2022 Any Questions •22 8