Snake Venom Toxins

Neurotoxin

These toxins act on nerves supplying skeletal muscles causing progressive paralysis. It takes time for the venom to reach the nerves and the onset of paralysis is usually delayed for 1-2 hours after envenomation.

Muscles of the face and eyes are particularly susceptible to snake neurotoxin and early signs of neurotoxin effects include drooping of the eyelids (ptosis), double vision (diploplia) and loss of facial expression (ie. unable to smile). Over time the effects spread to involve other muscles in the body, eventually causing weakness of muscles required for breathing and full paralysis

Neurotoxins are typically found in venom of Tiger snakes, Death Adders, Taipans, Copperhead snakes and Rough-Scaled snakes.

Antivenom is effective against post-synaptic neurotoxins (Death Adder) but does not reverse pre-synaptic neurotoxins (Tiger snakes, Taipan)

Myolysin Toxin

These toxins attack muscle cells causing muscle damage resulting in pain in the muscle and weakness. It takes some hours for this to occur and by the time the pain and tenderness is noticed, the damage is irreversible. As muscle damage occurs, the products of muscle damage clog up the kidneys and can cause kidney failure.

Myolysins are typically found in venom of Tiger snakes, Taipans and Sea snakes.

Antivenom has proven effective in reducing muscle pain and reducing muscle cell damage and may protect against kidney damage.

Procoagulant Toxin

These toxins activate blood clotting processes in the blood stream resulting in a rapid consumption and deficiency in essential blood clotting products leading to an uncontrolled bleeding tendency. Bleeding may be observed from the gums or from scratches or cuts in the skin. Blood may also be noticed (and can be tested for) in the urine or faeces. Bleeding may occur anywhere in the body with bleeding in the brain or abdomen frequently responsible for deaths.

Procoagulants are typically found in venom of Brown snakes, Tiger snakes and Taipans.

Antivenom  (often many ampoules) is essential for reversal of the clotting abnormality caused by Brown snakes and Tiger snakes however the clotting abnormalities caused by the Taipanis often self limiting and will resolve within 12 to 18 without treatment.

Anticoagulant Toxin

Unlike the procoagulant toxins that cause bleeding by consumption of clotting factors, anticoagulant toxins act directly to cause excessive bleeding tendency. The effect of the toxin is however identical with bleeding from the gums, skin, urine and faeces.

Anticoagulants are typically found in venom of Mulga snakes.

Nephrotoxin

There are no specific kidney directed toxins isolated from Australian elapid snakes however kidney damage is not rare following significant envenomations. The proposed mechanisms include direct toxic effect of venom on the kidneys as well as secondary damage from poor blood flow, accumulation of damaged muscle proteins or clotting abnormalities affecting the kidneys.

Kidney damage is most frequently seen following envenomation by Brown snakes, Tiger snakes and Taipans.