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Signs of Snake Bite in Dogs

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The variation in presenting signs between animals may relate to the particular dose of venom as well as to the snake species involved.

For example, dogs injected with low doses of tiger snake venom subcutaneously did not show the pre-paralytic signs (salivation and vomiting) nor muscle paralysis, but they did suffer from mydriasis and photophobia for several days. After the injection of near lethal doses, vomiting and salivation occurred within 2 hours and pupils were dilated by 4 hours. Dogs which received multi-lethal doses developed pre-paralytic signs in 5-30 minutes, mydriasis by 2-4 hours and they were severely paralysed. They died between 2.5-5 hours after the venom was injected.

Although muscle paralysis was not detected when low doses of venom were given, there was clear evidence of severe muscle damage. Doses as low as a quarter of a lethal dose caused widespread rhabdomyolysis with plasma creatine kinase commencing to rise about two hours after the venom was injected. On the other hand, no extension of the clotting time or defibrinogenation occurred unless a dose exceeding five lethal doses was injected. Note that coagulopathy may be more prominent after brown or taipan snake bites compared with tiger snake envenomation.

Since widespread muscle damage can occur with sub-lethal doses and the animal will take days to recuperate, consideration could be given to administering antivenom to any dog that has had contact with a tiger snake. Indeed, megaoesophagus, a consequence of rhabdomyolysis, has been described in dogs envenomated several days previously by tiger snakes and subsequently treated with antivenom.

Snake bite in dogs due to other snakes has not been as well researched. One study reported that the main clinical sign in dogs bitten by death adders was severe lower motor neuron paralysis with no evidence of coagulopathy or myopathy. A case of red-bellied black snake envenomation resulting in intravascular haemolytic anaemia, rhabdomyolysis and anuric renal failure has been reported.

One could possibly expect rhabdomyolysis to occur after bites by most of the dangerous snakes, except brown snakes (genus Pseudonaja) and death adders (genus Acanthophis).

(References: Heller et al. 2006 Aust. Vet. J. 85: 158-162; Swindells et al. 2006 Aust. Vet. J. 84: 22-29)