This La Nina cycle has brought plenty of welcome rain. Our gardens are thriving, but so is the local Cane Toad population. These are a persistent fear of many pet owners and justifiably so: Bufo Marinus is easy for pets to catch, has a potent and rapidly active venom, and can find it’s way into the most enclosed and urban of backyards. Here’s the story of a patient with a life-threatening fetish for lunching on toad.
‘Georgie’ Crawford, a 5-year-old Jack Russell, is typical of her breed. She loves scouting around undergrowth, sniffing for live game.
Her owner, Gaynor, was rudely woken at 1am when ‘Georgie’ was first struck down with toad poisoning. On return from a late night toilet excursion she was initially drooling and a little disorientated, within minutes she fell into convulsions. It was 25 minutes before intravenous valium was administered to calm her seizuring brain, by which time her body temperature had already reached 42C.
Fitting, like shivering, generates body heat and any animal with a sustained high temperature, irrespective of cause, can run the risk of a fatal downward spiral of DIC. Lucky for Georgie, minutes after quelling the seizures her temperature had fallen by a full degree.
Ambulanced to vet’s bedside and placed on a drip; her heart was slowed with beta-blockers. Valium wasn’t sufficiently long-acting for Georgie’s toad poisoning and only pentabarbitone could offer sustained relief from the toxic excitation of her brain.
During her 12-hour barbiturate coma her bloodstream was ‘clensed’ by intravenous fluids, and any remaining toxin in her bowel trapped with activated charcoal.
On emergence from her long, deep sleep, Georgie’s heart rhythm and body temperature were back to normal but one pupil remained constricted to a pin-point, unresponsive to light. There were 2 possible explanations: uveitis – an injury to the eye while fitting; or a brain injury like a stroke.
After another 24-hours, with her eye returned to normal, Georgie was ready to go home with both vet and owner assuming she’d learnt her lesson. About 10 days later the whole drama happened again. Dead toad in yard, fitting, valium, drip, barbiturate, and full recovery. Gaynor is now busily toad-proofing her courtyard, and her ‘little monkey’ is always kept on a short lead.
Most of us would expect a dog to learn and it’s likely, given sufficient episodes, even ‘Georgie’ Crawford would eventually control her urges. Don’t be complacent though, even dogs grown bored of toads can unexpectedly rediscover an interest if another dog is competing for the same resource. Such a dog was ‘Zephyr’ Ma: The Fainting Cougher
The creamy, sticky poison is released from the glands on the neck, and can spray up to several metres when the toad is threatened. The venom is usually absorbed when toads are mouthed, or if secretion contacts the eye. Toads bathing in water bowl can also create a delightful, toxic infusion.
There are hundreds of bioactive chemicals in the venom, but the most important fractions are
1. Cardioactive Bufotoxins – these toxins result in abnormal heart contraction and rhythm
2. Adrenaline – the same hormone that raises heart rate and blood pressure when in flight-or-fight mode. This will augment the cardiovascular toxicity of bufotoxins, above, and contribute to psychic effects.
3. Indolealkylamines – psychoactive compounds that can result in the hallucinogenic properties of toad venom, and possibly the kick that Georgie’s after.
In summary this toxic cocktail aims to kill by putting heart and brain into overdrive. A toad victim will appear in a state of excitation, not sedated or groggy. Cat’s exhibit the same symptoms as dogs, but are poisoned far less frequently.
SYMPTOMS AND TIMING
Immediate: Bufovenom appears bad-tasting, causing distress, hypersalivation, head and mouth shaking, face rubbing or eye irritation. These are soon followed by….
3 – 30 minutes: Restlessness, pacing, disorientation, dilated pupils, and deep, cherry-red gums. Possibly vomiting if a toad is swallowed. A small dose of venom may stop here.
5 – 180 minutes: If a larger dose is absorbed. Collapse, rapid and irregular heart and respiratory rates, seizures, hyperthermia. Death can occur within 15 minutes, often on-arrival at the vet.
Depending on dose of venom absorbed, the whole episode will be over within hours. Many pet owners question whether their dogs poor health, over weeks or months, could be due to toads. The answer: not unless your dog has taken to licking them daily.
Timing is one of the most striking features of this disease. The venom is rapid, with a dog typically outdoors only moments before. Any dog observed to mouth a toad, or who exhibits the symptoms listed above, should immediately have their mouth examined, wiped and even hosed out. Irritated eyes should be treated similarly.
This first aid is more imperative than calling the vet. Toad poisoning is one of those rare medical conditions where swift intervention by a pet owner can avert all veterinary involvement and expense, or even better, save your best friend’s life.
- Toad Killer Spray is now available. And you thought pest spray was just for insects. Supposedly more humane than Detol or freezer.
- Much of the technical info here comes from an article published by Mike Fitzgerald of Alstonville
- More on the biology and ecology of toads check out the Wikipedia entry
- Interesting aritcle on the Adaptive Evolution of the Cane Toad in Australia.
- A recent study of the toxicity of dried toads here.
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