The best way to kill a cane toad is freezing it, research says - but it's currently illegal

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Sometimes the old ways are the best.

Putting a cane toad in the freezer next to the ice cream is the best way to humanely kill the animal, according to the latest research.

This method was called into question when some suggested ice crystals could form in the body causing the cane toad pain.

However, the latest research, which involved putting censors in a toad’s brain, shows the method is humane.

Cane toads are killed in their thousands in Australia every year, some by community toad-busting groups.

“We need to offer a humane death to the toads,” says Rick Shine, from the University of Sydney’s School of Biological Sciences. “It’s not their fault they were brought to Australia 80 years ago.”

He is lead author on research showing that the once-popular method, currently outlawed nationally and internationally by animal ethics committees as inhumane, is actually a simple and ethical way to kill a toad.

The research by the University of Sydney, Monash University and the University of Wollongong is published in the journal, Biology Open.

The researchers implanted small data-loggers in the brains of cane toads to measure pain responses. They then put the toads into a refrigerator for a few hours, before transferring them to a household freezer. The toads quietly slipped into unconsciousness as they froze, and their brains did not register any evidence of pain.

“This procedure was a widespread method for humanely killing amphibians and reptiles for many years until about 20 years ago, but animal ethics committees decided it was inhumane because the animals’ toes might freeze while their brains were still warm enough to detect pain,” says Professor Shine.

“However, our work shows that in cane toads at least, the toad just drifts off into torpor as it cools down, and its brain is no longer functioning by the time its body begins to freeze.”

The research provides a simple solution to a difficult dilemma for the Australian community in areas that struggle with large populations of cane toads, such as the Kimberley region of Western Australia, the Darwin region of the Northern Territory and coastal Queensland.

Current ethics regulations recommend that people kill cane toads by hitting them on the head with a hammer. But a slight misjudgment could result in severe pain for the toad and a splash of toxic poison up into the hammer-wielder’s eyes.

“Popping toads into the fridge for a few hours to cool down then moving them to the freezer beside the ice cream is kinder and safer for everyone involved,” says Professor Shine.

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