In Africa they do the same thing for initial detection of tuberculosis.
the patients all call cough onto a growth medium plate and in a couple days the rat races is by all of the plates lined up in a single-file.
The rat stops when it smells a positive plate.
That’s an interesting application.
I wonder if aflotoxin could be detected?
The father of South African golfer Gary Player worked in a gold mine, 10,000 feet underground. The miners used to share their lunch with the rates to keep them alive and in place. The rats could detect well in advance when a section of the mine was about to collapse. When the miners saw the rats fleeing, they scrambled onto the elevator to get out. Rats were like the “canary in the coal mine” except the rats usually survived.