I found this interesting in the news that dogs used to sniff for drugs at airports are being significantly cut back here in the US due to the increased legality of marijuana at the state level (though technically still illegal at the federal level) and passengers arriving from Canada. A large number of the dogs are being put into early retirement.
I learned that dogs can be trained to sniff for drugs but once they "learn" a smell, they cannot unlearn it. Basically, there is no difference to them between marijuana or cocaine or meth. It's either a yes or no in their noses.
So new dogs are being trained (at an estimated $25,000 a pop). Interesting.
Things we learn in life.
Rub a Dub