That is a really neat article. I bet the little dog gets a double take when they bring him out to sniff for drugs.
I had never actually seen a sniffer dog until last year when we went to a Cowboys/Browns game and they had dogs out sniffing for explosives in cars that were parking in the VIP area. I think that it would be easier to have sniffer dogs that are smaller.
It makes perfect sense! They are such a smart breed, can get into smaller places and it is incredibly expensive to train these dogs and chihuahuas live much longer than larger breeds so would make more financial sense. I love it!