Sniffing around

I've been spending a lot of time in airports in the last few months and I've been seeing a lot more cops with dogs than I used to within the US - presumably sniffing for bombs. Used to be they only sniffed for drugs. I've been wondering myself if the same dogs now sniff for both. Thanks to JackL who discovered this research paper paid for by the feds entitled "K9 Units in Public Transportation: A Guide for Decision Makers," we all know that the answer is no. In fact, the trainers say it's impossible to train for both as then they are not able to find either item.