No, most drug dogs or sniffer dogs are not trained to detect dexamphetamine - that doesn't mean they wouldn't be able to, it simply means most law enforcement agencies don't train the dogs for that.
See the way it works is a sniffer dog has a hyper sensitive sense of smell. It can easily smell the dexamphetamine on you.
However, to train a dog to find and remember scents, officers hide samples of a drug in training, help the dog to find it, and then give them a treat. The dog learns to go after that smell to get a treat, or gets excited when he senses a whiff of that smell (which he equates with a treat).
For this method to work on dexy, the cops would need to have trained the dog using dexamphetamine, as well as all the usual substances: Cocaine, weed, heroin, MDMA etc...
Usually, they wouldn't even try and teach a dog anything but the most common drugs because that would be too much for a dog to handle.
For example, I went through Sydney airport and past a row of sniffer dogs with some M-cat in my bag, and they didn't look twice at me.
Doesn't mean I didn't crap myself when i saw sniffer dogs.. But that's a different story!
