From October 1996 through September 1997, U.S. Customs Canine Enforcement Teams were involved in over 9,200 narcotic or currency related seizures. The street value of the narcotics uncovered by the canines exceeded $3.1 billion. The dogs detected approximately 417,762 pounds of marijuana, 888 pounds of hashish, 48,238 pounds of cocaine, 326 pounds of heroin, 335 pounds of hash oil, 213 pounds of opium, 303,380 drugs (pills, capsules, etc.), and $12,021,142 in currency.

They only have a few specificly trained dogs to go after certain types of pills, but those focus mostly on Extacy. I think the pills they did seize were either amphetemines or opiates. Benzo's and the likes are safe from dogs as far as I know. If I'm wrong someone please correct me. You would think that at the moment they're training almost all dogs for anti-terror stuff (radiation, explosives, ect).