says, "generic show open ." says, " very dangerous drug if on mouth hands or noses." a powerful ... and dangerous drug is showing up on valley streets.and law enforcement agencies across the country are calling it an "unprecedented law enforcement agencies

>> and it is the canine units on the front lines in the war on drugs who are especially at risk as ashley dimartino reports. says, "you have not just a partner but it's almost your best friend" the fight against d >> it's almost your best friend. >> reporter: the fight against drugs getting harder by the day as more synthetic ones hit the market and access gets easier. >> fentanyl is synthetic opiate. people are familiar with heroin and prescription pills. >> reporter: becoming deadly for these guys. s. if fentanyl gets loose, a dog could absorb it or sniff it up. >> it's pure poison. >> reporter: in order to keep them safe, training has changed