A dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. Stray dogs are adopted by the police from a municipal anti-rabies centre and then trained to help the police patrol the streets, and search for drugs, explosives and weapons. (Photo by Daniel Becerril/Reuters)





A dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





Dog trainers work with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





Police officers look on as a dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A dog trainer works with previously abandoned dogs at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A dog trainer (not pictured) works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A police officer and his re-trained dog wait at a security checkpoint in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





Police officers and his re-trained dog inspect a vehicle at a security checkpoint in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A police officer and his re-trained dog inspect a bus at a security checkpoint in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A police officer and his dog, an adopted stray that has been re-trained, inspects the area while checking the trailer of a truck at a security checkpoint in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)





A dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. (Photo by Daniel Becerril/Reuters)