A sign warns pedestrians not to pet dogs working with Secret Service officers at the corner of Pennsylvania Avenue and 17th Street NW near the White House in Washington, Wednesday, July 9, 2014. The ... more 
A sign warns pedestrians not to pet dogs working with Secret Service officers at the corner of Pennsylvania Avenue and 17th Street NW near the White House in Washington, Wednesday, July 9, 2014. The Secret Service has started deploying specialized canine units to help protect the area around the White House grounds, where tourists flock day and night to catch a glimpse of 1600 Pennsylvania Ave. Although the Secret Service has used police dogs since 1976 to pre-screen areas for presidential visits, this is the first time they’re being broadly deployed among the general public. (AP Photo/Charles Dharapak) less 
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Associated Press | Photo By Charles Dharapak
Wed, Jul 9, 2014 3:09 PM EDT