Chicago dogs have the second-busiest bowels in the nation, according to a new study.Dog walkers working with Rover, a site where dog owners can find walking and grooming services, pick up 700 pounds of dog poop per month in the city, Rover says. That number blows past even Los Angeles and New York City, which both post figures of 400 pounds of poop picked up per month.The two cities surpassing Chicago are Seattle and Denver. Walkers in those cities pick up about 1,000 pounds of poop every month.The "busiest" dog breeds in Chicago are labrador retrievers, poodles and beagles, Rover says.Rover came to these conclusions by tracking potty breaks dogs take while out on walks with Rover walkers. Walkers with the site pick up about 2,000 pounds of poop every day throughout the country, the site says.