The Urban Hound has come a long way from its one-person dog-walking roots. Today, the biz caters to its canine clientele with a doggy hotel that accommodates 50, custom training packages, day care services and indulgent grooming treatments. Despite its growth during the past decade, the staff keeps a “staying small” mindset, providing one-on-one attention to the animals whenever possible and still focusing on those daily walks—existing South End and Back Bay routes will soon be joined by runs in Southie.