When looking for pet services (dog walking, sitting, training) in NYC, I recommend using a professional service that has licensed employees. Look for firms that have bonded and insured professionals working for them.
One firm I would recommend looking into is Dog Boy NYC (http://dogboynyc.com/
). Owned by a Certified Professional Dog Trainer and Canine Behavior Counselor, they work together with a network of vets, groomers, sitters, day care centers and pet stores. They provide excellent services for all your pet needs.