Fitdog in Santa Monica offers excellent dog training and boarding, but best of all is its list of hiking trails for dogs and their humans in Greater L.A. From a dog's perspective, we've chosen the not-yet-overrun Westridge Trail hike. It's a hidden gem that begins at the dead end of a road that winds through an attractive, upscale Brentwood neighborhood. The hike offers interesting city views of skyscrapers in Century City and beyond. But what the dogs really love is peering over the weedy edge of the trail (really a dirt road) into the shadowed ravines of Sullivan Canyon, and running through the low chaparral after small beasts. Leashes are not required. On a recent day, a Portuguese water dog, twin Dalmatians and several mutts zipped up the trail, technically known as Mandeville Fire Road. It's part of the "Big Wild," billed as the biggest natural area inside any city in the United States. 2652 Westridge Road, Brentwood.