Don't know about birds, but mammals -- like people -- can sometimes benefit from the services of a skilled chiropractor. They have lower back pain, achy joints, and spinal misalignment just like us humans. But if you find it difficult to imagine your St. Bernard submitting to an adjustment, you haven't met Dr. Gleason. A gentle giant of a man, he's the type of person his patients -- who include cats, dogs, horses, Bengal tigers, even elephants -- take an immediate liking to. Unfazed by squirming bodies and wagging tails, he handles animals with the love and self-assurance of Dr. Dolittle himself, working his magic with confident manipulations. In fact, because of his particular talent, Gleason is so popular -- after all, everyone wants a well-adjusted pet -- that he travels hundreds of miles throughout the Bay Area each week to handle appointments at clinics and vets' offices. For a prime East Bay time slot, try early Saturday at VCA Hospital in Oakland.