Veterinarians are practicing ever more advanced medicine on the nation?s 77 million dogs, 90 million cats and a myriad of other animals — treatments that vie with the best of human medicine. The driving force is “the changing role of the pet in our society,” said Dr. Patty Khuly, a veterinarian at Miami?s Sunset Animal Clinic. At the University of Wisconsin-Madison School of Veterinary Medicine, a new surgical technique to repair torn knee ligaments in dogs was so successful that it?s now being used on NFL players, said Dr. William Gengler, director of Wisconsin?s Veterinary Medical Teaching Hospital.