If we eliminated the dog from our lives, nothing much would happen to our ecology. Independent of man, the dog is a vandal. With man, he does a little sheep-herding, a little watch-dogging. He helps law enforcement officers control the troublesome ghetto-dwellers and protest marchers. He sniffs out "hash"and "grass."He goes out on weekends and helps man murder other forms of life for pleasure. But mostly he is just an adjunct to man's ego . . . The cat owes man nothing. Some experts estimate that there is one homeless cat managing on its own for every one with a home, which makes a total cat population in the U.S. of more than fifty million. That means the largest nonhuman animal population in the nation, short of rodents, whose number is beyond estimate. Eliminate cats from our ecology and, in a matter of weeks, we would be overrun by rodents.