Purr. Whirr.

Martha Armstrong of the Humane Society of the United States is dead set against frivolous modifications. "If someone is creating a designer dog or cat that fits your lifestyle so you don't sneeze," she believes you might not be cut out to be a pet owner.

She says, "Who are we doing this for? Certainly not for the benefit of the animal. Healthy dogs and cats are being destroyed. Someone wants to manipulate a dog or cat to make it fit into their lifestyle, or clone a new animal simply because they want a replica, they are not going to get what they are looking for, and there are going to be a lot of discards as a result of trying to."

All of the talk about cloning and gene-manipulation reminds Armstrong of a Mark Twain witticism: "If man could be crossed with the cat, it would improve man, but it would deteriorate the cat."

In "The 6th Day," Schwarzenegger's character asks the slippery pet-clone salesman if he will be able to trust the replicated dog -- "a large animal with large teeth" -- to be gentle with his daughter.

The salesman smiles. "We can make him smaller if you want, with softer teeth. We can even color-coordinate him to match your decorating scheme."

From his Wisconsin lab, Damiani says he is focusing on cloning for now. "Eventually," he says, "there is the possibility to do genetic modification when we do cloning. We clone from cultured cells and that gives us the opportunity to modify the DNA in those cells, then screen the cells to see if the modification worked and then use the new cells to clone with."

Using the petri dish instead of the age-old stud/bitch process that has given us Australian cattle dogs that know how to nip at the heels of cows and German shorthair pointers that are natural-born hunters, scientists will be able to: put the breeding process on super-fast forward; work with purebred cats, which have always been as difficult to manage as, well, a herd of cats; and create heretofore-unimagined combinations and recombinations.

You want a "pooset hound," with the curly coat of a poodle and the ears of a basset hound? How about a "Great Daneshund" with the body of a dachshund and the legs of a Great Dane?

Susan McCarthy, author of "Becoming a Tiger: How Baby Animals Learn to Live in the Wild," imagines a near-future in which even endangered species -- the wild cats and antelopes that Dresser is already cloning -- will be running around the urban apartment. She sees the possibility of tiny gorillas and two-foot-high giraffes.

The history of animal companions is long and complicated and full of surprises. In some cultures, cheetahs have been kept as pets and wolves have been raised like dogs. So turning wolves into little purse pups and feral jungle cats into bike-basket kitties makes perfect -- or imperfect -- sense. Can't you just see ptiny pterodactyls in Parisian bird cages and genetically defanged rattlesnakes playing with the kids in the sandbox? Michael Crichton, courtesy phone.

In the near future, "our pets could start looking alien and strange to some people," says bioethicist Caplan. "But that would already be true for the Hittites, the Assyrians and the Han Chinese. They wouldn't recognize our pets."

Some recognized breeds date back only a few years. The American hairless terrier line began in the 1970s, the British Victorian bulldog in the 1980s.