Seeing Double? The Facts about Cloning | Dog & Cat Health, Wellness, Products and Breed Information

Seeing Double? The Facts about Cloning
| Print | By Caroline Coile | May 19, 2009 2:04 PM

Dogs and cats have a fatal flaw--they don't live long enough. For many pet owners, they'd pay anything to keep their dogs with them forever. Now you can put your money where your heart is, and have your pet cloned. But it won't be cheap.

Cat cloning has been available for several years, with a price tag of about $32,000. Only a handful of cat owners took advantage of a second life (or would that be a tenth life for an animal that's already spent nine?) for their cats, however, before the company that offered it, Genetic Savings and Clone, closed its doors. But dog cloning has only become available this year, in Korea, and at a much higher price -- $150,000.

It's not that dogs are more valuable or missed than cats, or that owners are paying by the pound. The high price tag reflects the difficulty of cloning a dog. And it's a deal compared to the $19 million that a wealthy owner spent trying to make his husky mix, Missy, the first cloned dog. After seven years American researchers gave up when they were beat to the punch by South Korean researchers who cloned an Afghan Hound named Snuppy (short for Seoul National University puppy).

The American researchers weren't inept; they were able to clone a cat (CC, for Carbon Copy) on the second attempt, back in 2002. It's just that dog reproductive physiology makes dog cloning the most difficult of any mammal attempted (read on for why). The South Korean researchers implanted 1,095 eggs in 123 surrogate mothers, resulting in only three pregnancies, with two surviving to birth. The company that is now offering cloning is made up of some of those same scientists. They predict prices may fall to a bargain $50,000 as they perfect their technique.

Cloning won't get you the exact pet you've lost, because every dog or cat is the product not only of genetics, but also of many random genetic events during development. For example, a clone of a spotted cat won't have spots in the same places as the original because of random timing of cell divisions carrying different color hairs. A clone will also differ because of environmental factors such as experiences and nutrition.

Cloning presents a problem in the world of breeding and competition. No dog or cat registry will register cloned animals at this time. Most breeders feel that cloning runs contrary to the objectives of improving a breed because it simply produces genetic replicas of existing animals. Even if such dogs or cats are outstanding breed representatives, making more of them risks reducing a breed's gene pool. So perhaps it's no surprise that the first dog owner to spend $150,000 for a clone has not earmarked that money for a Westminster Best in Show winner with a fancy name, but for a beloved and much-missed pet pit bull who simply goes by Booger.

Why Dogs Are So Hard to Clone: To clone a mammal, scientists start with harvested mature eggs. But because dogs only ovulate twice a year, and scientists haven't found a way to induce canine ovulation, eggs can be hard to come by. And unlike other mammals, in which eggs mature in the ovaries, dog eggs mature in the oviducts about 72 hours after ovulation. So instead of aspirating eggs fairly easily from the ovaries, they must be surgically removed from the tiny oviduct.

After removal, the eggs' genetic material is replaced with that of the animal to be cloned. The resulting embryos are grown in the laboratory for several days and then implanted into surrogate mothers that have been given hormones to prepare them for pregnancy. But nobody has ever been able to grow dog embryos outside of a dog.

So as soon as the eggs begin to develop into embryos--within four hours of starting the cloning process--they must be surgically placed back into the oviduct. And because no hormones have ever been found that prepare dogs for pregnancy, the eggs must be implanted back into the same dog from which they were just removed.