The Hidden Dogs of Dog Cloning [View all]

[Cattledog]

It takes numerous dogs to clone one, raising animal welfare issues

Dog cloning. You’ve probably heard about it. Barbra Streisand certainly has, and she’s not alone. And if we’re being honest with ourselves, who hasn’t looked at a beloved dog and wished for more time? The grief of losing a dog is real and is in no way trivial. But as a dog lover — not just a lover of one particular dog — would you actually want to look into cloning?

Cloning is pretty much what your 9-year-old self thought: it replicates an individual’s genetic makeup, and tada(!), out comes a genetic clone. It sure seems like a straightforward, one-to-one process — take cells from a beloved dog, send them to a cloning lab, and get back your cloned BFF. But the “tada” part is anything but straightforward, and that’s where the animal welfare concerns arise.

In 1996, Dolly the sheep became the first cloned mammal. Since then, cloning took off, sort of. Mice, cows, pigs, goats, rabbits, and cats were relatively easy to clone, but a multi-million-dollar project out of Texas A&M to clone a dog in the late 1990s — the Missyplicity Project— did not produce another Missy. As reported recently in Scientific Reports, “What made dog cloning challenging was certain unique aspects of the reproductive process in canids compared to most other mammals.” Dogs have a more limited breeding period, and it can also be difficult to extract their eggs, a necessary step in the cloning process.

The first cloned puppy, Snuppy, an Afghan hound, was born in 2005 at Seoul National University using somatic cell nuclear transfer (SCNT). In this technique, eggs are removed from female dogs, the nucleus is removed (enucleated), and body cells from the to-be-cloned dog are injected into the eggs. The eggs serve as host for the genetic material of the dog to be cloned. Electric stimulation makes the egg divide, and divide, and divide to behave like a growing embryo, and eggs are then implanted into a dog who serves as a surrogate. The history of dog cloning shows common use of multiple surrogates.

The protagonist of the dog cloning story is not the cells to be cloned or even the cloned dog. Instead, the unseen protagonists are the dogs behind the scenes giving one dog’s cells a new run at life. Cloning research — and the cloning of any beloved pet dog — relies heavily on female dogs. Not only for their eggs, but also as surrogates to birth the clones. In the cloning business, these dogs are housed for the purpose of egg extraction and implantation, with varying success rates.

To produce Snuppy, the first dog clone, over 1,000 embryos were surgically transferred to 123 surrogates, resulting in three pregnancies. Out of those three, one fetus miscarried, and two were carried to term — one clone had neonatal respiratory distress and died within three weeks, and the other became the world famous Snuppy. A 2008 paper described the cloning of a toy poodle by implanting 20 dogs — two became pregnant, and only one maintained the pregnancy to produce a live puppy by caesarean section. Of course, many more dogs were part of the early stages to figure out the just-so technique needed to clone a dog.

Entire article at:

https://blogs.scientificamerican.com/dog-spies/the-hidden-dogs-of-dog-cloning/?utm_source=twitter&utm_medium=social&utm_campaign=sa-editorial-social&utm_content=link-post&utm_term=biology_blog_text_free&sf183794341=1