Researchers in the U.S. have created the world's first litter of puppies through in vitro fertilization (IVF), a breakthrough they say could help eradicate diseases in dogs -- and in humans.
Seven puppies were born in July from 19 embryos implanted into a host female dog, according to scientists from Cornell University and the Smithsonian Institution.
"Since the mid-1970s, people have been trying to do [IVF] in a dog and have been unsuccessful," co-author Alex Travis, associate professor of reproductive biology at the Baker Institute for Animal Health in Cornell's College of Veterinary Medicine said in a statement.
Past attempts have failed because dogs have different reproductive systems to most mammals.
The researchers found that if canine eggs were left just one extra day in the oviduct they had a much better chance of being fertilized. And when magnesium was added to the cell culture, it helped mimic conditions inside the female canine reproductive tract, which unlike many other animals helps to prepare the egg for sperm.
"We made those two changes, and now we achieve success in fertilization rates at 80 to 90%," Travis said.
An extra challenge was the small window in which to implant the embryo during the dogs' reproductive cycle. The embryos had to be frozen while the researchers waited for the right moment, which only happens once or twice a year.
What happens next?
The pups, healthy and now five months old were bred from a combination of pairings. Two of the puppies are from a beagle mother and a cocker spaniel father, and the other five were from two sets of beagle fathers and mothers.
The techniques used to create the pups are vital for progress in saving endangered dogs, curing diseases prevalent in certain breeds of dogs, and researching cures for human conditions.
Dogs share more than 350 similar heritable disorders and traits with humans -- almost twice the number as any other species -- according to the study, published in the journal Public Library of Science ONE, meaning that the research could be invaluable in furthering our understanding of human ailments.
The simple ability to breed dogs via IVF could help save endangered species, including the African painted dog, otherwise known as the African wild dog. As few as 3,000 are believed to exist in the wild, in parts of south Africa and the southern part of East Africa.
And the opportunity to work with genes could help find more common breeds, for example, golden retrievers, who suffer a higher incidence of lymphoma than most other dogs.
Louise Brown Oldham, the first human born by IVF -- or so-called "test tube baby" -- was born in 1978. Since then the practice has become widespread for couples who have difficulty conceiving naturally.