First ever IVF puppies have been born to a surrogate mother after years of attempts, say scientists at Cornell University in New York.
The IVF success paves the way for conserving endangered breeds and could help in the fight against human and animal diseases, say researchers.
The seven beagle and cross-bred beagle-spaniel puppies were born to a surrogate mother.
They were from the same litter but have three sets of parents.
Frozen embryos were implanted in a female dog using techniques similar to those used in human fertility clinics.
Problems with freezing embryos have caused difficulties in the past, but the researchers say they have perfected this and other techniques.
Lead researcher Dr. Alex Travis, from Cornell’s college of veterinary medicine, said: “We have seven normal happy healthy puppies.”
He added: “Since the mid-1970s, people have been trying to do this in a dog and have been unsuccessful.
“Now we can use this technique to conserve the genetics of endangered species.”
The researchers say IVF (in vitro fertilization) is a powerful tool to help endangered species of dog such as the African wild dog.
It could also be used in the study of inherited human and dog diseases.
Dogs share many similar diseases with humans – almost twice as many as for any other species.
Dr. Alex Travis said the work was an important milestone.
The puppies were born on July 10, but their existence was kept secret until the findings were formally announced to the scientific world this week.
They have reportedly been named Ivy, Cannon, Beaker, Buddy, Nelly, Red and Green, and all but one has gone to a new home.
The research, published in the journal PLoS One, has been described as a “major step forward” in medicine.