A surrogate dog has given birth to the world's first test tube puppies, American scientists say.
The in-vitro fertilisation (IVF) advance paves the way for conserving endangered breeds and could help in the fight against human and animal diseases, Cornell University researchers said.
The seven beagle and cross-bred beagle-cocker spaniel puppies were born to a surrogate mother.
They were all from the same litter but have three sets of parents.
The puppies were born in June, but their existence was kept secret until the findings were formally published to the scientific world this week.
Frozen embryos were implanted in a female dog using techniques similar to those used in human fertility clinics.
Problems with freezing embryos had caused difficulties in the past, but the group said they had perfected the technique.
"We have seven normal, happy, healthy puppies," Cornell College of Veterinary Medicine lead researcher Dr Alex Travis said.
"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," he said.
The researchers said IVF was a powerful tool to help endangered species of dog.
It could also be used in the study of inherited human and dog diseases. Dogs share many diseases with humans - almost twice as many as for any other species.