First Ever 'Test Tube' Puppies Born with In Vitro Fertilization

First the first time ever, a litter of puppies was born by in vitro fertilization. These "test tube" puppies open the door for preserving endangered canid species using assisted reproduction techniques. It could also allow researchers to eliminate heritable diseases in dogs.

In this latest effort, 19 embryos were transferred to the host female dog, who gave birth to seven healthy puppies. Two were from a beagle mother and a cocker spaniel father, and five were from two pairings of beagle fathers and mothers.

"Since the mid-1970s, people have been trying to do this in a dog and have been unsuccessful," said Alex Travis, one of the researchers, in a news release. Now, it seems the researchers have finally made this possible.

For successful in vitro fertilization, researchers must fertilize a mature egg with a sperm in a lab to produce an embryo. Then, the scientists need to return the embryo into a host female at the right time in her reproductive cycle.

The first challenge was to collect mature eggs from the female oviduct. The researchers first tried to use eggs that were in the same stage of cell maturation as other animals, but since dogs' reproductive cycles differ from other mammals, those eggs failed to fertilize. Through experimentation, researchers found that if they left the egg in the oviduct one more day, the eggs reached a stage where fertilization was greatly improved.

The second challenge was that the female tract prepares sperm for fertilization. This required researchers to simulate those conditions in the lab. By adding magnesium to the cell cultures, the researchers managed it.

The findings have wide implications for wildlife conservation since now researchers can freeze and bank sperm and use it for artificial insemination. The scientists can also freeze oocytes and conserve the genetics of endangered species.

The findings are published in the journal PLOS One.

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