In vitro fertilization (IVF) has been successful in people for many years. This assisted reproduction technique involves harvesting eggs from a female and fertilizing them with sperm in a petri dish. They are then incubated carefully until scientists are sure that an embryo is developing. The embryo is then implanted into the fallopian tube of the original or surrogate mom; if all goes well, it then develops into a fully formed baby. It all sounds straightforward, but when it comes to dogs, it hasn't been that easy. Scientists have been trying to produce puppies using IVF since the 1970's, but until now, they just haven't got it right.
Test Tube Puppies
The first problem that they encountered was being able to collect eggs from a bitch at the right stage of maturity. They tried taking eggs that were at the same stage as other species that had successfully reproduced using IVF but the dog eggs didn't fertilize. With much experimentation, they found that if they collected the eggs just one day later, their fertilization rate was significantly improved. It seems that canine eggs need that extra day in the oviduct.
The next problem was that in the bitch, the environment in the reproductive tract is important for fertilization. That environment needed to be reproduced correctly in the laboratory, and again after some work, the scientists discovered that the missing ingredient in the chemical bath they were using was magnesium; it is essential for sperm cells to be able to swim and penetrate the egg.
The result of this research has been that scientists at Cornell University in New York have successfully produced seven puppies from two mothers using IVF techniques.
A number of developments can come from this discovery.
- Bitches come on heat once or twice yearly. If they are mated and fail to conceive, their pet parent has to wait quite a long time to try again. With this technology, it's possible to implant embryos and improve the chance of a successful pregnancy. This would be useful in the case of a bitch with valuable traits that hasn't been successful in conceiving or in a rare breed of dog where a litter is essential to perpetuate the breed.
- IVF may be used to remove common canine genetic diseases from the gene pool. At the embryo stage, it's possible to remove parts of the genome using gene-splicing techniques. This means that a dog that may have been predisposed to a genetic disease could have that risk eliminated.
- Dogs share a number of diseases with us that have a similar genetic basis. By learning about the genetic diseases in dogs, and working out how to remove them in the embryo, it can help to eliminate the disease in people, too.
In vitro fertilization in dogs will be a costly procedure so it's not going to be an option for the vast majority of breeders. There are also ethical considerations to keep in mind. However, it's exciting to think that as the technique develops, it can have a positive outcome on the health of both people and dogs.
Photo ©Cornell University College of Veterinary Medicine
