Making the switch to embryo transfer...good idea or not?

The advent of treatments such as in vitro fertilisation (IVF) and embryo transfer have helped many people to get pregnant in cases where a natural conception was not an option. The egg is fertilised outside the body in IVF, i.e. in vitro, whereas embryos are transferred back into the uterus in embryo transfer.

However, within the veterinary species embryo transfer is also an important method in which to help achieve pregnancy. Embryo transfer in farm animals consists of embryos being taken from one individual and being transferred to another until the completion of pregnancy. This method might be important when the animal in question is unable to conceive naturally, to prevent genetic traits being passed on to offspring that would not be advantageous or alternatively, to ensure the birth of offspring with particular characteristics (Merck Veterinary Manual). Embryo transfer therefore allows a certain degree of control when trying to acheive pregnancy.

In horses and cattle, embryo transfer has high success rates (50% - over 90% and 56.1% - 77.1% respectively, Allen WR, 2005 and Hasler JF, 2001). Consequently, it is easy to appreciate why embryo transfer is carried out in veterinary species, which is made even easier due to the ever more sophisticated veterinary ultrasound technology currently available.

It should be mentioned however that embryo transfer is more expensive and requires more skill than setting up either a natural pregnancy or breeding programmes, and these factors should be taken into consideration. Of course, the ethical implications of such a treatment should also be deliberated - is trying to create the 'perfect offspring' acceptable? And if so, is this something that is likely to be easily achieved?

In sum, despite the clear advantages of carrying out embryo transfer on veterinary species, the disadvantages should also be examined to make sure the correct decision is ultimately made.

This article was written by Dr Melissa Fletcher, science writer (Vet Image Solutions).