Some Details on ET

This is a photograph of what would happen most of the day at the clinic, the veterinarian is checking a mare most likely for ovulation or the progress of a follicle. We would do checks like this for pregnancy as well, usually at 7 days after a transfer then again at 14, 21 and 53. The checks are actually recorded as days from ovulation so they would eb 14, 21, 30, 60 and maybe 45.

I would like to discuss the content of two specific sites in this blog. The first is an article from the University of Idaho, Departments of Animal and Veterinary science. The article is written by D.K. Vanderwall and it goes over many of the specific procedures that constitute embryo transfer. The author gives 6 reasons that embryo transfer is useful in the business of broodmares, these I have found are pretty consistent between vet schools and practices. The reasons one would be interested in investing in an embryo transfer would be:
1. To obtain a foal from a mare that was currently performing at a high level
2. To get many foals from any mare (more than one a year)
3. Research purposes
4. Obtaining foals from mares that are two years of age (younger than one would usually breed)
5. Obtaining a foal from a mare that was not reproductively sound
6. Getting a foal from a mare that has other prohibitive health problems such as a tendency to founder

The article contains a brief history of the procedure, stating that the first successful pregnancy as the result of an embryo transfer occurred in 1972, though it was not until the 1980s that the procedure was considered common practice and held validity in the area of veterinary medicine. The next major development was the possibility of storing an embryo in cooled media for several hours. Of course this development allowed facilities to extract embryos and ship them to a location that housed a recipient mare. This makes it possible for the owner of the donor mare to have the procedure done without moving traveling long distances but most importantly they do not have to also keep a recip. mare available and synchronized with the donor.

The part of this article that interests me most is the data that the author sites for the success rates of many veterinarians. The first set of data compares the success rate for embryo recovery dependant on the day post-ovulation that the embryo was collected. The trend increases from 58% with a 6 day embryo all the way to 71% for a 9 day. The data for the 9 day embryos particularly catches my attention since the veterinarian I worked with did not collect any 6 or 9 day embryos. The reasoning for this, as I understand it, is that the likelihood of finding a 6 day is less (as the data shows), but I believe they did not try for 9 days because the embryo would be potentially too large to handle safely or with the most ease.

One final area of interest from this article is the surgical implantation of the embryo. I am not at all familiar with this method, which involves surgical sterilization of the flank followed by making an incision in the flank. Next, the uterine horn is located and a small puncture hole made, the embryo is then deposited into the horn and the uterus is simply pushed back into the mare without any suturing. It was thought (according to Vanderwall) that this method of implantation yielded higher pregnancy rates, though today the non-surgical method (the one I am intimately acquainted with) is just as, if not more successful.

I am planning next to discuss a commercial site which offers some interesting options of creating foals…