VET VIBES
Embryo transfer
the embryo, along with a small amount of the flushing fluid, is inserted into her uterine horn. All procedures are performed through the cervix of both the donor and the recipient mare with no invasive surgery involved. In order for the procedures to
Is embryo transfer the right choice for your mare? DR DOUG ENGLISH looks at some of the basics.
be carried out efficiently and safely, a good, protected crush area is essential.
Frozen embryos An embryo can be frozen to be inserted into the recipient mare at a later time. Such embryos can be transported long distances, thus removing the necessity for the recipient mare to be in the same location as the donor mare. Ideally, a frozen embryo should be around six days old, and the recipient mare needs to be at about the same stage in her ovulatory cycle (i.e. six days) or a few days later, when the embryo is implanted.
Success rate Aside from any other consideration, in order for a healthy embryo to be recovered the donor mare must of course be fertile, and the stallion must have proven fertility in the breeding modality (e.g. live cover, artificial insemination) that has been chosen. When fertile mares and stallions are used, a viable embryo is recovered approximately seventy per cent of the time.
Synchronisation If a freshly harvested embryo (rather than one that has been frozen) is being used, close attention to detail is critical in all stages of the process. Both mares must be synchronised in their oestrus cycles to ovulate at about the same time or within a few days of each other. In the recipient mare, ovulation is best a day or
T
so later. While the donor mare should be as healthy as possible, it’s more critical
he first transfer of an equine
The flushing fluid is collected and
to make a discerning choice regarding
embryo occurred in 1974.
closely examined in a laboratory set
the recipient mare, whose health should
Embryo transfer in equines is
up beside the crush, not just to find
be excellent. The size of the recipient mare is also important. She should be
seemingly simple and involves flushing
the embryo but also to determine its
a fertilised embryo from the donor mare
viability. Seven or eight days later, the
and stallion. A recipient mare should
while she is safely held in a crush.
recipient mare is put into the crush and
have had a previously healthy foal or
32 | E Q U E S T R I A N H U B I S S U E 8 • 2 0 2 2
equal to, or bigger than the donor mare
