Horse Breeding

Embryo Transfer

Embryo transfer (ET) is a process where a mare is inseminated and about 6 to 8 days later, the embryo is flushed from the uterus and transplanted to a recipient mare. The process was made a viable option by work at Colorado State Veterinary School and is now performed by a number of veterinarians throughout the country.

You should check with you breed registry to assure they will register foals that result from ET. The Dutch Warmblood Studbook in North America (NA/WPN) does recognize the procedure and will register multiple foals in a single year.

Embryo transfer is a technique that is gaining in popularity for a number of reasons:

• You can keep your mare in full training.
• You have the possibility of recovering more than one egg.
• You may breed your mare more than once per year.
• You may obtain an embryo, have it frozen for shipment or later transplant.
• It eliminates all possibility (as with any other AI) of injury to the mare during breeding.

The procedure works like this:

1. The mare is inseminated.
2. Six to eight days after ovulation, the fertilized egg (s) are collected by inserting a catheter into the uterus through the cervix.
3. The quality of the egg(s) recovered are then graded.
4. A fertilized egg is implanted into a recipient mare.  The two methods of implanting the egg are by surgically inserting into the uterine horn or by transcervical insertion using a pipette or specially designed insertion device.