Research on Equine Pregnancy

Pregnant white mare running in pasture.
Pregnant white mare running in pasture. Anastasija Popova

Newsdate: Thursday, June 23, 2022 - 11:35 am
Location: GUELPH, Ontario

The value of long-term studies is well understood by researcher, Dr. Keith Betteridge who has been involved with Ontario Veterinary College equine reproduction studies since 1986.

Veterinarian caring for newly born foal.

Veterinarian caring for newly born foal

Pregnancy was always looked at as though the embryo was just a passenger in the mare's uterus,but it has gradually emerged that the embryo is a very active participant in pregnancy.
© 2007 by Barb Cypris New window.

Since graduating as a veterinarian from Bristol University, England, in 1959, Betteridge has seen reproduction technology evolve with the introduction of ultrasound in the 1980s and, most recently, RNA sequencing which has been utilized to better understand how the equine embryo develops.

It is amazing that samples from embryonic losses in early studies (2008) are proving useful in studies decades later (2021).  “Long-term studies gave us an opportunity to really follow those embryos,” says Betteridge.  “The ‘lemons’ from the lost pregnancies in early studies turned into lemonade as new techniques came along which we could use to further investigate those samples.”

In a fascinating video interview Betteridge takes you on a journey through studies on equine reproduction.  He also describes how the equine embryo is truly unique with its unusual coating (called a capsule) which allows the embryo to move around in the uterus.  

With ultrasound, an embryo can be detected as early as 9 days in. Betteridge explains that approximately 17% of equine pregnancies fail and 70% of those losses will occur in the first six weeks of pregnancy.

“Pregnancy was always looked at as though the embryo was just a passenger in the uterus,” explains Betteridge.  “It has gradually emerged since the 1960’s that the embryo is a very active participant in pregnancy. If the embryo is not communicating with the mare, the pregnancy won’t develop."

"Understanding the two sides of the conversation between the embryo and the mare is absolutely vital to understanding how pregnancy will develop normally and how, when an embryo is lost, the pregnancy will fail.” 

RNA sequencing has provided new methods of finding out which genes are active in the lining of the uterus at a particular time.  The ‘dialogue’ from the mare’s side has been examined and future studies will hopefully reveal the ‘conversation’ from the embryonic side.

With continued research we are gradually building up information that will help the horse breeder reduce the number of pregnancies that are lost.

Interested in learning more about reproduction? Sign up for Equine Guelph’s fall online 12-week course Management of the Broodmare, Stallion and Foal.

Equine Guelph is the horse owners’ and care givers’ Centre at the University of Guelph in Canada. It is a unique partnership dedicated to the health and well-being of horses, supported and overseen by equine industry groups. Equine Guelph is the epicentre for academia, industry and government – for the good of the equine industry as a whole. For further information, visit

 Press release by Equine Guelph - Story by:  Jackie Bellamy-Zions

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