Answer: Horses can have twins, but it is rare and typically one or both are lost during pregnancy.
It is extremely rare for horses to conceive twins let alone carry them full term, approximately a 1 in 10,000 chance. Horses can give birth to twins but the mortality rate is high for one or both twins during birth, gestation or shortly after birth. It is best breeding practice to not allow a twin pregnancy to progress to full term.
Why are twin pregnancies bad for horses?
A horse’s uterus is not designed to carry two foetuses, due to the lack of room for the placenta and the possible complications relating to the birth canal in larger animals such as horses and cattle. Unlike animals such as sheep and goats where twins are quite a common occurrence. A mare carrying twins has the increased risk of complications and carry a much higher risk for both the mare and the foals. You have the increased stress of a double labour, putting extra strain on the mare, together with the possibilities of birthing difficulties, this all heightens the risk to the mare during labour and in extreme cases can lead to death.
How to avoid twin pregnancies in horses
Carrying twin foals is considered so high risk that most responsible and experienced breeders will have their mare checked by their veterinarian for twin pregnancies early on. A rectal ultrasound scan is the most common method of checking and is generally considered a routine part of the breeding process. If two embryos are detected, the veterinarian can perform a procedure known as “pinching or squeezing off” essentially terminating one of the pregnancies. They usually choose to keep the larger or strongest looking embryo. By doing this the remaining embryo is given the best chance in allowing it to thrive and increase its chances of being successfully born.