why cant horses have twins ?

[Megibo]

i've been curious about the reason-and also noted that there have been alot of twins this year (it seems) and most mares seem to be doing okay.
Is just uterus space, dangerous for the mare, mortality rate, wears down the mare to have two foals etc ?
Just wondering really (although I wouldn't want two foals in one go either!)

 

[eventrider23]

In a nutshell, essentially whilst horses are CAPABLE of carrying twins seeing as they have two uterine horns for the foetus to grow in, however when it comes time for birth, both tend to go into labour at same time....unlike people where one is born after the other...in horses, they sometimes fight for foaling position, causing foaling problems and often death in the mare. In addition, nutrition wise the mare tends to only supply enough food for one foal and so when split between two, one or both ends up weak coupled with the space factors of a mare carrying 2 foals in a very cramped space which in itself can cause problems prior to foaling.

 

[Megibo]

In a nutshell, essentially whilst horses are CAPABLE of carrying twins seeing as they have two uterine horns for the foetus to grow in, however when it comes time for birth, both tend to go into labour at same time....unlike people where one is born after the other...in horses, they sometimes fight for foaling position, causing foaling problems and often death in the mare. In addition, nutrition wise the mare tends to only supply enough food for one foal and so when split between two, one or both ends up weak coupled with the space factors of a mare carrying 2 foals in a very cramped space which in itself can cause problems prior to foaling.

Ahh, okay; thanks

 

[AJBliss]

The placenta in horses is also not very efficient, and normally lines the entire uterus in order to support the growing foetus. In twins, you would have two placentas, each with access to a much smaller area of the uterus, as well as an area butted up against the other twin's placenta that is not in contact with the uterus at all. The contact between uterus and placenta is how the foetus is nourished and wastes removed, so reducing the amount of contact reduces what can be supported. Hope that makes sense!

 

[Megibo]

The placenta in horses is also not very efficient, and normally lines the entire uterus in order to support the growing foetus. In twins, you would have two placentas, each with access to a much smaller area of the uterus, as well as an area butted up against the other twin's placenta that is not in contact with the uterus at all. The contact between uterus and placenta is how the foetus is nourished and wastes removed, so reducing the amount of contact reduces what can be supported. Hope that makes sense!

..in a way..

 

[AJBliss]

LOL, I blame my human baby for my incoherency! Here's a better explanation of the placenta stuff: http://www.thehorse.com/ViewArticle.aspx?ID=12422&src=topic

 

[Megibo]

LOL, I blame my human baby for my incoherency! Here's a better explanation of the placenta stuff: http://www.thehorse.com/ViewArticle.aspx?ID=12422&src=topic

oo ok

 

[tristar]

because the placentas of twins don't have enough nourishment from the mare and one often ends up dying, which through the subsequent infection caused by decompostion makes the mare expulse the both usually.

and because the uterus has a problem nourishing twin foetus, if they are born alive this explains why one is often so much smaller than the other.

thus vets scan and ecrase one twin in the hope the other will continue to full term, because if left to develop they will jepardises the survival of both and even if one is bigger it has a struggle very often to survive