Monday, February 28, 2011

Equine Twins

Unlike many other species, multiple births or twins are not desirable in horses. Because a mare's uterus is not designed to carry twins, when a mare becomes pregnant with twins, she will either undergo early embryonic death of both embryos before 60 days of gestation or carry them to 7-8 months and then abort the fetuses. Rarely does a mare carry and delivery full term twins. If they do give birth to twins, the foals are usually either dead or very weak and die within 3-4 days. Birthing complications and retained placentas are much more common when mares abort or give birth to twins. There are cases of healthy equine twins being born, but these cases are rare.

This is a picture of our equine reproductive ultrasound. We have two of these units at the clinic. We use these both in the clinic and on the farm to examine a mare's reproductive tract.

Before the advent of the ultrasound in equine medicine, the number of mares producing twins was unknown since they will normally loose these pregnancies early in gestation. Now, with an ultrasound, we can diagnose pregnancy in a mare as early as 14 days after ovulation. Because of this, we can diagnose twins very early in the pregnancy. If twins are picked up on an ultrasonic scan, one embryo can be manually crushed or eliminated. This allows the other embryo to grow and develop normally. This procedure must be performed early in the pregnancy.....before 18 days is ideal. And, the procedure should be performed by an experienced veterinarian. Because we deal with many draft mares and draft type crosses, we commonly pick up twins on the ultrasound. We have become very proficient at successfully reducing twin or even triplet pregnancies to a single pregnancy. We usually see 2-3 mare each season with triplets.
Below is a picture of a sonogram on a Belgian mare, performed by Dr. Scott Nebergall, of a mare who actually had quintuplets....yes, that means 5 embryos! This picture only shows three of them (black circles)....I could not get all 5 on the screen at the same time. This is a record for us at the Arthur Veterinary Clinic.

1 comment:

  1. Fascinating stuff...and now that you mention it, I'd never heard of mares having twins.