The "twin crush"

The topic of today's therio lab was detection of pregnancy in dogs, cattle, and horses. (Or let's be more specific: bitches, cows, and mares.)

Turns out that if you are ultrasounding a mare in very early gestation (like within a couple weeks of conception), and you detect the presence of twins, that is a big "uh oh" for one of those itty bitty twin horsies.

If a mare tries to carry twins to term, she will very often end up aborting both fetuses around 5 months of gestation (normal gestation is ~340 days).

So the solution, if you detect the twins early enough, is to "get rid" of one of them.

The technique is a little barbaric, I think. You are doing your ultrasound (which is done with the ultrasound probe and your arm in the mare's rectum). You make sure that the "keeper twin" is far away from the "uh oh twin" (they can migrate around the uterus), and then you take your ultrasound probe and physically crush the "uh oh twin" embryo against the bone of the pelvis.

Poof! No more twins!

My therio instructor prefers to call this "twin reduction" rather than the more common colloquial terms of "twin crush" or "twin pinch."

Yet another example of why (a) I don't want to work with large animals, and (b) you should spay and neuter everything.