Fetal sexing of a bull
The last in the series of ultrasound posts was an intro to fetal sexing for bull calves. Here is a video showing what that looks like in real time.
In veterinary medicine, it is important to be consistent, so we work at doing things the same way every time. For fetal sexing, the key is to identify landmarks and move the ultrasound probe slowly to scan the region behind the umbilical cord (bull) and the region under the tail (heifer) for the genital tubercle.
To orient you, the head is to the right and the video sweeps to the left, showing the front legs, the trunk, and the umbilical cord.
To make it easier to identify, the video will freeze for a few seconds and an arrow will briefly identify the genital tubercle. It shows up as a bright white structure and you can watch it as it disappears and reappears in the image during the rest of the video.
We start fetal sexing at 56 days of gestation and this fetus is probably a few days longer than that.
If you've been following the ultrasound videos, the calf that we've been watching grow from a January 1st breeding is now about 50 days old.
The possibility of a spontaneous abortion (miscarriage) never disappears and we expect about a 10% rate of early embryonic death on the short breeding pregnancies we find. Nevertheless, the risk of embryonic death becomes lower as the gestation length increases. So we like to recheck the pregnancies we've diagnosed again after 40 days gestation.
This video shows a fetus with its head down. At the top of the image is a combination of the back legs and rump, and the line jutting off to the left is a front leg. If you look closely at the center of the fetus, you can see the flicker that we were able to identify last week as a fetal heartbeat. An important part of the pregnancy recheck exam is checking the viability of the fetus with a strong heartbeat and making sure that it appears to be growing and developing normally.
We just passed Valentine's Day and what better way to note it than with a heart? More specifically, a calf's heart. In this video, the calf is to the left of the screen and if you look at it closely, you can see a consistent flutter. That is a tiny heart beating. This calf is probably 35-40 days of gestation and the fetal heartbeat is a good indicator of viability.
One of the benefits of ultrasound pregnancy diagnosis is that it makes it easier to detect multiple pregnancies. In most cases that means twins, but we were lucky enough to capture this footage of a triplet pregnancy.
The first two fetuses are laying next to each other in the right horn. Then the video sweeps over to the left horn to the third fetus laying by itself.
I recently heard a triplet pregnancy referred to as a pair and a spare. I guess it fits.
Remember Ebony from a few weeks back? She had a c-section to deliver her calf.
Fetal-maternal disproportion is the most common cause of dystocia in beef cattle. That's a fancy way of saying that most cases of calving difficulty in beef cows happen because the calf is too big to come through the mom's pelvis.
The thing about a c-section is that it's a major abdominal surgery in a barn. So even if the surgery goes well, there is a very real risk of infection and it usually takes a week or so to see if that will be an issue or not.
This video is about 3 weeks post-surgery. The calf's legs have gotten strong and straightened out and he is butting mom's udder because he is hungry. And she looks pretty good too.
Happy calf. Happy cow. Happy producer. Ecstatic veterinarian.
