Hello! I was wondering why x-rays are commonly done on pregnant animals, when they're considered dangerous for pregnant humans?
Loving this question! In general I don’t approve of radiographs on pregnant animals either, and neither does the Orthopedic Foundation for Animals–for the mom, not the puppies. This is because her hormones during this time can cause joint laxity and even luxation during positioning. And you are right, there are risks to exposing the fetus(es) to radiation. But there is one specific time when I do–and just took one yesterday, in fact!
Let’s say for the sake of argument that you have a Chihuahua that was bred about a month and a half ago–she’s at the 48 day mark, in fact! Well, around day 45 the skeletons of the pups inside her have begun to ossify. Prior to that they were cartilage models, present but utterly moot when it comes to taking radiographs because they blend in with the other soft tissues in mom’s abdomen. Day 50 is when they should be at their strongest, so I like to try and wait until then until radiographing.
Now, a Chihuahua is a tiiiiiiny dog. Her puppies surely can’t get so big they’d cause a problem, right? Wrong. If the breeding only resulted in one puppy (and
sometimes often does), that puppy doesn’t compete for any nutrition or room in the mother’s abdomen. She still swells up because the puppy grows so big! So in Chihuahuas (or small breeds in general, or breeds with big heads, like Bulldogs (who don’t even whelp naturally in most cases but that’s another rant for another time)) it’s important to know if there’s only one puppy in there, or several. We can measure the widest diameter of their skull against the most narrow point of the mother’s pelvis to make sure the skull can even fit through the pelvis. If it can’t, the pup would get locked in place during a natural delivery, forcing an emergency c-section rather than a much calmer planned one where mom isn’t already stressed from trying to deliver the puppy and exhausted from failing to do so.
That’s really true of any breed, but more obvious in our tiny or otherwise weird looking ones. So why, yesterday, did I take a radiograph of a Goldendoodle?
Still for the puppy count, but for planning reasons. Without radiographs, if mom had stopped whelping after puppy nine at home, how do you know there isn’t a tenth puppy? With a radiograph, we can give a reasonably accurate head (or spine) count so that if mom stops whelping (and isn’t just taking a break) we know that something’s going on. Maybe the next puppy is stuck, maybe the next puppy is dead or even mummified, maybe she strained so hard to push the last puppy out that she ruptured her uterus and now the other puppies are actually IN her abdomen. It’s basically a way to know for sure that everyone is out. In humans, ultrasonography is pretty good at doing a head count and actually identifying problems with babies. And before the skeletons come around, we veterinarians can use the ultrasound to diagnose a pregnancy and to check fetal heart rates, which can indicate stress. But it’s really sucky at doing head counts. There isn’t as much of a “window” around the fetuses to differentiate them from the abdomen or each other (less amniotic fluid, that is), especially late in the pregnancy. And that’s why we go with the radiographs.