Why Are Cows Not Put Under General Anesthesia for Surgery?

So as we were digesting the mountains of turkey, mashed potatoes, pumpkin pie and other goodies after Thanksgiving dinner last week, I was talking with some family about cattle things. One question that was asked was why cows usually do not go “under” like people do when we are doing surgery on them. Like most things, there’s a few good reasons for that, most of which wouldn’t be intuitive.

Carolyn gloving in with a creepy smile

Just like it may not be intuitive that this look is actually non-threatening, despite the fact it still scares the heck out of me. She’s not using this on me, right?!?

The first reason has to due with the size of a cow. Most weigh between 1200 and 1500 pounds. If we put them under general anesthesia to knock them out completely, their size puts so much pressure on the side next to the ground that it inhibits the flow of blood to those regions. If there long enough, it can cause death of those tissues. That’s why in the rare case where a cow does undergo general anesthesia (usually only done in speciality hospitals, like universities) they need to be on a padded bed to alleviate the crushing potential.

“Then why doesn’t this happen when they fall asleep?” you might ask. When they are sleeping, they can position themselves to prevent this and move if they get uncomfortable. That doesn’t happen when they are under anesthesia, as they aren’t awake to move.

The other reason for not using general anesthesia is because the process is intense on cattle. Their lungs are huge, so they require a huge respiration machine to help them breathe. They need a special tilt table as they go under so they don’t fall and hurt themselves. Then they need a safe recovery area so they don’t fall and hurt themselves while “drunk” from the anesthesia. In emergency procedures when time is of the essence, this process is not expedient.

Carolyn scrubbing the calf for surgery

This is contrasted to doing surgery while awake and standing, which just requires normal restraint. 

This doesn’t mean that anesthesia isn’t used in surgery. Rather, regional anesthesia, also known as a local block, is the main form used. If you’ve ever had a wart or mole removed when you are awake, the stuff that is injected in your arm to numb the area is what we use on cows. This means that once the area is numb, the cows may feel some pressure from the surgery on the un-numbed areas, but they do not sense any pain or feeling in the areas where the surgery is occurring.

This lack of feeling holds true even for surgeries that are inside the abdomen, like a C-section. Cows won’t have the same sensations on internal structures (such as her uterus) like they do on external structures (like skin). So regional anesthesia works well even with intra-abdominal procedures.

Most cows will stand just fine for surgery, however, some can be a bit unruly. Rather than let her bounce around and possibly contaminate her surgical site, we can give her a little tranquilizer to calm her down. With a mild dose, she stands still and the surgery can proceed, the problem can be fixed, and that cow can go back to frolicking in the pasture.

-Jake

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