File this under: cool vet procedures
I’m doing two weeks of EMS at a dairy farm right now, which has been pretty decent so far. The dairy is owned by the vet school and is therefore closely affiliated with the hospital, so this afternoon a vet came out to ‘borrow’ some blood from a cow for a blood transfusion.
My friend and I were allowed to watch the procedure, which was very, very simple. I was under the impression that something as complicated as a blood transfusion would not be attempted on a farm animal, due to cost and risk. Actually, I was completely wrong: the procedure isn’t very complicated at all (although perhaps a bit daring) and used only simple tools, so that a vet would mostly charge the farmer for their time. All she used was: a large bucket, some sodium citrate as an anti-coagulant, a local anaesthetic, a few plastic screw-top containers, a scalpel, gauze, and some suture material. And a cow! Regardless of their simplicity, blood transfusions remain uncommon, mostly because, as you’ll see, you gotta have some guts to try it.
First, after the cow was secure in the crush, the vet raised the jugular vein using pressure from a piece of string and some gauze. She gave the anaesthetic, clipped the hair, poured a bit of alcohol, and then sliced a large hole into the vein. The blood flowed directly out of the vein and was caught by the bucket, where it was whisked together with the anticoagulant. We collected about a litre, which isn’t very much, considering that most dairy cows have about 60 litres in them! Pressure was removed and blood flow slowed down considerably, and the vet sutured up the cut. There is a small risk of infection, but cows are notoriously hardy animals and she should heal smoothly.
Next, we poured the blood into the small screw-top containers. Normally, a bag would be used, but since the blood was being transported by car to the hospital, containers were a safer method. We scrubbed up, then the vet asked my friend and I to go with her to the hospital to help with the actual transfusion.
The most common reason for a blood transfusion in a cow would be during birth, when blood loss by a vaginal artery might be fatal. Usually the artery can be cauterised, but heavy blood loss may require a transfusion. We were delivering this blood to a calf, because he was haemorrhaging internally due to a disorder affecting production of blood cells involved in blood clotting. The vet explained that the cause of this disease was unknown and under investigation, and so far the only known successful method of recovery was blood transfusion, which restores some number of clotting factors.
(Just in case you were wondering, bovines also have blood types. However, unlike with humans, they don’t produce antibodies against foreign blood types until after exposure. So, this calf could receive a single transfusion, but next time he would need to be blood-typed, and receive blood from an appropriate donor.)
The calf, while lively, had blood coming from its nose, and was breathing heavily - because of decreased red blood cell levels and therefore decreased ability to provide adequate oxygen for tissues. Upon post-mortem exam, calves with these symptoms often show heavy internal bruising, so we had to be firm in handling him so that he would stay still, but also needed to avoid accidentally giving him any knocks ourselves! We placed a catheter in his neck, sutured it so that it wouldn’t fall out easily, attached him to a drip line of a bag full of the collected blood, and let the little man go.
So far, only one calf has survived this disease, and while the calf we saw was alert, the vet said already his condition was deteriorating from the morning. Prognosis wasn’t good at all, but at least he was given a chance.
For my friend and I, it was nice to get a litte reminder of why we must keep shoveling cow poop: because someday we’ll be the ones collecting and transfusing blood. Well, maybe….