Warning: This post discusses medical procedures on dead dogs. Neither aspect of that sentence is very pretty, so if you're squeamish, or sensitive about animals, proceed with caution.
As the title suggests, this week has been heaps of fun. Starting tuesday morning, we got our cadavres, and had three packed-full days to get as much out of them as possible. We cut, stabbed, tied, dissected, and tubed every single part of their little bodies.
The dogs come from a nearby shelter, usually a variable amount less than ten, and the roster is kept small so that there can be two students to a dog. In first year, it was five students to a dog, and in fourth year it was groups of three for surgery lab, so this is a huge opportunity. Somewhat distressingly, the shelter purportedly never has an issue with supplying enough dogs, and the animals are not withheld at the shelter for more than a day. Most of the animals are pit-bull crosses, so I think there's an unfortunate excess of unwanted, potentially dangerous young animals in the area. Anyway, we had 8 dogs for 15 students, and when they first arrived we had to be speedy to take advantage of certain things before rigor mortis set in.
First thing we had to do was put a little bottle in their mouths to keep their jaws open. Believe it or not, it's very difficult to later do stomach tubing if their jaw is locked closed. The next step was to jump to the procedures that involved fluids: blood, joint fluid, CSF, and bone marrow. For every procedure, the vets gave a demonstration, and we went off and performed it on our own dogs. Here are some of the highlights.
CSF tap: To obtain cerebrospimal fluid, you stick a needle in between the vertebrae into the space around the spinal cord. You can do this right behind the skull, or in the lower back. After you feel your bony landmarks, you basically just go for it, and pop the needle in. Unless you are awesome(*), it likely will hit one of the bones on either side and needs to be redirected--and let me tell you, the feel of a needle crunching against bone is horrible. When you get it into the joint space, it goes all the way in, nice and smooth. When you don't, it smacks into bone early and won't move, so you have to poke, redirect, poke, and redirect until you get it, with an awful scraping sensation against the not-quite-solid surface.
*I got the lumbosacral cistern on the first try. That one has a slower flow in general, and also our dogs are dead, so I wasn't sure at first. But I didn't want to give up on it, so I waited, and 30 seconds later came the satisfying clear goop oozing out of the hub of my needle.
Bone marrow aspirate: Take what I was saying about bone before, now imagine a giant metal stick with a handle that you shove forcibly down a shoulder into the humerus. Surprisingly good for getting out stress, as you crank that handle back and forth like you're grinding your fist into your worst enemy's face. If you get a little too into it, your marrow aspirate turns into a core biopsy, because you punch through the cortex and get a full piece of bone, rather than sucking up the viscous marrow. There is actually a difference in what they tell you diagnostically.
Chest tube: This one is both terrifying and hilarious, as your big, thick chest tube goes onto a similarly big, thick metal stylette with a pointy end. You grab the bottom about a centimeter up from the pointy end, to avoid skewering the patient, and with your other arm you bang it through the chest wall with one swift smack. Pop! Pointy end into the patient, and your fist stops you from stabbing the heart or something.
Another fun aspect is that you need to make a tunnel under the skin so you don't accidentally let a bunch of air into the chest. This means an assistant grabs fistfulls of dog fur and holds them to the side, so that once the chest tube is in, when they let go the loose skin will fall back into place and make it so the entry point in the skin was several rib spaces farther down than the point through the body wall. When you're all done, you can really see the tube there, right under the skin, a smooth squishy cylinder. You secure the tube in place by what is known as the Chinese finger trap suture, not even kidding.
Oesophagostomy: Since we had the foresight to prop open our dog's mouth, we were able to attempt stomach tubes. There are a few methods, like through the nose or through the oesophagus. The latter is useful because it can be a semi-permanent way to bypass the mouth or provide/force nutrition easily. The way it works is you make a cut on their neck, into the oesophagus, and stick the tube in from the outside. You have to fiddle around, grabbing the tube from the inside and fussing with it until it's in the direction you need, and apparently this is next to impossible in a dead dog. But because, as we've already established, I am awesome, I totally got ours into place.
Exploratory laparotomy and experimental surgery: Towards the end of the first day, we had to gut the dogs so they wouldn't become too smelly and horrid over the week. But there's no sense in just gutting them, so we explored their abdomens first. We checked out all the organs, took biopsies of everything (which involve a number of bizarre stabby instruments), did pretend surgery on the intestines, and generally poked, prodded, and sliced anything we could get our hands on. The pretend intestine surgery is fun, because you cut out a piece, tie it back together, then turn it into a water balloon to see if your seal was water-tight--that is, hold it off and inject it with water. We even castrated our dead dog, and put in a urinary catheter such that we could see when it got to the bladder.
"If you get bored": As if we didn't have enough to do, they had tons of extra equipment to make extra sure we didn't run into any down time. There were otoscopes, slides for looking at our samples, nail clippers, syringe and needles for lymph node aspirates, you name it. Unfortunately, because our dogs arrived an hour later than they were supposed to, we ended up quite tight for time.
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