Turtle Necropsy

A lot of people seemed to be really interested in my previous reptile necropsy post. And hey, I was pretty interested in it too. I was able to have a similar experience recently, but this time we only necropsied red eared sliders. We were supposed to be doing a shell repair lab, but unfortunately we ran out of time for that one. Hopefully sometime in the future I'll be able to actually work on that.

So as I mention, we necropsied red eared sliders for this wet lab. Most of the sliders had been part of a research group, and the cause of death was unknown. That wasn't really why we were originally intending to do this, but that's what we ended up doing.

The major difference between necropsying a turtle and any other reptile is that really hard thing called a shell that gets in your way. We had to saw through the shells on all of the turtles to gain access to the rest of the body cavities. And the muscles on a turtle's legs are actually attached to the shell on the inside, so you can't just saw one side open and then lift it up like your opening a lid. It takes a surprising amount of work. In fact, it took us longer to get the shell off than it did to identify the cause of death.

Opening the shell

Once you're inside, the most obvious difference in turtle is probably the location of the scapulas, or shoulder blades. Whereas ours are on our back on the dorsal surface, in turtles they are the complete opposite. Their shoulder blades are located where our collar bones are. The rest of the organs are pretty easy to distinguish- trachea, esophagus, stomach, intestines, heart, liver, and so one. When we opened up our turtle and started looking around, the first thing we noticed was an abnormally large liver. We did have to ask about that, because I have no idea what the normal size of a liver in a red eared slider is. The liver also had an abscess on it, which looked like a darker, harder area on the liver.  The second thing we noticed was there was a problem with our turtle's heart. Turtles have a three-chambered heart, made up of two atria and one ventricle. (Humans and other mammals have a four-chambered heart made up of two atria and two ventricles.) And our turtle had one atrium that was substantially larger than the other- and this one I knew for sure, because I had something to compare it to. The enlarged atrium also had an abscess on it. You might be able to imagine that that would cause a lot of problems for the poor turtle.

Enlarged liver. You can also see that the scapula are on the ventral surface, where our collar bones would be.

Heart with an atrial abscess. The abscess is the whiter part on the dark red atrium. You can see how much larger it is than the other atrium. 

For the first turtle we just finished by doing essentially an exploration or anything else we could see. Turtles and most reptiles don't have a diaphragm, so they don't have a separate thoracic and abdominal cavity the way that we do. Everything is pretty much all lumped in there. In fact, the left lung sac was actually sitting under the stomach. If that happened to a dog, that would be a pretty big problem. 

We found the tracheal bifurcation and followed it to each lung sac, which is much different from human and other mammalian lungs. In turtles the lungs are attached to the carapace, or the upper portion of their shell. There is no negative pressure in the lungs, so that if the shell is fractured the turtle can still breathe. Also, as a fun fact, turtles can't cough. It's one of the reasons they are so highly susceptible to pneumonia. We also followed the esophagus to the stomach, which was pretty unremarkable, and then to the mass of intestines. The small intestines were actually pretty cool, because they have this ringed pattern to them, which almost makes them look more like worms. 

Pulling out the stomach for better visualization. You can see the small intestines here as well, which look sort of like worms.

Then we moved onto a second turtle, looking for something interesting. The second turtle actually had a shell fracture, right down the middle at the base of the shell, over the tail. She had been paralyzed in the hind limbs, and we wanted to see if she had had either a broken pelvis or some kind of nerve damage. When we opened her up, one big difference jumped out right away, which was that her abdomen was full of eggs. The amount of space dedicated to reproduction in turtles is insane. There were literally eggs everywhere. We opened one up, but all it was inside was a frozen yolk, which was just from freezing the turtle for preservation. Turtle egg shells are surprisingly soft and squishy though. They're like lizard eggs, and this actually really through me off the first time my lizards laid eggs, because I was expecting something much harder. But this turtle also had multiple stages of egg development inside of her, so that was interesting to see. It's always sad doing a necropsy on a pregnant animal, but since she was paralyzed in the hind limbs, I'm sure she would have had a lot of difficultly delivering the eggs, if she even would have been able to. 

Female turtle with her eggs. All of the little yellow round ball things are developing eggs.

We tried to get down to her vertebrae to see if there was nerve damage, but we never were able to get deep enough. I think it's a pretty safe guess that that's what the problem was though. The pelvic nerve plexus in a turtle sits right under where her fracture was. We even removed what we think was the fiberglass over her shell fracture to try and get a better look, but we just couldn't see anything. It did make me more interested in wanting to know about turtle shell repair though, so hopefully we still get that lab! There are a couple of different methods for shell repair that I know about, such as metal bridging, a cable tie method (who knew there was such an awesome use for them!), and using fiberglass and epoxy. I wish I knew more about how to actually use those methods, but hopefully I will be able to have a turtle shell repair blog post in the future.

Removing the fiberglass to expose the shell fracture. This shell fracture was perfectly down the middle of the shell.

And just on a random side note, I had noticed that our first turtle had stitches under her tail, so I asked what they were about. And apparently this turtle had been part of a research group for laser therapy. The turtles all received an incision by the tail, and then half of the group received laser therapy while the other half received only conventional medicine. And that study found that laser therapy significantly sped up the healing process. Pretty cool. 

Stitches

I love all turtles, and I love my tortoise. And I love learning about them and what makes them so unique and different. =]

Assistant Surgeon

Part of our junior surgery class is participating in live spay and neuter surgeries, usually working under 4th year students who are currently taking the shelter medicine rotation. We have to do about 12 surgeries total; 6 as an anesthetist, 3 as an assistant surgeon, and 3 as the primary surgeon. I'm not going to lie, I was pretty nervous. I had my surgeries scheduled before I even finished my cadaver surgeries, and I was not at all confident that one spay would prepare me to be an assistant surgeon. I couldn't even do my neuter, because my dog came already neutered. Not the best situation help with confidence levels.

But I have now completed all three of my assistant surgeon roles in live surgery. And while I had something pretty close to a panic attack before my first one, looking back I really enjoyed them. I learned way more from the live surgeries than I ever could have from the cadaver labs, and my confidence shot way up. Usually my 4th year primary surgeon let me do about a third of the procedure, such as removing one testis, or tying the Miller's Knot around the uterine body and transecting the uterine body. I didn't even learn the Miller's Knot until the live surgeries, even though that's all they use. I also learned how to do an instrument tie, although I'm not quite as proficient at that yet. I'll need to practice that.

With every surgery, I always feel like the beginning is just a huge mass of confusion. The anesthetists are trying to figure out what instruments need to be gathered for the catheter and endotracheal tube placement, the assistant surgeons are gathering gowns and surgery packs and gloves for the actual surgery, and I have no idea what the primary surgeons are getting ready. The beginning always feels like no one knows exactly what we should be doing. But then once we move to actually operate, I feel like everything always calms down. Anesthesia is all hooked up and only has to monitor, and the surgeons just kind of do their thing. And occasionally there is some excitement if the anesthesia gets a little light- usually it took took too long to actually begin the surgery and the anesthetic shot we give in induction is wearing off- but that has been the only wrench I've encountered so far. Knock on wood.

For the assistant surgeon role, the main job is obviously to assist the primary surgeon. This means that I would be responsible for doing the physical exams on the patients first, to make sure they are actually healthy enough for surgery. Then some of the patients get different shots with us too- some get rabies, some get distemper, some even get microchipped. I get to do all of that, and record where they shots were give to watch for an injection site reaction. Then after the patient has been induced and intubated by anesthesia, I prep the surgery site. So I clip the hair and perform a primary sterile scrub with chlorhexidine. Once the patient has been moved onto the operating table, I do a secondary sterile scrub. Then I go scrub in while the primary surgeon drapes the patient.

During the surgery, the only guidelines are to do whatever the primary surgeon asks for. Usually this involves handing over instruments, holding things out of the way such as mosquito clamps holding tissue, or helping keep suture tight. As I mentioned earlier, if the surgery is going well and appears to be uncomplicated, I have also been able to perform actual pieces of the surgery. On my second surgery as assistant surgeon I exteriorized a testis, stripped down all the spermatic fascia, clamped, sutured, and cut the spermatic cord. I learned so much more from doing this one testis than I did from anything in the cadaver lab. It may seem obvious, but dead animals don't bleed, and live animals bleed a lot. So you don't get that experience of looking and checking for hemorrhage and looking for structures through blood until you actually do a live surgery. The experience is really invaluable.

Then after the surgery, the people responsible for anesthesia stay with the patients until they wake up. You have to watch for the first attempt to swallow, and that is when it is safe to remove the endotracheal tube, but you always have to check for reflux to make sure nothing goes back down to the lungs that shouldn't. If the patients don't recover in time (our animals are all from local shelters, so they are picked up to be taken back to the shelters at a specific time) it is the assistant surgeon that stays with them and is responsible for coming in that night and the next morning to check on them and write the SOAP. The SOAP is basically just how the dog is doing- you have your subjective and objective observations, your assessment, and your plant of action. If the dog appears painful on a check up we take them up to ICU for some pain meds. Luckily, since spays and neuters are elective surgeries (for the most part), the animals are usually in pretty good health and there aren't any serious complications. I had one dog that was slow to wake up and her body temperature just would not come up after surgery. She ended up staying the night, but she wasn't painful and while her temperature was still lower than average the next morning, it was higher than it had been the night before and her attitude and demeanor was much better and much more lively. So there is a lot more that matters than just textbook ranges.

Now that I'm done with my assistant surgeries, I am moving on the my three surgeries as the primary surgeon over the next two weeks. I'm not as nervous as I was for my first surgery as the assistant surgeon, but I'm still a little nervous to have all of that responsibility on me. At least now though I feel like I have a much better idea of what to do and how to do it. I just need to practice my interdermal suture closure before then.