Dead Dogs Tell No Tails

If you don’t get the titular reference, we have a grave problem for which the only cure is a Pirates of the Caribbean movie marathon.

Monday marked the point where we reached the back end of the dog. These last few months have seen an anatomical journey from nose to tail – which ended with ‘Pelvis’. Not, in fact, tail.

So far, I’d considered the contents of the pelvis to be the same as those in the abdomen, because unlike the boundary between thorax and abdomen, there’s no obvious divide. What this lecture really communicated was how things rounded off, wrapped up and continued to the outside world, and what muscles are involved in holding it all in. This lead to a rather uncomfortable image when our lecturer began telling us about her pelvic floor exercises.
Thanks, doc.

This was immediately followed by the chicken embryo practical which, as you might recall, was a round-up of our embryology lectures. In the teaching labs, our lecturer and a PhD student had set up a microscope with a transgenic embryo underneath. The student spent a little while talking to us. I sincerely don’t recall what she had to say because, come on, all I wanted was to see the baby chicken and get on with the rest of my classes.

When I finally did get the chance I peered in to see a fuzzy green shape, which sharpened into a little embryo when I turned the focus. It bore absolutely zero resemblance to a chicken, but it was vaguely tadpole-shaped, with a distinctive head region and tail. Various structures that we’d covered in lectures became apparent to me, but the single most beautiful was the little heart that was already beating outside the embryo’s body. It was steady, and much slower than my own. And it sat, beating away in the glow of its own eerie green light. All this had grown in just 60 hours.

After having seen the one they’d made earlier, it was time to make our own. Another lecturer sat with trays of fertilised eggs, and demonstrated the method we were going to use to get our embryos out of them. In doing so, she managed to botch no less than 4 attempts. Don’t get me wrong, it’s a fiddly process, but just as she cracked egg number 5, she said sheepishly, “You’re only allowed three eggs.”

Fabulous, I can tell this is going to go swimmingly.

Claire and I found a kit, cracked Egg 1 into a petri dish and looked for the little pale area of yolk. This is where we knew the embryo would be, where the yolk had begun to disintegrate to feed the growing chick. Thankful that Chicken Little had landed on the top of, and not under, the yolk, it was then an excruciatingly tense minute where I used a tissue to wipe albumen away from the embryo. The tissue picked up and pulled the gloopy whites away, right down to the membrane of the yolk. All that stood between my tissue and total yolk tsunami (in which the embryo would have been swept away), was a terrifyingly thin yolk membrane.

Taking a second to breathe once I felt enough was enough, we placed a little paper circle over the embryo so that it sat in the hole in the middle. After allowing the membrane to adhere to the paper I began using scissors, centimetres away from the 6 hour old life form, to cut the membrane around the paper. Then it was straight into a saline bath to wash the excess yolk from the underside of the membrane. If you leave too much, you won’t be able to see the embryo. I swished the paper about, praying that the embryo wouldn’t be swished off too. We then placed the paper into nutrient agar and rushed off to look at it under a microscope.

Once there, we scanned the paper for signs of life… and found nothing.

I distinctively recall seeing a small pale circle before washing the paper, known as the area pellucida, where the early embryo sits. But it wasn’t there now. Which could only mean I washed the poor thing right off.

Take 2 then.

Claire did the washing this time, and we erred on the side of caution, leaving a fairly yolky paper, but one which hopefully contained what we wanted.

Second look down the microscope… success! At first I wasn’t convinced, but our tutor confirmed the presence of a very early embryo. It wasn’t spectacular – a small pale circle with a faint grey line extending from its edge towards the centre.

But 24 hours later, after a night spent in a cosy incubator, this was the result:

embryo

Chicken Little Mark II

About half the age of the transgenic one I’d seen the day before, our embryo had come a long way overnight! It also resembled a tadpole, and you can clearly see its early spinal cord, with small dots running down alongside it. These are somites, and will go on to form bones, muscles and organs all in the right places.

Just to the bottom right of its head region is a small pale circle, which was beating slowly as we watched. Yep, at 30 hours old, it already had a tiny little working heart.

That night was the Dick Vet Pre-Burns supper. Hours before the event began, wine, in volumes I have never before set eyes on, began to arrive. Around 400 people attended, to watch our head of school crack the world’s worst one-liners. This was followed by an ace recitation of the Selkirk Grace by our very own Claire, and the haggis was paraded in by a vet student playing bagpipes.

Whilst waiting for the food to arrive, we moseyed between the table and the bar (free wine refills – don’t mind if I do!). But the same kind of casual indifference didn’t work when the food arrived. Little bowls of meat and potatoes were brought in by staff, who consistently missed our table. Completely unable to work out what was going on, the only available solution was to perform a haggis heist on the next unfortunate waiter. This we did twice, which still didn’t make a dent in the hunger we’d been experiencing since arriving at 8:30 am that morning.

But after a similarly microscopic dessert, a general-knowledge quiz was scheduled to start. Just before it did, one of my anatomy lecturers appeared at the table, sat down next to me and, slightly pissedly, began making slurred conversation. As funny as it was, we were relieved when she declared that she was going to ‘mingle’ and graced the next table with her company. She was still there an hour later.

But the next time I saw her we were face-to-face, trying to dismember a dead dog. I’m grateful that the task at hand demanded enough attention to avoid what could otherwise have been awkward eye contact. But then again, is forcefully dismembering a dog really any kind of bonding exercise?

This was our very last dog dissection. The tutor had begun by reminding us to take a moment to thank our dogs, to remember who they were and recognise that without them we wouldn’t have received the education that we have.

Believe me, the sentiment didn’t last long! Although we did spend a small amount of time identifying the different cavities of the pelvis, the majority of our time was actually spent attempting to split the dog right down the middle. After disengaging what muscles we could from the pelvis and its wings, the bone cutters made yet another appearance. Wedging them right down into the pubic symphysis, we crunched our way from front to back. My remorse got so bad that I actually apologised to the front half of the dog.

The instructions then told us to use the leg to lever one half of the pelvis away from the other, cutting the joint between the spine and the pelvis as we went. The mechanics of it all seemed very straight-forward but, try as we might, the pelvis refused to split. The dog lay on his back, two of us leaning on his right thigh and the third (me) stretching his left leg away from his body.

The table groaned, but bone was most definitely still stuck to bone. Redoubling my efforts, I put my weight onto his leg. Building up the pressure, I felt the bones bend with the stress.

*Crunch*

The leg collapsed under me.

Aha! For a second I thought we’d done it, but when I felt the looseness of the leg, I realised that the only progress I’d made was to break his hip. Dang it.

So we called for backup, and soon had three students, a lecturer and an assistant all pulling on the same dog. From a distance, it looked a little like CPR. The assistant jumped up and down on the left thigh, making noises like Serena Williams with each effort. The dog bounced, and the tray skidded in increments across the table, but to absolutely no avail.

So it was Plan C: hacksaw.

We assumed our positions. I helped Claire and Jacqueline pin down the right thigh, whilst the lecturer pressed on the left and the assistant sawed furiously through the sacroiliac joint.

It took a few minutes but, with a crack, the pelvis split into two pieces, and we were finally able to observe the structures we’d been looking for.

It really was with a bit of sadness that I said goodbye to our dogs. Dissections have been an absolute blast, and I’ve learnt so much from them. I don’t know for sure where these dogs came from or who they belonged to, if anyone at all. But they lived and loved and played once, and they’ve now done a great service by teaching the veterinary professionals of the future. And so in that way, they’re little life-saving heroes in themselves. I make light of our time in the dissection room, but I know that this kind of experience and learning opportunity is absolutely unrivaled, and my respect for the animal body has increased tenfold. So thank you, doggy pals!

Some of my favourite experiences and stories have come from dissections, but with these over, the practical classes are set to be very few and far between for the next 20-ish weeks. Hopefully I’ll still have plenty of other exciting times and stories to share with you here!

But I’ll round off this post with a story of live dogs, shall I?

Exams begin in just over 2 weeks. These will examine anatomy, histology and cell biology. In order to practice our anatomy, we took a trip up to the Edinburgh Dog & Cat Home, where they provided groups of us with a dog.

Dressed all in waterproofs, and stood in a freezing wet compound with 5 colleagues (including Claire!), we struggled to get our little dog to stand still. Toffee was a long-haired Jack Russel type with a terrific personality. Left to our own devices, we spent most of our session playing with the little man, who wished for nothing more than to have a bigger mouth, so that he wouldn’t have to choose between the tennis balls!

Now and again I’d be able to feel a lymph node while he played tug of war, but the rest of the time he spent dashing through my legs. It was only when our tutor arrived that she put him on a lead and began talking us through what to feel and look for. She made it look so easy, but stuff was still really difficult to find through all that hair!

It was a slight surprise, however, to feel his microchip sitting in the skin right at the front of his chest. Not unheard of, but still a novel experience for me. Examining dogs at all is still a novel experience, and I’m still slow to find things that I’m looking for. So don’t be surprised if you find me asking to borrow your dog for a quick second while I practice!

The next few weeks are predominantly filled with preparatory sessions for the February exams, but on my timetable I spy an ultrasound practical and a sheep foot-trimming practical lined up for this next week. Stay tuned!

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