How often does your day’s work bowl you over with amazement and excitement? Now, I am an annoyingly glass-half-full person, I have to say. So if one of the animals I see every day on my ambulatory tour of veterinary clinics helping with ophthalmic cases is an especially good example of a particular condition for the students driving around with me, I’m happy. It’s even better if I can get an excellent image that will go well on my Instagram (@bow_teye)! But the best cases are those that provide a perfect opportunity for some clinical research – that really floats my boat, as they say.
Perhaps I can tell you about last Friday: I travelled to a lovely clinic quite a way away from Cambridge, but one where the head vet has designed a wonderful clinic and employed fantastic vets – and even better, every Friday is cake day with one of the nurses an excellent cook! The only trouble is that fitting everything into the purpose-built clinic is not easy, given that it was designed to be a single-vet practice but now, given its popularity, has three or four vets alongside nurses and receptionists.
So, when I got there to see a little Boston Terrier with a white speck in one eye we had to wait for a bit. A quick glance showed me that I needed to dilate both pupils, so a quarter of an hour later there was a dark room to do a quick eye examination and a beautifully dilated pupil that showed three dots of dense white opacity, one at each end of the lens suture lines. There was some nuclear sclerosis there too as the dog was quite old, but nothing to cause any visual problems. All well and good. A bit of a distance to travel for one case but a lovely opportunity to reassure the owners that all was well and to show the A-level students on work experience how interesting it could be to link the basic science of embryology and anatomy with the clinical science of ophthalmology.
I’d found someone who gets as enthusiastic over cancer from a dog’s reproductive tract as I get about eyes!
I was about to leave when I noticed a dog just about to go into surgery to remove a nasty fungating mass from its vulva. “What’s that?”, I enquired in passing, though I had a sneaky suspicion I knew. “We don’t know,” came the reply, “that’s why we are sending it off for histopathology.” I asked where the dog was from. “It’s been rescued from Cyprus” was the response, which made perfect sense. Pattern recognition is a wonderful thing, and I had seen this before – from the eye but not the vulva, I have to say.
It was almost certain to be a transmissible venereal tumour (TVT). We happen to have one of the world experts in this fascinating neoplasm, Liz Murchison, working at the vet school in Cambridge and several of my students have worked in her lab. I knew that providing her with fresh tissue would be a great opportunity for setting up a new cell line with countless research projects coming from that.
Long story short, it took ages to contact her but when I managed to she was overjoyed by that news. I’d found someone who gets as enthusiastic over cancer from a dog’s reproductive tract as I get about eyes! It was 4.30pm on Friday afternoon by the time I got the tissue back to her, but there was time for a quick hug to celebrate before she got the sample cooled in dry ice and started her research – no time to waste!
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Liz’s lab has shown that these tumours all result from one tumour from 10,000 years ago, and they’ve spread around the world
Perhaps I can explain why this tumour is so exciting. TVT, as its name suggests, is a transmissible canine tumour spread by intercourse. You might ask what’s so special about that? We’ve known for years that human papillomavirus, spread through sex, can cause cervical cancer. Thankfully vaccination can reduce the incidence of it these days. But TVT is different. There’s no virus here. The actual neoplastic cells are spread from one dog to the other generating a new tumour directly growing from the transplanted neoplastic cells. Liz’s lab has shown that these tumours all result from one tumour from 10,000 years ago, and they’ve spread around the world. Why so rare in the UK then? You basically need a feral dog population mating indiscriminately to spread the cancer, just as there is in Cyprus but not in the UK, and hence why having fresh tissue within half an hour’s drive from Cambridge was so exciting. Exciting too because the cancer can be readily cured with vincristine, so good news for the dog as well as Liz’s lab group.
But could I be sure that this really was TVT? Liz was convinced by my picture of the mass and the dog’s relevant history. But the vets doing the surgery had taken an impression smear of the mass and I still had that slide with me in my pocket. The day after my visit, I had the delight of showing a teenager, who was keen to become a care assistant or maybe a vet nurse, around the vet school with her mum. What better opportunity to get her (the young lady not her mum!) to do a quick Diff-Quik stain of the slide and look down the microscope? Lo and behold, there were the TVT cells giving a perfect confirmation of the diagnosis.
What could be a better result than that – enough amazement and excitement to keep me going for a week at least!
