OK, so welcome everyone. This is, yet another and actually the 4th of the lectures that I'm delivering in this little series about oncology for the webinar vet. And as I mentioned in the previous one, so we're sort of going through some of the less common tumours that we, that we see in the head and neck area, in this hour and the actual the hour before, oral tumours is not one of the things that I'm covering, so I sort of consider that to be primarily a surgical disease.

And I am not a surgeon. I can't even spay a cat, so you wouldn't want me giving a lecture about how to approach an oral tumour surgically. So most of what I'll be talking about is again the sort of the medical management aspects of these less common tumours of the head and neck and the, the three that we're gonna be covering this particular hour, salivary gland, tonsil, and tongue.

And again, just as I've stated previously, one of the downsides of doing these sort of in a pre-recorded fashion, it's very nice and very convenient because you can view them at your leisure, but we don't have the opportunity to interact through, even sort of a text-based or a chat-based way to answer questions in real time. So please do not hesitate to reach out by email. You can use that email that's right at the bottom of the slide.

If you do have any questions about the content of this lecture or any of the other lectures. That I've actually covered in this series. And so with that, why don't we go ahead and get started talking about salivary gland tumours.

So salivary gland tumours are actually fairly rare in both dogs and cats, but we do see them occasionally and actually sort of, male cats and cats of the Siamese and other related oriental breeds may be predisposed, so we may actually see them a little bit more in those oriental breeds. By far and away, carcinoma, so adenocarcinomas, so tumours that are driving, driving from the gland itself, are the most common type of, salivary tumours that we see. Occasionally, we can see other things that actually arise from the salivary gland, so the occasional mass cell tumour, the occasional what we call extraskeletal osteosarcoma has been reported in the salivary gland, but really, you know, 95+% of these.

Are going to be carcinomas. We tend to not see a huge percentage of benign salivary gland tumours like adenomas, but occasionally those can be seen as well. Any gland can be affected and sort of just again looking at the anatomy of the salivary glands in the bottom, little figure here.

Again, any of the glands that we see can theoretically be affected. But in dogs, actually, we're most likely to see the mandibular gland affected, and cats, it's most likely to be the parotid glands. And again, interestingly, despite the fact that we don't have occasion to submit salivary glands, all that common for histopathology, about a third of all the salivary glands that are submit submitted for histopathology do end up excuse me, end up being neoplastic.

So, how's a dog with a salivary gland tumour likely to present at your clinic? So by far and away, this is again another one of those circumstances where they're likely to be presented for a palpable mass, sort of externally, that the owners have felt or the groomers have felt, or that you have felt on your physical examination. Occasionally, we could see an a dog present for dysphagia, again, halitosis or exothalmos, depending on the gland, the specific salivary gland that is affected.

So, obviously, these submandibular masses, can be seen with some frequency and, obviously not all of them are going to be, salivary gland tumours. So salivary gland tumours would be one thing to put on the list. I think perhaps something that we see with a bit more frequency would be salivary mucousces that can occur in this sort of submandibular regions.

We We can see syabitis, either inflammatory or infectious in origin. We can see abscesses, secondary to foreign bodies, things like that. There are lots of lymph nodes that live in this area as well, so sometimes we may have a disease process that feels like it's arising from salivary gland where where we're actually feeling is one of the cervical lymph nodes that could either be reactive or metastatic.

And then lymphoma, we could certainly see regional lymphadenopathy from a systemic disease like, lymphoma that could also again feel kind of in the same region as what we would see with salivary gland. The final thing that I'll add to this list, although it's usually in a slightly different location. Would be a carotid body tumour.

So these are also called carotid body chemodommas that kind of occur, again, as the name implies kind of in the, in the carotid region of the neck, so it's usually a little bit more lateralizing than what we would generally associate with submandibular, but can, we can see that as well. So just like with most other kind of masses or lumps and bumps that we tend to observe in our patients, one of the first things that we'll generally consider is a fine needle aspirate, of the primary mass. And again, usually at the same time we're immediately following, I'll try and get an aspirrate of the regional lymph node as well, if I can feel it at all.

And again, so here's sort of the classic cytologic appearance for a carcinoma. Again, this isn't specific for salivary gland carcinoma, this does happen to be one. So again, you can see, these sort of clusters of cells that sort of appear to be arranging themselves around sort of a central hole in this case, sort of an insinophilic area.

So this is what's called an asiner structure, this sort of gland-like sort of structure that you can see even on cytology. And again, there's some variability in size and shape, a relatively high nuclear cytoplasmic ratio, very dense, cytoplasm, densely basophilic cytoplasm. Again, a fair number of these cells on high power appear to sort of contain this, this light coloured secretory material, which in this case is actually saliva.

And again, so the cells sort of are sticking to each other, but there's quite a bit of variation in cell size and shape. The nuclei are, kind of eccentric, so they're not in the centre of the cell, but kind of pushed off to one side, and you can see one very prominent nucleolus in most of these cells as well. So several of the factors that we would associate with malignancy here.

Again, we do like to look at that regional lymph node, and about a third of cases may have lymph node involvement at the time of surgery or at the time of presentation. So this definitely is something that's worth interrogating because again, obviously, if, if we do have a case who does have lymph node involvement, we wanna know that to make sure that those lymph nodes are addressed properly at the time of primary tumour treatment. Chest X-rays again are also an important part of our, our work up here.

And again, between 8 and 15% or so of, of animals with thyroid tumours may in fact have evidence of disease in their thorax as well. And in those cases, again, unless it's needed for, for palliation of some kind of clinical sign, really these animals then sort of do not become surgical candidates. So it's a really sort of critical piece of information because finding metastatic disease in the thorax.

Is certainly a surgical showstopper. CT, or other kinds of advanced imaging MR can also be used, can be very, very useful for surgical planning. And again, this really gives us three pieces of information that can be very useful.

So one is it does sort of allow us to get a better handle on sort of what structures may be incorporated into this tumour mass. So if we do try to go in there and, and scoop it out, what kinds of things do we have to be very careful to avoid or to incorporate, etc. Etc.

Here's kind of a neat 3D reconstruction of a tumour where you can see these very large vessels that are sort of coursing right over the top of it. So this is the kind of thing that's actually very helpful to know. When you're planning your surgical approach.

It also allows us simultaneously to be able to assess the regional lymph nodes. And again, some of the regional lymph nodes that we may encounter as, as, the first lymph nodes to be involved in a case like this could be, for example, retropharyngeal lymph nodes, which are not palpable externally very easily. So you may see significant enlargement or heterogeneity of the retropharyngeal lymph nodes, even if the submandibular lymph nodes appear normal.

So again, that piece of information is quite helpful. And again, the third piece of information that can be very useful or the third, the third utility for, for getting advanced imaging like a CT scan is if in fact the tumour is deemed unresectable, the images that are obtained from the CT can be utilised for radiation planning. This is not the case with MR.

So MR gives you a beautiful, beautiful tissue images, but it is not possible to plan radiation therapy generally from an MRI, so hence, again, the recommendation for CT for a lot of these. And again, contrast CT is actually quite helpful. These masses do tend to, generally uptake contrast in a way that does help to delineate them versus doing a purely non-contrast CT.

So surgical excision is the treatment of choice, and just due to the sort of the geographic restrictions that are present, It does appear that a lot of these excisions are going to be incomplete. So sometimes we do see these very nice well encapsulated tumours that come out quite nicely and, and truly we do have a complete excision, but quite a lot of these are gonna be incomplete. And thankfully, actually, these are tumours where postoperative radiation therapy can be quite effective.

So in many of these cases where excision is incomplete, local recurrence is our major concern, and that can actually be prevented quite nicely with postoperative radiation therapy. Again, the kind of radiation that we're talking about when it's used postoperatively is generally several weeks of daily treatment, somewhere between sort of 15 and 18 daily Monday through Friday treatments. Most dogs will actually tolerate this form of radiation therapy quite well.

And again, it does seem like the limited information that we have suggests that recurrence is significantly either delayed or prevented with the use of postoperative radiation therapy. So what about chemotherapy? In these cases.

So either if radiation therapy is not feasible and we do have an incomplete excision, or for example, we do have a, have disease in the lymph node and we're concerned about the possibility that this tumour could end up metastasizing further down the line. So again, these are rare enough tumours that we really don't have any meaningful statistics or percentages about the outcome with any sort of medical therapy. But in those cases where we have unresectable disease or metastatic disease or disease that we would consider at high risk for recurrence or metastasis, I certainly don't hesitate to talk to owners about the possibility of, of post-operative chemotherapy to try and delay or prevent recurrence or metastasis.

Again, based on what we know about treating other carcinomas in dogs or cats. I think the reasonable sort of empiric choices that we would, that we would make would be drugs like carboplatin or doxorubicin, with or without a non-steroidal anti-inflammatory drug, added on. So again, very important for owners to understand that these are uncommon enough tumours.

We simply don't have any meaningful statistics or percentages to be able to quote about efficacy, but I do think it's something that I do feel comfortable recommending because of its possibility to help at least. So what is the prognosis for these dogs, and cats. So really interestingly, we're basing almost all of our knowledge about salivary gland tumours in dogs and cats from one paper that was published going up on 20 years ago, actually.

It was, it was a moderately sized paper that actually looked at dogs and cats together and then sort of broke them out separately for outcome. And the average dog or cat, That that has one of these tumours, has a, a media survival time in the neighbourhood of about a year and a half. And about 40% of dogs will make it to 3 years.

That number tends to be less in the cats. And again, node positive cases are statistically associated with the worst outcome. So again, these are the situations where if in fact we do have a case with disease in the lymph node, at least offering to follow up with additional therapy that might be beneficial, is worth considering, I think.

But again, a reasonably good outcome, with surgery, plus or minus additional therapy. And honestly, I would argue that it's been long enough. We've treated enough more of these that this is a tumour type that's really ripe for additional study.

And I think some additional retrospective analysis of how these patients have fared over the last 20 years would actually be potentially very valuable and, and something that I think I, I hope is actually in process. So, moving on. Next tumour type that we're gonna talk about in this lecture are tumours of the tonsil.

So, by far and away, the most common tumour type, primary tumour type that we see occur in the tonsil, is squamous cell carcinoma. However, we certainly can see some other tumours developed there either as a site of metastasis. So for example, we can see oral melanomas, sometimes metastasized to the tonsil, and we certainly can also see tonsil or involvement from systemic diseases like lymphoma, in dogs and cats, although again, contrary to what we see in cats with lymphoma in the nose, when we see tonsilar involvement, it's usually part of a multicentric presentation.

And not sort of a standalone site of disease. Again, like we talked about with nasal tumours, it does appear that in some studies, oral squamous cell carcinoma, or tonsillar squamous cell carcinoma may be more common in urban environments versus rural environments, which could suggest some kind of environmental contribution, to the pathogenesis of this disease. So, how's a dog with this disease likely to show up at your practise?

So this is kind of an interesting one, and I do think one that's probably worth remembering. So, more often than not, Dogs with these tonsillar squamous cell carcinomas may present for a submandibular mass. So, again, a presentation not at all dissimilar from what we just talked about for dogs with salivary neoplasia.

So often it's the submandibular or mandibular swelling that's gonna be the presenting complaint, not, clinical signs related to the primary tumour. Although occasionally we certainly can have dogs who present for signs that would be consistent with other kinds of oral neoplasia. So, cough, respiratory stridor, dysphagia, those kinds of things.

And honestly, we, there are a fair number of these that can be detected at the time of intubation for something else. So the dog's being intubated to have a dental performed. The dog's being intubated for, you know, some other kind of elective surgical procedure and lo and behold, actually you see this tonsillar abnormality and the the biopsy can be obtained then.

But again, this is one of the presentations that I do think is worth remembering. So in a situation like this, again, we can achieve a diagnosis fairly simply through fine needle aspiration cytology, of this very prominent submandibular mass. And what you can see is, Again, these are sort of normal lymphoid cells in this part and then over here you can see this, this population of really huge, very, very bizarre, clusters of, epithelial cells.

And again, these have a very sort of basophilic cytoplasm and the cytoplasm has this, this kind of appearance that's often referred to as a ground glass appearance. And again, in this case, the cytoplasm is full of keratin, and actually the keratin is what's made by these squamous epithelial cells that have become malignant. So, again, this can be a quick and easy way to achieve a diagnosis.

So if you find a dog who presents again with this sort of unilateral, what feels like a lymphadenopathy in the cervical region and you aspirate it, and you get back a diagnosis that's consistent with With squamous cell carcinoma, metastatic squamous cell carcinoma, definitely, definitely look at the tonsil for your primary tumour location. That's by far and away going to be the most common primary tumour location if you get back metastatic squamous cell carcinoma from a, from a cervical lymph node. And so here's an example of what that, that would look like.

So here's a dog who's intubated. You can see this is our laryngoscope right here or just about to be intubated. And again, you can see the sort of large irregular kind of erythematous slash slash hemorrhagic tonsillar mass that sort of overriding up onto the, up onto the sort of the dorsal soft palate and sometimes upper overriding up sort of into the area of the larynx as well.

So these tend to be very, very infiltrative. And obviously, as you've guessed from the, the clinical presentation that I described previously, they are associated with a very, very high metastatic potential as well. So, again, about 10 to 20% of these animals may have evidence of metastasis in the thorax, at the time of presentation.

So again, thoracic radiographs are another very, very important component of this because it does change how we'd approach the primary and or lymph node disease. Just like we talked about with the with the salivary gland tumours, a CT scan for radiation therapy and or surgical planning can also be very useful so we can get a better understanding of exactly where these tumours begin and end. So again, if we are going to attempt surgery, what exactly is gonna have to come out and is it actually safe to remove that stuff?

So surgical excision is the treatment of choice for dogs who have local disease or local regional disease, so disease that's relegated just to the regional lymph nodes but not beyond. But unfortunately, we think about 90% of these dogs, even if their thorax, for example, is, is is normal at the time of presentation, probably do have evidence of microscopic metastatic disease beyond the node or beyond the primary site if the node is OK. So whenever possible, we do try to do surgery both to the primary tumour and to the regional lymph node.

Although again, based on how infiltrative some of these tumours are, are, it is definitely not always possible to do surgery. There's a small case series of, of dogs who actually received a combination of, of debulking surgery followed by radiation therapy. And again, they had a relatively low, median survival time.

So the median survival time was only about 4 months. Although local control was quite good. So in other words, 3/4 of these dogs did not have clinical signs or die as a result of their primary tumour.

But they certainly did develop eventual metastatic disease. And again, this is a very old paper where the radiation therapy that was used isn't quite as sophisticated as it is today, but I'm not convinced that the results will be any different with just radiation therapy to the primary site. So what about medical therapy for this disease?

So, one of the things that we certainly would consider as part of the treatment is some kind of non-steroidal anti-inflammatory drug. Piroxicam is the one that has been best studied for this disease. And actually, you'll get a lot of differing opinions from different oncologists about whether all non-steroidal anti-inflammatory drugs are created equal or whether perhaps there's something that could be unique about paroxicam.

And it's mechanism of action that may make it a superior anti-tumor drug. Again, I think that oncologists are probably literally split fifty-fifty about whether they feel, again, all NSAIDs are the same or whether there's something special about paroxicam. So again, don't judge your oncologist if they if they prefer one over the other.

I personally like paroxicam. It's very, very inexpensive, at least here in the States. It's only given once a day.

It's given properly, so don't round up in your dose, give it with food. Don't mix it up with any other potentially ulcergenic drugs. Most dogs do tend to tolerate it very, very well.

And certainly I do feel like we have the most information about its anti-tumor effects compared to the other NSAID. So for those reasons, I do tend to reach for it, but it's by no means the only choice. So, we do know that the majority of squamous cell carcinomas in dogs of all locations, actually do tend to express the cycle oxygenase 2 enzyme, which is the target of of these non-steroidal anti-inflammatory drugs.

And in one relatively small case series of all oral squamous cell carcinomas, not just in the tonsil, about 20% of these dogs actually had meaningful tumour shrinkage, including one complete response. And in those 3 dogs that actually experienced tumour shrinkage, their median response duration was about 180 days, about 6 months. There's another very small, again, very, very small case series of about 5 dogs that were treated with a combination of carboplatin, once weekly palliative radiation therapy, and again, they had a median survival time of about 7 months.

So, definitely something that's worth considering. This combination of local therapy, either surgery or, or some form of radiation therapy, whether it's palliative or whether it's more sort of quote unquote curative intent with some kind of medical therapy. And again, be it a non-steroidal anti-inflammatory drug, be it carboplatin, or potentially be it a bit of both of them.

So here's another relatively recent paper that came out. Jerry Poulton was the the senior author on this and it came out in JSAP. That looked at 44 cases of tonsillar squamous cell carcinoma that were treated actually with a variety of different modalities.

So you can see there's a handful of dogs that had no treatment, NSAIDs alone, surgery plus NSAIDs, add chemotherapy to that, add radiation therapy to that, and then again a variety of all these different possibilities. And when we look at their outcome, if you put everybody together, their overall median survival time was about 6 months. And actually, that, that particular number includes the 8 dogs that got nothing.

So, still a very, very aggressive disease, but I think this does imply that that this is a disease that is worth treating. And that we are able to at least sort of kick the can down the road a bit with our treatment. So the likelihood of cure is probably quite low, but do we have the ability to actually keep these dogs doing well for a longer period of time with therapy?

Absolutely. I certainly think we do. And again, here are just a few of the different therapies that were investigated in this study, where there were enough cases to have some sort of, sort of ability to calculate statistics.

And again, those dogs who received no therapy at all had a median survival time of about 2 months. Those dogs who had surgery alone had a median survival time of around 4 months. Those dogs who were treated with medical therapy, so chemotherapy or, that would include chemotherapy plus an NSAID, had a immediate survival time of about 7 months and those dogs that had radiation therapy and chemo did well for an average of about a year.

So I do feel pretty Strongly that although the statistics that we have are unfortunately weak, this is one of those two types where within reason, kind of the more we do, the better the potential outcome, at least in the short to intermediate term. Although I do think it's very, very important to impress upon owners that this is a disease with a very, very high metastatic potential and overall, the majority of patients that we treat will ultimately succumb for, to this disease. One drug that I will mention because I believe it may still be available in the EU is Paalva.

So Paa that's no longer available in the United States. But this is actually a novel formulation of a drug called Paclitaxel. So paclitaxel, is actually a drug that's used all the time in human oncology.

So the most common brand name of this drug is Taxol. And Taxol has a great deal of, of anti-tumor activity in a wide variety of different human carcinomas. So squamous cell carcinoma, breast cancer, lung cancer, prostate cancer, bladder cancer, etc.

It's used for a wide variety of different carcinomas. And while sort of conventional Taxol can be given to dogs, the vehicle in which that Taxol is delivered actually is associated with an extremely high likelihood of sometimes quite severe hypersensitivity reaction. So it's actually a very difficult drug to administer to dogs because they're very, very sensitive to this, this vehicle in which it's delivered, which is called cremaor EL.

So Pack out that was actually developed by a Swedish company, that used a different kind of vehicle that is not associated with the same risk of hypersensitivity. And again, in some of the preliminary studies that were done with this drug, 17 dogs with squamous cell carcinoma were treated, and about 5 of those dogs actually had meaningful tumour shrinkage. Again, this was not purely, oral or even tonsilar squamous cell carcinoma, but squamous cell carcinomas of all locations.

And the response durations ranged from as short as 2 months to more than a year. If you took a look at all the dogs and put them together, the overall median progression for interval was about 2 months. But again, so if you're lucky enough to fall into the 3rd or so of dogs that respond, some of those responses can actually be fairly durable.

So again, this is a drug that's no longer currently available in the United States, but I believe it may still be available in the EU. So would unquestionably be a consideration along with drugs like carboplatin. And, and the NSAIDs for management of an unresectable or metastatic squamous cell carcinoma, actually be it of the tonsil, or be it of another anatomic location.

And then, again, there's some preliminary evidence from a, a somewhat unscientific, retrospective study that was performed, and I feel comfortable saying that because I was one of the co-authors and can, can attest to it's unscientific nature. So this is actually a survey-based retrospective, case series of animals with a variety of different kinds of neoplasia that were treated with palladia, the Zoidas mast cell tumour drug. Who had a variety of different solid tumours other than mast cell tumours.

And importantly, These dogs were not all treated with Palaia or tocerinib as a single agent. Some of these dogs were co-treated with non-steroidal anti-inflammatory drugs. Some of these dogs were co-treated with things like metronomic cyclophosphamide or metronomic chloriambuil.

So, it is worth sort of keeping that in mind. But again, here are some of the tumour types where enough cases were collected that at least some, some percentages could be reported. And again, one of them is squamous cell carcinoma.

So about 8 dogs with squamous cell carcinoma were treated. And again, in this very, very small case series, about 7 out of 8 of these patients, I'm sorry, I guess it would be 6 out of 8 of these patients actually experienced meaningful tumour shrinkage. So, again, the majority of the, of the tumour responses that were observed were partial responses, not complete disappearance of all evidence of disease, but partial improvement.

And it looks like the median progression free interval on these patients was around 20 weeks or so. So that translates to what, about 5 months or so. So again, I really would not want to hang my hat on these statistics, these numbers, these percentages based on such a small and such a biassed, potentially biassed population of patients.

But one of the things that I do think that this, that suggests is that there are probably some patients. With squamous cell carcinoma as well as these other tumour types who could certainly benefit from from treatment with palladia. Again, when we tend to use palladia in a situation like this here, We generally don't use it as a single agent, but we're much more likely to combine it with an NSAID given on the off days from the palladia and metronomic cyclophosphamide, actually.

. So again, I wouldn't want to sort of look at an owner and say, oh look, there's a 75% chance we're gonna make a tumour, your dog's tumour shrink if we give him pellaia based on this end of 8, kind of poorly conducted retrospective study. But I do think it's kind of interesting data and it certainly warrants additional attention. When I am faced with, a case like this, I'll just show you, a little before and after picture.

So this was a dog with actually a maxillary squamous cell carcinoma, who experienced a nice partial response, following treatment. So when I am, treating a dog with gross or unresectable tonsil or squamous cell carcinoma, and I'm looking for a medical therapy option, I do tend to reach for an NSAID plus, a drug like carboplatin first. Again, there is a, a small case series that suggests clinical benefit in dogs with squamous cell carcinoma with that combination.

And again, in my practise, I find carboplatin to actually be significantly better tolerated than palladia. So we can find a dose of palladia that will work for the individual dog, but really we do see quite a bit more, primarily gastrointestinal side effects from the palladia. Then we tend to see from the injectable drugs like carboplatin.

So, ladia is definitely in our arsenal. But I'll generally start with injectable treatments first if I'm trying to manage one of these cases with drugs. And again, take home, I do really think that multimodality treatment, so some kind of combination of local therapy, be it, either surgery if possible, or radiation therapy, or in some cases both, and medical therapy, whether that's an NSAID, whether that's combined with chemotherapy, whether there's some palladia on board at some point along the line.

Really, the, the current data that we have does suggest that this kind of multimodality approach is superior. And that's the way we try to approach these cases. And then last but not least, we'll talk very quickly about tongue tumours.

So there are multiple different kinds of tumours that can actually, where, that can actually be seen in the tongue. And actually, about half of all the tongue samples that are submitted for histopathology do end up being neoplastic. Of those neoplastic submissions, about 2/3 are malignant and the most common histotypes that we see are melanoma.

And squamous cell carcinoma, which actually happen to be the two most common oral tumours that we see in other locations in the oral cavity as well. Then we can see hemangiosarcoma, we can see, soft tissue sarcomas like fibrosarcoma, and then a few other atypical things, mass cell tumours, lymphomas, other less common sarcomas, etc. But then there are also about a third of these tongue tumours that can be benign.

And we can see things like papillomass, viral papillomass, granular cell myoblastomas, which is kind of an odd, tumour that we don't see in most of most other locations, also called glomus tumour. And then we can also see some oral plasma cytomas or plasma cell tumours that can occur in the tongue. So clinical presentation, again, most of these dogs are going to show up for dysphagia, halitosis, etc.

And you may or may not be able to actually see a tongue mass externally. So, this one is obviously a melanoma, that's sort of classic pigmented, melanoma, arising on the ventral surface of the tongue here, we have a squamous cell carcinoma, and this is a common location actually for us to see squamous cell carcinoma in cats as well. And then here's another example of squamous cell carcinoma where it's actually occurring along the margin, the lateral margin of the tongue rather than occurring, kind of on the ventral surface or in the body of the tongue, and these are all possibilities.

So this is an example of a dog with viral papillomatosis. So this is a disease that's generally seen in younger dogs, not exclusively, but generally seen in younger dogs, or dogs that are on chronic immunosuppressive therapy. So chronic corticosteroids or drugs like cyclosporin.

Which may be needed for management of autoimmune disease or itchy skin or things like that. And this little guy here is kind of the classic appearance for one of these granular cell myoblastomas, also referred to as a glomus tumour. So again, as, as we always like to say, our eyes are not microscopes and we can't say that this is obviously 100% going to be something benign based on its gross appearance, we would always want histopathology to confirm that.

One of the other little things that's also worth considering is that we can actually see ectopic thyroid tumours occur in a sublingual location in some dogs. And here's actually a fairly large case series of 41 dogs with actually sublingual ectopic thyroid tumours. So here's a, a thyroid scan that was actually performed.

Actually demonstrating uptake in that sort of submandibular region. So here's our normal thyroid, and again, here's that, that submandibular region, which is not where we normally expect the thyroid to be, but as we like to impress upon the students, we can actually see ectopic thyroid tissue occur not only in the neck, but anywhere from the heart base all the way to the base of the tongue slash sublingual region. So that is something else that we would want to keep on our differential list.

So, there are some breed, breed predispositions to certain kinds of tongue tumours that we can see. So, chow chows and sharpei seem to be at increased risk for melanoma. Poodles, labs and samoids appear to be at increased risk for squamous cell.

Border collies tend to be at increased risk for tongue hemangiosarcoma, and we tend to see a bit more tongue sarcomas in golden retrievers. So again, all things to consider. So in cats, by far and away, oral squamous cell carcinoma is the most common tongue tumour that we see.

Probably 90% of the tongue tumours are squamous cell carcinoma. And unfortunately, these are usually occurring in the sublingual region, and involve the frenulum and actually can sort of extend and infiltrate down into the floor of the mouth, sort of in that intermandibular space, which really makes surgical resection on impossible for these cases. A typical presentation for these dogs is gonna be signs related to, that space occupying mass in the mouth, so halitosis.

Dysphagia, tyism, oral discharge, so blood or other kinds of, oral discharge in the water bowl. Sometimes we can again see sort of thick ropey saliva that occurs. And actually owners may be a little bit more likely to see the mass itself on the tongue of their dog than it is for us to see that with some of the other forms of oral neoplasia because obviously, dogs pant and you can see their tongues when they're drinking water and things like that.

So again, just like with the other tumours that we've talked about in the head and neck region, really we do like to evaluate that regional lymph node whenever possible and definitely interrogate it cytologically if it's enlarged, like we talked about with nasal tumours. This can really be a quick and easy way to achieve a diagnosis of a disease where, again, it might otherwise require sedation or anaesthesia and a biopsy and things like that. So again, comparatively quite simple.

And again, if we're able to obtain a diagnosis, in this case, this is a dog with a really big submandibular lymph node who actually has a metastatic melanoma, again, that's a, that's a, a quite simple way to actually for us to tell the owner what's going on, and often they're very appreciative of that. I guess another little sort of take home message that I'll mention is if we're gonna need to sedate a dog, for an oral examination for, and we see a tumour that's really anywhere in the oral cavity, I'll usually do anything in my power to actually get a biopsy while I'm doing that versus cytology. Because again, God forbid we actually sedated the dog.

We got a fine needle aspirin and it's non-diagnostic. We then have to re-sedate that patient. I, I think owners much prefer sort of a one and done approach here.

Well, if I'm gonna sedate the dog anyway, let's just take a piece of whatever we find that's abnormal versus again, cytologic sampling with it's higher inherent risk of a non-diagnostic sample that might require re-sedation. Chest X-rays, again, I keep harping on this, but I do think it's a very, very useful test to do. How likely metastasis is in the thorax is really gonna depend a lot on your primary disease process.

So, our, our metastatic risk is gonna be much higher for melanoma, for example, than it will be if we've got a soft tissue sarcoma or a benign tumour of the tongue, but definitely something that's worth doing. Surgical excision is actually the treatment of choice for most tongue tumours. And again, it takes a, it takes a fairly brave surgeon, but 40 to 60% of the tongue can actually be excised with fairly minimal complications.

So you can take it all the way back to the frenulum and actually these dogs tend to do very, very well clinically. Again, there can be an adjustment period where they need some, they need some help with eating and drinking and things like that, but the end result is generally quite excellent. So marginal excision, if you have a tumour that you know is benign, so for example, one of these glomus tumours or a tongue plasma cytoma, you don't have to actually do full thickness resection of the tongue but can actually do a partial thickness, marginal excision and again, often the outcome can be very, very good with these tumours.

So post-op management of these glossectomy patients, quite often if we are gonna be taking out a fairly significant amount of the tongue, we will recommend that we put in an esophagostomy or gastrostomy tube at the time for immediate post-op care. Again, there can be a week or two period of time when the, when the dogs actually sort of get things figured out. How to eat and drink again with that shortened tongue that they have, etc.

And sort of making sure that we're able to give them meds, make sure they sort of maintain adequate nutrition and hydration during that period while they're getting things figured out. It's actually a very useful little insurance policy. And when we can Explain to the owners that this is only a short-term measure.

It's not like what a quote unquote feeding tube would be in a, in a, you know, human in a vegetative state, etc. Usually, owners are actually quite happy that they have those. A couple of little tips and tricks that can be useful.

Feeding meatballs of food, of canned food rather than a dry like a slurry or dry food actually helps the the dogs to sort of pre-hand those meatballs with their teeth and learn how to kind of toss them into the back of their throat, and that actually can work very, very well. And the other thing as far as drinking goes is if your tongue has been shortened enough so that you really can't lap water effectively, what works great is actually if you, if you provide those dogs with a deep, water bowl. that they can actually get the, the commissures of their lips down under the water and they actually learn how to suck up water, very much like a horse drinks, sort of through their teeth, using, again, their entire mouth.

It actually works quite well. Theoretically, there are thermoregulation concerns that have been brought up, so dogs can't. And they actually get rid of, get rid of heat as a result of that, that sort of evaporative cooling through the tongue.

But again, in the majority of cases that where this has been looked at sort of scientifically, it really doesn't appear that there have been a lot of thermal regulation, issues. So here's one very small case series from about 15 years ago. It's only 5 dogs, but these are all dogs who had complete glossectomies.

So these dogs had like either all or like 80 to 90% of their tongues removed. So I think 2 or 3 of these cases were from tumours. There were 2 cases that were actually traumatic in origin, and this is really horrible, but actually both of those dogs got their tongues caught in a paper shredder and you can imagine what happened next.

But again, so, actually 4 out of the or all these dogs were able to eat without assistance after surgery and 4 out of 5 were able to drink. Again, one of them never really quite figured out the drinking thing and so needed to E tube for that. There were no heat tolerance issues and all of them did have sort of chronic drooly type problems, as a result of just, issues handling their own secretions, but again, that's a, that's a cosmetic issue.

It wasn't really a clinically relevant issue for them. So, radiation therapy, what about that? You know, we talk about radiation therapy for a lot of other kinds of tumours.

The tongue really does not like, to, to have high doses of radiation put to it. So there are acute side effects that are very problematic. And actually, the tongue is also very subject to a late fibrosis that can develop.

It's called, it's called wooden tongue syndrome and actually, that can be life-limiting because the tongue simply doesn't work correctly as a result of that. So curative intent radiation therapy is not something that we generally will push very hard for tongue tumours, but palliative radiation therapy can actually be quite useful. So a few doses, relatively low, given infrequently to help to sort of control clinical signs and actually with diseases like melanoma and plasma cell tumour actually can be often associated with meaningful tumour shrinkage.

How about chemotherapy or other kinds of medical therapy? So if we have tongue tumours, we will certainly talk to the owners about chemotherapy, and the same options as we discussed about for tonsil, squamous cell carcinoma. For melanoma, certainly many of you may be aware of this vaccine called ANET which is available through Barringer Engleheim that that can be potentially useful for the management of some postoperatively treated or treated with radiation melanomas.

So that would be another thing to consider as well. So what's the outcome in these patients? So, again, across all the different kinds of tongue tumours, here's one study that reported a median survival time of, you know, in excess of 4 to 5 years for benign tumours, so those dogs are effectively cured.

And a median survival time of about 286 days. So what's that? That's about 9 months or so, for dogs with sort of all sorts of malignant tumours put together.

And actually, in this particular study, there wasn't any major difference between the different forms of malignant tumours that were observed, but the tumour size, and, margins, so whether excision was complete or incomplete, were the two things that were associated with the biggest effect on prognosis. So here's another study that looked at about 100 cases that were treated retrospectively. And again, median survival time was in that sort of 7 to 8 month range for dogs with the typical malignant tumours that we see like squamous cell carcinoma and and, melanoma.

About a quarter of the dogs developed local recurrence, about 25% of the dogs developed metastasis. And again, size, and in this case, the presence of metastatic disease were the, the biggest prognostic factors that helped us to determine again whether an individual dog is likely to be put on the high side or the low side of these these median marks that we're so good at reporting. So, there is a histologic grading schema that's been proposed for squamous cell carcinoma of the tongue.

Again, this is a very, very old study that looked at the things that you can see there. I'm not gonna read them off to you, but you can see that if you do have a dog whose tumour was reported as low grade, or grade one, the outcome in these patients does have the potential to be significantly better than those patients with intermediate or high grade tumours. So again, this is not a ubiquitously utilised grading scheme, the way the mast cell tumour grading scheme, for example, is.

So I wouldn't, you know, call up and, and, read your pathologist the Riot Act if they don't assign a grade to the tongue squamous cell carcinoma that you sent in. But again, if terms like low grade are used, I do get a bit more optimistic based on this one very small paper. So I did mention that something like 10% of the tongue tumours that were seen in one very large case series out of a, out of a pathology database were actually hemangiosarcoma.

So, how well do these patients do? So this is a little retrospective study that actually came out of our institution. Barbara Biller was the first, the senior author on this paper.

And actually, all of the heangiosarcomas that were observed on the tongue, were read out as lower intermediate grade histologically and actually occurred on the ventral surface of the tongue. And actually, the median survival time in this group of patients was about 18 months, in many cases with surgery alone. Again, this is a retrospective study, so a bit of a mixed bag.

Some of these patients did receive chemotherapy as well. But about half the patients did have their tumours grow back, and those were mostly the incompletely resected tumours, and about half of these tumours did metastasize eventually. Tumour size again, and the presence of clinical signs.

So were these discovered accidentally or incidentally, or did these dogs present with signs? Were the two things that were identified as, as, being prognostic? So this is kind of an interesting exception to this rule that oh all hemangiosarcomas are terrible and everybody's gonna die.

These tongue hemangiosarcomas, I think based on the fact that we have a 45% metastatic rate in this study, we still do want to stage these patients very thoroughly like we would for hemangiosarcomas of other locations. And I do think it's worth offering postoperative chemotherapy for these patients. But again, based on this one relatively small retrospective study, The outcome with this particular disease may be a bit more optimistic than what we generally associate with most other forms of hemangiosarcoma.

So probably, you know, a good, a good little piece of information to, to talk in the back of your mind in case you do ever see one of these. And with that, again, our little tour through the less common tumours, in the head and neck region, is complete. And, again, as I, as I've said with all these other lectures, I'm more than happy to entertain any questions that you'd like to ask via email.

I'm sorry that we're not able to do that in real time, but again, I love to hear questions from you guys. It certainly lets me know that everybody was interested, and again, they can be about any of the lectures that you've heard or really any other oncology questions that you might have. And again, I thank you very kindly for your attention.