Thank you, Bruce, and thank you to everyone for tuning in at home. So, we're gonna start with a few questions. This ladies and gentlemen is Darren, a six year old male neutered German Shepherd dog with a horrible osteolytic lesion and a non-weight bearing lameness in the right forelimb.

What's your differentials for that? Just have a think. Question two, we've got Misha, a 10 year old female neutered miniature schnauzer, and Misha's presented with several days, really, really severe tensmus, dyschesia and hematochezia.

And on rectal exam and subsequent colonoscopy, you can see this horrible annular mass a few inches into the colon. And when you do some staging, you see. Some metastases in the lungs.

What's your differentials for this? And finally we've got Claudia, a 9 year old female neutered golden retriever, and over the course of about 7-10 days, progressively each one of Claudia's nipples turned black and then dropped off. And that's both on the right side.

OK. So you might have thought the first case, osteosarcoma, seemed fair. Second case, rectal carcinoma with metastases in the lungs.

Does that seem OK? Third case, I don't know what you thought, I don't have any ideas. But the key point is that all three of these dogs had lymphoma, OK?

And lymphoma is the topic, the fascinating disease that we're gonna talk about tonight. I'm gonna present my approach and hopefully an update on lymphoma, and I'm gonna point out where we can save some money in the treatment. And this is my first point then.

That you can put lymphoma on the differential diagnoses list for almost anything. But I would be particularly prioritising lymphoma as a differential if the tissue is enlarged or the tissue has a lymphoid function. And by that I mean things like liver, spleen, third eyelid have lymphoid functions.

OK. Let's start looking at diagnosis of lymphoma. Lymphoma looks like this.

OK? What you are looking at here is a visible clone of cells. They may be small lymphocytes, medium lymphocytes, or big lymphocytes.

They may or may not have morphological abnormalities, but the key thing is they all look the same. Now the main differential in the UK is a reactive lymph node. And this is a reactive lymph node where you've got a variety of shapes and sizes and morphologies of lymphocytes, because you've got different types of lymphocytes in the node at different stages of activation and different stages of maturity.

They're all kind of different things, doing different jobs. OK? So this is lymphoma.

And this isn't You can imagine lymphomas developing from any one of these lymphocytes. One of these lymphocytes could undergo a genetic change such that it keeps dividing and dividing and dividing and it will eventually crowd out the whole lymph node, resulting in the slide I just showed you here. OK?

So the difference is often quite easy. What do you think this is? Do you think they're all the same, or do you think they're different?

Now, if, if you were in a lecture hall with me, I'd be looking for answers, but you're saved from that humiliation now. I think these are all the same, OK, because I think we've got this one and I suppose we've got that, but all the others seem to be morphologically very, very similar. And what do you think this one is?

And my answer, I think this is a reactive lymph node because you've got big ones, you've got little ones and you've got kind of medium ones here as well. And what about this one? Well, this one's interesting because I think they look all the same.

I hope everyone can be persuaded to agree on that, but you can take this one step further because you've got mitosis going on, and this mitosis is particularly abnormal. When we learned about mitosis at school, who learned about mitosis involving the unequal division of one cell into 3 or 2.5?

Just doesn't happen. So an abnormal mitosis is a very strong feature of malignancy here, OK? Now I think we should always send slides to a clinical pathologist.

This isn't an area where I would like to save money. I didn't have to. That's because the diagnosis needs to be confirmed if we want to talk about guarded prognoses and cytotoxic drugs.

We want someone with a diploma in pathology signing off on things, ideally. Diagnosis can also be tricky. In a small proportion of lymphoma cases, I might guess 20-30%, possibly more in cats, it can be a difficult call.

And thirdly, As I'll go on to, perhaps we should be asking our pathologist for a bit more information than just lymphoma, yes or no. But I'd like to encourage you all to look at cytology in house because we want to avoid this. My first money saving tip, ladies and gentlemen, please don't spend 70 pounds or more of your client's money sending an aspirate of the morphologically normal salivary gland.

Labelled lymph node, OK. So cytology, make sure that you have a diagnostic sample and that the money spent in the lab test is justified and not wasted. The other point here is that I'm sure you'll agree with me when I say that the dogs who you like the most, belonging to the clients you want to help them most, will make a beeline to turn up desperately ill at 4 p.m.

On a Friday night before a bank holiday weekend. OK? And for these dogs who are very sick, you want to get them treated before Tuesday or Wednesday.

And so it really helps you to form a working diagnosis in a sick animal and get some interim treatment or some appropriate counselling of the client underway, rather than just leaving question marks and a progressively deteriorating animal for several days. And on a slightly geeky academic point, I think looking at cytology is really interesting because you can see the disease happening. And that's one of the reasons why I find oncology very, very interesting.

I'm going to show you a case now. This is Clyde, nine year old male neutered border collie is very well. But his owner has noticed lymph nodes the size of satsumas.

Stick a needle in it and the cytology comes back as reactive. OK? And they say there's suspicion for lymphoma here.

But not quite enough to call it. And the clinical pathologist recommend another test, histo, PA test or flow cytometry to confirm things, OK? So in this situation.

Who thinks we need to do another test, or who thinks we've got enough to call lymphoma at the moment? Obviously I can't hear what you're saying, but I'll have to just imagine on that one. You see, I don't think.

That it's essential in all circumstances to do a confirmatory test when the cytology is equivocal. Let me explain When a pathologist gets a slide from an enlarged lymph node, they'd be thinking about 4 types of processes in most cases. These are very broad categories, OK?

And when the cytologist is just describing lymphocytes. Actually, they've ruled out other types of lymphadenitis, and they've ruled out metastatic neoplasia, so it's more helpful than you might think. And where you have lymph nodes the size of satsumas.

I think the only differential. Would be lymphoma, reactive lymph nodes simply would not get that big. So looking at things in the greater context of the case, I think you can make a, a very confident clinical diagnosis even if pathology isn't completely supportive.

There's a brief digression here. When I when I graduated as a vet, this was my view on the hierarchy of diagnostic tests. I really underestimated the importance of my history and my clinic clinical exam.

I thought they didn't give very reliable information. I thought blood tests and imaging was a bit more reliable. But the pathology results, particularly histopathology, with the high court of diagnosis.

That's the way I viewed things. If the pathologist told me a diagnosis that didn't fit with what I thought from clinical exam and bloods and things, I would try to bend the details of the clinical exam and the history to fit. And as time has gone by, I've realised that wasn't perhaps quite right.

I now look at it like this. As powerful as pathology is, it's only one small piece of the jigsaw puzzle. And in some cases, it's a very, very small piece indeed, isn't it, with some of the stingy biopsies we tend to give these guys.

So no matter how great the pathology is, it's always limited in that it doesn't have access to all the other bits. So where your imager gives you an imaging diagnosis, the pathologist gives you pathology diagnoses, and it's our job as the clinician to put that all together. So I think we are the ones who should give the ultimate diagnosis.

But that's just a philosophical view. My key point here is that a definitive psychological diagnosis does not necessarily have to be achieved, providing you're confident. That cytology has excluded all the other clinically relevant differential diagnoses.

And in the UK we're lucky where cytology dominated by lymphocytes is usually lymphoma or reactive. Usually. Let's look at some more cases now.

This is Gibson, 12 year old little cocker, lovely dog. He had lymphoma, treated with a multi-agent, doxorubicin base induction protocol, and then when he relapsed, he had cock-based rescues, and he lived for 790 days. Low key, 10 year old bichon frise, same disease clinically as far as we're concerned.

Same treatment, more or less. Live for 135 days. This is Oscar, a 5 year old cross breed.

Multi-centric lymphoma, just treated with a COT protocol. Went into remission and stayed there, and I had the diagnosis confirmed, by the way. So he was put to sleep for something else 9 years later, he was cured.

And then we got Star again, 5 year old Bernie's mountain dog, we threw every drug in the book at this dog, and Star only lived for 29 days. And I've chosen these cases because they all had no concurrent diseases. They all had committed owners and they all had adequate funding, but there was something else responsible for the huge variety and survival we saw.

And this is the reason. Lymphoma is actually a potpourri of lots and lots of different types of diseases, and in a very important publication in 2011, a team of general pathologists, not specialist lymphoma pathologists, general veterinary pathologists from around the world, proved that the human classification of lymphoma, which gives you about 60 different types, would apply to dogs. OK.

So the, it's not contentious anymore. Lymphoma sounds like one disease, but it's actually loads. Now my point here.

We're talking about lymphoma on a budget today. And I hate to sound negative or cynical, but there are some types of lymphoid malignancies out there that are so nasty you may be justified in saying treatment may do more harm than good, or the benefit would not be outweighed. And I think these ones might be ones to consider acute lymphoid leukaemia, a third respond to treatment.

Those who respond live on average for 3 months. Primary GI lymphoma, that is where the just the gastrointestinal tract is affected, not the lymph nodes. Around half of them respond to treatment.

Those who respond live for a few months. Primary hepatosplenic lymphoma. Now these aren't the multicentric cases that involve the liver and spleen.

That's an important distinction. These are the cases that just involve the liver and the spleen. They're quite rare.

They usually present in fulminant liver failure, and the average survival, no matter what you do. Is one day And finally, we've got T cell lymphoblastic lymphoma. OK.

Not a normal high grade T cell, this is a special type. And in humans, it's now classified with the acute leukemias, and that might give you a clue as to how well these guys do. So particularly when cash is tight, it's very useful to be able to say to the owner stuff that's more specific about how long you expect their dog to live and also what the best treatment would be.

OK? And then they can justify finding the money or be at peace with not finding the money if needed. Fortunately and on a more positive note, these types of lymphoma are much more common and generally much more responsive to treatment.

Now within this green category here. You can still see a big variation in survival based on this subtype. If you're not familiar with looking at survival graphs, it's very easy.

You've got 100% of dogs up here, alive, and 0% of dogs alive here, against time. And it follows that dogs, diseases with the best survivals will have a curve that is up near 100 for longer. And those who have the poorest survivals will have a curve that gets down towards 0 sooner, OK?

So how do we find out what type of lymphoma we're dealing with? First, ask yourself, is this definitely a multicentric nodal lymphoma? Now multicentric sounds like many centres.

But in lymphoma, it tends to mean the habit is to refer to lymphoma where the bulk of the disease is in the peripheral lymph nodes. OK? So is this one a nodal or peripheral nodal multicentric type of case, or does it affect one of the specific organ systems?

Now, that may be as far as you need to go for the primary alimentary lymphoma, just in the guts or primary dermatological lymphoma just in the skin, you've got quite reliable survival data and treatments just from that, OK? But for the other, the more common multicentric nodal cases, the 85% of the cases, in other words. You'd need to take things further.

If you've diagnosed with histopathology, Just ask for immunohistochemistry and the classification to be applied. If you've diagnosed on cytology. Then, immuno phenotype with a test of your choice.

Find out whether it's T or B cell, and then have a good chat with a clinical pathologist. And you can get very, very close to the histoclassification this way. So I'm going to introduce 3 tests that can be used to confirm lymphoma.

And as I say, you don't have to do them in every case, but they're also the same tests that could tell you the type of lymphoma. So they are very useful if you can afford to do them. And I'm gonna run through them just now.

Number one is histopathology. And this asks the question, what is the diagnosis, OK? The only thing I want to say about histopathology really is please take out a whole lymph node if you can.

Now I'm no surgeon, but I've taken out popliteal or mandibular lymph nodes on the prep room table. It's not the hardest surgery. Please avoid the temptation to do true cuts.

And that's because lymph node has a very specific architecture. It has a germinal centre where the B cells tend to be, a paracortical zone where the T cells tend to be, and the capsule around the edge. And you'll need a sample of all of these to get a diagnosis.

If you're doing a true cut, you will miss a goodbye to the capsule. That's always the case. And you might do something like this where you've missed a germinal centre.

You might re-angle, take another one, and miss another germinal centre, and take a third just to make sure and you miss another germinal centre. So please don't true cut, you won't get a representative amount of the lymph node. The PA test is a really clever DNA test.

Now every cell in your body has the same set of genes. We know that, but lymphocytes are an exception because there's a little area in the DNA of every lymphocyte. That is unique to that lymphocyte.

And in the T cells that codes for the T cell receptor. In the B cell that codes for the immunoglobulin. OK?

When the lymphocyte encounters the antigen to which it's specific, it will start to clone itself to form an army to fight this antigen, and that clone of lymphocytes will often be at the level where the DNA can be detected with a PCR-based test. If you have benign inflammation, you'll have lots of antigens that the lymphocytes are responding to. Therefore, lots of clones and you get a polyclonal result.

If you get lymphoma, then it will all have originated from one lymphocyte and you get a monoclonal result. So par is really clever. And you can also run it from the slides that are already at the lab, even if they're stained.

OK, it's a PCR test and it's very robust like that. So, so that's all great. For me, the big bind is the sensitivity.

OK? It's got a most part test of a sensitivity in the range of about 70% in dogs lower in cats. And for you and me, that means that we need to use the PA test in 3 dogs with lymphoma, and we're gonna miss one of them.

And that's a big, big compromise for me. You also see that power is really developed for treating for diagnosing lymphoma. Is it lymphoma, yes or no.

It's just because you have to use separate primers for T cell or B cell that you can find out whether it's T cell or B cell. So it's not really designed for immuno phenotype in the lymphoma. Now, we also find that there's an increasing number of false positives if you're using the PAR test in situations where the index of suspicion of lymphoma is quite low.

OK? So if you can't really use it to exclude lymphoma from a lymph node. And as the par's getting better and better evaluated, we're finding the more it's used, the specificity, the number of false positive it gives, is going down a bit.

So it's not my first choice to test, but it can be useful, particularly if slides are already at the lab and you haven't got time or haven't got the possibility of going back and getting another sample. The test I favour though, and I use in most cases a lymphoma, is flow cytometry. And flow cytometry involves passing a line of cells, alongside a laser beam and measuring the light that's scattered from them.

The forward scattered light gives you the cell size. The side scattered light gives you the complexity. And just using size and complexity, you can identify what type of cell you've got quite accurately.

Where flow comes into its own though is that you can go one step further and attach labelled antigens to these lymphocytes. And that helps you further confirm what subtype of cells you're dealing with. If you look at this plot here.

You can tell the machine to ignore everything apart from the lymphocytes. And then you can attach antibodies to them, which tell you what antigens are on each lymphocyte. This is really, really powerful because before flow cytometry, the only thing we could do with things like this, flowy immunocytochemistry or immunohistochemistry.

And you can see the negative cells are kind of bluey grey and the positive cells are brown. What if you want to test for more than one antigen? You're gonna have the overlying of different colours, aren't you?

And it's not really possible to test whether you've got more than one antigen on the cell in a lot of cases. Let me ask you a question, how many antigens has a cell got? Answer is probably millions, I'll accept millions, I haven't counted, but you can't define a cell by one antigen alone.

The benefit of flow then is that you can look at these lymphocytes with any combination of different antigens on them, and you can find out exactly what subtype of lymphocytes you've got. So the bottom line is with flow cytometry, you can find out whether it's T cell or B cell. Very good for differentiating monomorphic lymphocyte populations, versus cancerous ones.

And you can get so much more. We're starting to notice now that some lymphomas express a random array of antigens. You might have T or B cell markers on the same cell.

You might have immature and maturous markers on the same cell when one of them should be lost. OK? So these aberrant immuno phenotypes are things we didn't know about until we started employing these tests and quite a few of these have different prognoses.

Part, the flow cytometry is also very, very powerful for telling you what type of T cell lymphoma you've got, and I'll, elaborate on this in a minute. It's probably better than histo for doing that. Flow can tell you, have you got an acute leukaemia versus stage 5 lymphoma.

Flow can tell you in a mediastinal mass, is it a thymoma or a lymphoma, and you don't need to take a biopsy or do surgery on the mass. So although the original classification was based on traditional histopathology, flow cytometry is rapidly overtaking. Histopathology is the best way to characterise lymphomas, and most oncologists would go to this if they can, particularly because it's done from fine needle aspirates.

You don't need to anaesthetize a dog or talk about surgical procedures. So I've got a summary slide here. And at the moment, histo, and immunohistochemistry is probably the best for giving you the diagnosis or T or B and the WHO subtype.

But flow cytometry is rapidly catching up, OK? I mean one type of lymphoma, the T zone lymphoma, it's in fact better. And flow tends to give us things like the new classifications, the aberrant immuno phenotypes, thymoma versus lymphoma, lymphoma versus leukaemia, OK?

It gives us so much more than we knew was possible. And power testing can certainly be useful if the other two aren't available, but it's it's limited by sensitivity. As I've just said, There are some labs who will claim that they've got a higher sensitivity than other labs, and I can't comment about specific cases.

They may have very, very accurate tests that are fantastic. But often when you increase the sensitivity of the test, you'll compromise on specificity. So it may not be the best situation.

May not be. Anyway, my key point here is finding out the type of lymphoma will allow you to counsel a client about the prognosis and the potential benefit of the treatment. Moving on.

We're gonna talk about treatment now, OK? This is Charlie, a 10 year old male neutered poodle cross. Multi-centric high grade B cell lymphoma.

So for you and me, this is the commonest type of multicentric lymphoma that will walk into our clinics. And you can see Charlie's fur here has taken this weird change. This is often what you see with poodles or the dogs who have to be stripped when they have chemotherapy.

Most dogs don't show coat changes, but poodles and the dogs who strip often do. OK. So what are the treatment options?

Just have a think for yourself. Well, the gold standard treatment here. Is the COP protocol.

OK. And with COC protocol and a rescue protocol when they come out of remission. The average survival of these guys is about 14 months, and a quarter are alive at 2 years.

It kind of goes like this, Vincristine like week 1, oral cyclophosphamide week 2. Vincristine week 3, doxorubicin week 4, week 5 off. And you repeat another 3 times.

OK. Prednisolone I tend to taper over 4 to 6 weeks. But the thing with the COP protocol is it's quite expensive.

It involves lots of drugs, lots of visits to the vets. It involves doxorubicin, which, let's face it, is a good but expensive drug. So if you're on a budget, could you use a cheaper COP protocol?

That's something I actually explored in this study that I published a few years ago, OK? Again, we've got these survival curves here, so the best ones will be up here and the worst ones will be down here. Now if you've got this type of lymphoma and you just give a COT protocol, you get the worst survival, the blue line.

This type of lymphoma, and you give a COP protocol, it's the red line, which is categorically better. Where it gets interesting though, is if you give the COP protocol. And the dog comes out of remission, and then you rescue with single agent doxorubicin.

You will get an identical or statistically similar survival to the CHOC protocol. OK? So you might think that treating with a less aggressive protocol to start with would encourage drug resistance and you'd undermine the chance of a better prognosis.

But this study tends to contradict that. It kind of says you're not undermining prognosis if you use a COP protocol, providing you're happy to rescue it with something else like doxorubicin later. OK?

That doesn't necessarily reduce the costs overall, but that does give a lot of flexibility to things. And the cop that I use is very simple. It's 8 weekly injections of vincristine.

Oral cyclophosphide every other day at home and prayed every every every other day with a cyclophosphamide. After the 8 weeks, and if they're in remission or maintained with oral chlorambil, methotrexate and prednisolone, very well tolerated, very cheap, very easy to do. There's another suggestion from this graph, though.

Who did the best, this purple line and who's that? Those he had chop and rescued with doxorubicin later. Those who had chop and rescued with nonoxorubicin didn't do half as well.

And this hints of the importance of doxorubicin in this disease. This disease really does respond well to doxorubicin in most cases. And in this graph, you can look at survival related to just the amount of doxorubicin you give.

So another cost saving option for this disease would be just give doxorubicin, scrapvilip pristine, scrap cyclophosphamide. Every 3 weeks, just give doxorubicin IV and clients may like it because it's spread out more, and particularly if you've got a nervous dog, they've got to face the vet once every 3 weeks rather than every week. Now if costs really are an issue.

You could use Lomustine orally and prednisolone. I don't like that as much. That's not a very hard hitting protocol.

You don't often tend to get the lymph nodes in full remission and it rarely works more than a few months. But it's probably double the time that prednisolone alone will get you. Though mustine, as I'll say in a minute, is a very unpredictable drug, and I'd prefer to avoid using it if possible.

So 0.4 then. Your doxorubicin-based CO protocols are the standard of care treatment for high grade B cell lymphomas.

But less hard hitting induction treatments can still be beneficial and may not undermine the prognosis, providing you're going to use a hard hitting doxorubicin-based treatment as a rescue later. Now we're gonna stick with Charlie a second, multicentric diffuselage B cell lymphoma, because I think he illustrates another good point. In this dog, we did have adequate funding and we treated him with a COP protocol.

As per the chop, there's no benefit in giving maintenance therapy after the induction, so we just left him. And he was in remission for 9 months. He then relapsed.

OK. And so we have a dog with relapse multicentric high grade B cell lymphoma. What would you like to treat him with now?

OK. And what we did We gave him chop or cop once again. When dogs relapse with lymphoma, particularly with the high grade B cell lymphoma.

It can often be because they're just undertreated. We, we innately think when dogs relapse that they've acquired drug resistance, and drug resistance means rescue protocols, and it's harder to get in remission, and the remissions don't last as long, and we have very serious chats with the owners, because that's how it is in human medicine, and that's how we kind of assumed it was in veterinary medicine. But something that's not a feature of a lot of human treatments is the kind of homoeopathic levels of doses that we're giving.

So it's not very well covered in the textbooks, and I thought I'd flag it now, that when a lot of lymphoma dogs relapse, it's not due to drug resistance, it's due to just under treatment, and we're happy undertreating them because it means they're healthy and have a normal life quality throughout their treatment. So, if the dog has not been on treatment for a good period of time. I think I'd try the treatment that we instituted at day one, say a test dose of incristine or cyclophosphamide, and see what happens.

And if the lymph nodes shrink down, I wouldn't talk about drug resistance, and I'd hope for an unchanged prognosis. It is more expensive to keep treating these guys though, and that can be a limiting factor, and I wish I had a, a cheaper alternative to that. So relapse does not have to mean rescue, and that's particularly the case in the high grade B cell lymphomas.

Now I've mentioned a lot of drugs. So this is a brief digression in my side box with the purple corners here. I'm just gonna go through some of the adverse effects, and if you want to use these, I'd encourage you to read around them in a bit more detail.

But all chemo drugs can cause gastrointestinal upsets or myelosuppression to varying degrees. And in poodle dogs or dogs you have to strip, it can also have fur effects. Vincristine is very easy on the bone marrow, and that's a good thing, that's useful.

Gastrointestinal signs are usually the limiting factor in dogs, particularly at the higher doses, and on rare occasions you can see peripheral neuropathy. But in general, particularly at the lower doses, it's an excellent drug. Cyclophosphamide goes well with vincristine, because its side effects are kind of opposite.

It very rarely upsets the gastrointestinal tract. It can cause more of a myelosuppression, but at the doses we use often not a problem. And it does have the horrible drug specific side effect of sterile cystitis.

And that's not a life threatening thing, but it can take ages to resolve and it can impact quality of life. Roxorubicin. I think the most important toxicity is gastrointestinal.

And apologies for the strength of my language there, but I hope it serves to remind you that it can cause severe gastrointestinal upsets, you know, necessitating hospitalisation of dogs, if you're not careful, for fluid therapy and supportive care. It can cause gastrointestinal blood loss which pushes the PCV down and things. So you have to be very, very careful dosing this drug, particularly if you've got a dog who looks at a bottle of Metacam and gets diarrhoea.

OK? We're all scared of the cardiotoxic effects of this drug and they're well published, and we're right to be scared of them, but they are cumulative. OK?

And the minimum toxic dose for an average heart is about double what we would use in the total CHOP protocol. So I think sometimes we worry about the cardiotoxic effects a bit too much. No.

Back to Clyde, who I showed you at the start. With flow cytometry, we got a diagnosis of multicentric, high grade T cell lymphoma. Now this is like the high grade B cell cases, but it's accelerated, OK?

They'll respond to treatment just as nicely to start with. Sadly, they'll develop drug resistance quicker. They'll come out of remission quicker and they'll take less time to become resistant to the second things you use.

So it's quite rare for one of these to relapse because they're undertreated, they often relapse because of resistance, I'm afraid. So how would you want to treat Clyde? OK.

Well, the first thing is that the T cell cases respond less well to doxorubicin, response rate about 50%. So, if costs are an issue, or even in view of the side effects of the drug, I'm not sure I'd want to use doxorubicin first line. OK.

Particularly with these studies here which shows that the T cell cases often respond better to lowmine-based protocols. So the protocol I favour and other ones are available are is the loop protocol. I think Christine day one.

Or a mustine day 8 nothing day 15. And then day 21, you start again. So this alongside prednisolone I suppose is the lop protocollo mastine vincristine Pred.

The plot protocol makes it a bit more complicated and that we give procarbazine every other day for the second two weeks. We tend to give pride all the way through all these 3 weeks. So it can get a bit complicated and it might not be for every owner just because it can be difficult to work out where you are in the protocol for an owner.

One of the benefits though is that this is the intravenous treatment and it involves seeing the dog every 3 weeks and you know, the rest is oral. So where you've got a shorter life expectancy, it can be quite nice to use an oral treatment. Procarbazine in recent years has been very expensive in the UK.

And so sometimes you could just stick to the bare bones of cristine lomustine. And that's easier, it's simpler, and it's cheaper. Or if costs are more of an issue, you could just go with Lomaine and Pred again like I mentioned before.

That's not quite as hard hitting. But it is an oral only treatment and it might be the cheaper option. And again, think of the COP protocol in these situations because the COP is a really good, well tolerated general treatment.

It can treat the T cell cases as well as the B cell cases. You're never gonna get the best remissions from this, but it's much better than nothing, and I would prefer to use this than Lomustine. Here's another side box here.

Why don't I like they mustine? Because it's unpredictably hepatotoxic. Hepatotoxicity is usually a cumulative thing, OK?

But in some dogs it's not. Some dogs it's idiosyncratic. You give one small dose and they get severe hepatitis.

So there's no dose of which you can say this low mustine will definitely be safe and definitely not cause a problem. It can also have annoying effects like very variable myelosuppression. Some dogs tolerate it very nicely, other dogs are very sensitive to it.

And procarbazine that I've just mentioned is more likely to cause gastrointestinal upsets, but generally quite a well tolerated thing. It's a. 6.

The T cell high grade lymphomas develop drug resistance quicker than the B cell cases and have shorter expected survival times. The treatments can oftentain more oral agents and be of lower stress to the owners. Here's another case.

This is Kirsten, 10 year old golden retriever, clinically well with huge peripheral lymph nodes, cytology confirmed lymphoma. PA test confirmed T cell immuno phenotype. On exam she had a very large spleen and she had circulating atypical lymphocytes.

So she's a T cell case, and what stage is she? Do you agree? Stage 5.

Stage 5 multicentric T cell lymphoma. You've got an owner asking you what's their prognosis, what would you say? Have a think.

Well actually Kirsten lived for 2.5 years, OK, and died of something else. So that brings us on to talk about staging a lymphoma.

Most dogs would be at least stage 3, generalised lymph node involvement, plus minus involvement of liver or spleen, plus minus involvement of blood or bone marrow or involvement of an extra nodal organ system like gastrointestinal tract, skin, brain, etc. OK? And you could, if you choose, do all these staging tests.

CBC, biochem, urinalysis, imaging, fine needle aspirates of liver and spleen, bone marrow aspirate, etc. But I don't often do this. Because staging a case of lymphoma is very unlikely to change the prognosis or change the treatment.

OK. The reason, one of the reasons is probably because most dogs are actually stage 5. This is a really good study where they got a load of stage 3 dogs and they did run PCR on the blood.

And in 80% of the stage 3 lymphomas, they found a par product floating around the bloodstream. So in other words, most dogs are stage 5. Remember, par is limited by sensitivity, so it's possibly more than 80% of these stage 3 in inverted commas, dogs in stage 5.

OK. And because I guess this is one of the reasons why the staging may be less effective. So if we're saving money, we could discuss this with the owner.

We could say that staging is unlikely to change the treatment or the prognosis. So we could consider skipping it. Now we shouldn't take that decision lightly, because staging is useful, just not the way you might think.

If I'm, if I've got a 10 year old golden retriever who I want to start on chemo, I'd like to know about the splenic mass that's about to burst or the adrenal mass that's eating into the vena cava, OK? You might look a bit silly if you start talking about treatments for lymphoma and something else kills the dog first. And on a practical level, it would be nice to know if we got things like pancreatitis, Cushing's, hypothyroidism or other diseases that need optimising in their management.

Also, lymphoma may come out of remission in one part of the body only. You have a process of divergent evolution going on as described by Charles Darwin. OK?

So you might have drug resistance just popping up in one lymph node in the abdomen when the islands of lymphoma within the peripheral lymph nodes stay under control. So, how would we know if the cancer is in remission when the induction treatment finishes, if we're not looking at the dog holistically? And as a small point, sometimes dogs with a very large burden of lymphoma can become poorly as you start treatment.

This is big news in human medicine, tummolysis syndrome, but because of the differences in purine metabolism between dogs and people. Tumorlysis syndrome is very, very rarely encountered in dogs. It's more an issue of inflammation as the cells die, OK?

So this is a less important point, point 3. But I hope to have given you a potential route to which we could save a lot of money with the staging here. Staging rarely affects treatment or prognosis but is useful for detecting concurrent disease and monitoring response.

Now Kirsten's story doesn't end here. Lived for 2.5 years, died of something else, and was treated only with chlorambuil and red.

Why is this? That's because she had another type of lymphoma. This again is something that we've discovered with flow cytometry, that there's two types of T cell lymphoma commonly encountered.

One as CD4. And low levels of MHC2. And that's the one I just discussed, the aggressive clinical course, poor survival.

But where these markers are polarised without CD4 and with high MIC Class 2, you get a very, very, non-aggressive behaviour, and the survival curves look like this. This is Kirsten's lymphoma, and this is T cell, T-zone lymphoma, and indolent lymphoma. OK.

Very, very good disease to find. So, T zone lymphoma, you can get a good idea of it on histo, but flow cytometry has got the diagnosis of this thing nailed because of the ability to detect multiple antigens on the same cell. And And it typically involves peripheral lymph nodes usually identified at a very late stage, and you think why is it identified at a late stage?

Because it often progresses in a very indolent and harmless way. So this is the most common type of the indolent lymphomas. And now we're better at diagnosing lymphoma, we're finding more and more of these.

So you've got T zone, marginal zone, mantle zone, follicular. These could be the most common. How do we treat these?

I'm afraid we don't know, OK? You could choose to do nothing. Particularly if you find the disease at a low stage, that is just one lymph node and it's nowhere else.

If you find it at a low stage, you could consider just monitoring it, because often, they will take such a long time to progress that treatment isn't justified. OK? You could consider surgery for these or radiation therapy.

A lot of cases are detected at a later stage where they involve the blood and enlarged spleen and lymph nodes everywhere, and surgery, radiation or just, you know, it's not really appropriate. And just monitoring them also you may feel uncomfortable with if there's such a large burden of disease. So often we treat with chlorambuil and Pred or if that doesn't work, clomustine.

But we really need prospective trials on the treatment for these diseases to say which treatment is best. And at the moment I'm afraid we don't have that. So if you get one of these, they're good diagnosis to have, please discuss it with a friendly oncologist and we'll need to come up with the most appropriate plan for that case.

It may be just doing nothing. Another point with these, if you find it and you think it's at a low stage, it's probably worth staging. And this is one exception, I suppose, where staging may change the treatment, or possibly the prognosis that we give, depending on where is the timeline we find them.

The other thing is that when you start treating these with drugs, often the lymph nodes don't shrink down to nothing, they just shrink down kind of 50% or so. And it can often take weeks or months to do that. That's because these cells are dividing at such a slow rate, it does take quite a lot of time for the lethal effects of drugs to be realised.

So it's a case by case basis. 0.8.

Then indolent lymphomas are fantastic diseases to recognise, and many do not need treatment until very advanced. And my last case for you tonight. This is a very sick dog, another golden retriever, I'm afraid.

Susie, six year old female neutered, presented dyspneic, pleural effusion, mediastinal mass, hypercalcemic, OK. Now I was called to look at this dog when she was oxygen dependent in ICU and I was also paged alongside an anaesthetist. And the idea was to anaesthetize the dog and take a true cut biopsy of the mediastinal mass.

Now, it's easy to miss in a desperately sick animal. But I found her pre-scap lymph nodes were actually enlarged. I stuck a needle in them, we got the diagnosis of lymphoma, and we didn't need to anaesthetize her.

So it can be hard. But you know, when the pressure's on, please don't forget palpation of lymph nodes, because in this case we were able to save a lot of money in an unnecessary procedure by FNA in the lymph node. And you'll see this, this is what we got with the aberrant mitosis, all the cells looking the same.

This is an aggressive lymphoma. This is the lymphoblastic lymphoma. OK.

And I did mention this at the start. Lymphoblastic lymphomas are now classed in human medicine alongside the acute leukemias. These are really, really aggressive diseases.

It's kind of like an acute leukaemia that occurs in the lymph nodes for some reason ignoring the bone marrow. But my point with this one is if you've got a desperately sick dog, OK, you can't breathe and you need to do something right now, what do you give? Just have a think about that.

Well, the easiest answer is what not to give, because every single chemo drug, whether it's high dose doxorubicin or low dose cyclophosphamide, all of these things are slow burning treatments. So if you're at 4 p.m.

On a Friday night, don't expect to get the dog out of oxygen by about Tuesday, Wednesday at the very earliest if you're giving the chemo drugs, pretty much all of them. OK? The best drug we can give, if it's possible, is asparaginase.

And that's not a cytotoxic chemo drug. It's got more in common with penicillin. It's an enzyme produced by E.

Coli and that depletes the body of asparagine. As it happens, nearly all cancerous lymphocytes can't produce asparagine. But all the other cells in your body can, OK?

So it's a very specific treatment and it can be incredibly fast. It's the fastest drug at knocking down a lymphoma burden and making the dog feel better sooner. So, if you haven't got asparaggenase, steroids.

Steroids are much, much quicker than chemo drugs, and they're cheap, and we all understand them, OK? Not quite as fast as asparaginase, but it's still a budget option for you. So if you've got one of these dogs, please don't be frantic about trying to refer it.

I just may discuss it with an oncologist if possible, and then to get the dog out of the woods, dexamethasone is often all you need. So with Suzie we gave asparaginase and dexamethasone together, gave him Christine a couple of days later and transitioned to a plot protocol. Did quite well actually, got to 8 weeks, relapsed.

Was then put to sleep and I wish we could do better for these guys. So emergency treatment of the higher intermediate grade lymphomas. Consider asparaggenase, if not, give dexamethasone.

Bear in mind this is more ulcerogenic than Pred. So please provide gastro protection and start pred 48 hours later. You also don't need comedy doses of dexamethasone 0.3 mg per gig is usually fine.

So some adverse effects again, or only one. Asparaggenase is not cytotoxic, you don't need to baron nurse the dog, but it can cause hypersensitivity because you're injecting a foreign enzyme. Very unlikely to be the problem after the first dose, but we need to provide antihistamines or steroids to protect the dog.

On rare occasions in people and dogs it's been associated with development of pancreatitis. Rare occasions. And again, rare in dogs would be the tumour lysis effect by killing so many cells all at once.

They are the body's own cells, and stuff that should remain inside the cell gets outside the cell. OK? It's the same reason why a down cow dies because of the release of things like potassium and calcium that should stay within the cells all getting released in one big burst.

Very rare to see problems with that in a dog with lymphoma. OK. So if you need to treat lymphoma as an emergency, don't consider chemo.

Steroids is probably the cheapest option. And finally, I'll talk briefly about rescue protocols, OK? The most important question you can ask is, are they definitely resistant to what we used before?

Or are they just undertreated, particularly your high grade B cells? And I have the rule if a dog's been off treatment for about 6 weeks, it's worth giving a test dose of whatever you used first to get them in remission again. See if that works.

If not, I'd go to a rescue. If they relapse while you're in the middle of a protocol, then you have to assume they're resistant and you use something else. Second question is, what have they had so far?

If they haven't had doxorubicin, this would be a good choice for a rescue. Or if they haven't had Lemustine, you could give Lemustine, OK? And other options we're getting more expensive now.

The DMAC protocol involves dexamethasone, melphalan, actinomycin D insidearabine. And you need to be quite experienced in cytotoxic use to give this. It's not for the faint hearted.

OK. Often the dogs get gastrointestinal upsets, and by this stage, they may have had a lot of other chemo drugs. The bone marrow's a bit tired, and you give quite a hard hitting treatment as well, and you can get borderline low platelets and borderline low neutrophils very, very commonly.

Asparagina might be a rescue, but sadly it's expensive. You could perhaps combine it with lowmastine, that works well. Or there's Tanavia CA1 which has conditional licencing in the states for the treatment of lymphoma in dogs.

I didn't talk about it much on this session because it is very expensive sadly, but if you're interested in using it, you can find all the information online and you can import it on a named patient basis from VETDC Part of Elanco now. So as I said, DMAC often causes GI upsets, and often causes things like thrombocytopenia. Tannovia can cause pulmonary fibrosis.

Again, that's a cumulative thing. And that's another potential side effect. So where drug resistance exists, remissions will be about 50% in length and harder to achieve than those seen originally.

And in summary, you'll be pleased to hear. I think lymphoma is a fascinating group of diseases. Many dogs now benefit from subtype specific treatments and enjoy extended survival.

And clients will often thank you for being quite specific about how long you expect their dog to go on and what is the best treatment, rather than saying, oh well, let's see what happens. To diagnose lymphoma, you may not necessarily need confirmatory tests because the the last stage in their diagnosis is the clinician signing off on things. If you think there are no other differentials clinically, then that's good for me.

As I said, subtyping will allow you to determine the best benefit of treatment and select the best treatment. And these are also the tests that could confirm the diagnosis of lymphoma, histo, par, or flow. So consider for the whole package of inflammation it may bring.

Don't just go to the one that the pathologist recommends to confirm the diagnosis. You want to do more than just confirm the diagnosis. If funds don't allow, consider COP protocol for any high grade lymphoma.

OK. The Mustine prayed I think is poorer, but it's better than nothing. You could consider no treatment for early stage indolent lymphomas that are very healthy.

Consider steroids and if possible, asparaginase if funds will allow, in the emergency setting. Please remember that relapse does not have to mean drug resistance and rescue, especially in the B cell cases. And if you get a case and you've got questions, I'd be more than happy to discuss it with you, and I'm sure other oncology specialists would too.

Now, if you're interested in learning more, Butty Villiers, er Queen of flow cytometry. Did an excellent review of diagnostics for lymphoma in in practise earlier this year, and I think that was probably the most complicated stuff of the talk tonight. Also, if you're interested in cytology, please look at the veterinary cytology Facebook page, if you're interested in oncology, look at the ESON page here, we'd love to have you as members.

I'd like to acknowledge my colleagues who tolerate me every day. I have to give a big shout out to all the people bearing the true brunt of this crisis and a huge thank you to all these key workers from the bottom of my heart. And thank you to you guys for giving up a Thursday evening to listen to me.

I'll do my best to take any questions now, but if you've got any others or any case you'd like to discuss, please feel free to email me there. So, thank you ever so much. Owen, thank you.

I, for those who know me, I'm not often speechless, but wow, that was absolutely fantastic. So a huge thanks to you for giving up your time and for making such a clear and concise presentation for us. I, yeah, as I promised everybody in the beginning, this was going to be a wonderful talk and it way surpassed that.

So thank you, Owen. No, thank you for your kind words. We haven't had any questions come through.

We've had lots of comments that I've been inundated with about what a fantastic webinar and how fantastic the whole presentation was. They, yeah, as Anthony always says, if we were in an auditorium, there would be thunderous applause. So thank you.

We do have a couple of questions coming through now in amongst all the thank yous. Elijah asked, what would you recommend if subtyping is not available? I think that's a really good question.

Thank you for asking. I would probably go with cop, if you could. For again, I think they.

Drugs we have good doses for. It's a well tried and tested treatment. And also the, what we've shown it certainly in the B cell cases that you're not undermining the prognosis if you want to rescue them with something a bit more hard hitting later on.

The, on a different note, the Vincristine is not considered to be cumulative in dogs, and that's quite important. For some dogs, you could keep giving it if needed. And the little cocker spaniel, Gibson, I showed you at the start, in the end we ended up giving him a vincristine injection every 2 weeks and did that for a couple of years because it was the only thing that kept him in remission and the cheapest option.

And with a lot of chemo drugs, particularly doxorubicin, Lomustine, things like that, there's a limit to the amount you can give in a dog's lifetime. So coppaincristine, which is really well tried and tested, really useful and robust. And also the cyclophosphamide, despite its category of drugs being a cumulative category.

As it happens, it's very easy on the bone marrow, and particularly so in the platelets. So, in the real world, you don't tend to get cumulative effects of cyclophosphamide too. So I think the cop is the safest, a good general treatment for all types of high grade lymphoma.

Fantastic. Owen, I'm afraid I could sit here and listen to you all night, but we have run out of time. So once again, thank you for your time tonight and to all the members that attended tonight.

I'm sure you are not disappointed and would love to sit through this and pick up and listen to Owen's fantastic information. So thank you to everybody, to my controller in the background, Dawn, as always, thank you for making everything happen smoothly and from myself, Bruce Stevenson, it's good night.