And for those of you who've been to my lectures before, you'll know that I like to do things, in a very practical way, kind of give you top tips that you can actually use in real life. So, you know, hopefully there'll be something for everybody here. Obviously, anaemia is a subject that's really close to my heart.
It's a very common problem that I see within my oncological patients. But it's also been something that I've studied for a long time when I did my work in transfusion medicine and so forth during my residency. So, I hope that you enjoyed today's talk.
So first of all, I just want to remind everybody what the definition of anaemia is and and this was a hot topic when we had a pan-European group looking at how to teach clinical pathology across Europe, because everyone had different. Ideas of what the definition of anaemia was. And in the end, we came to the conclusion it was all of these things.
It was a decrease in red cell count, a decrease in haemoglobin, which is what humans tend to refer as anaemia, in human medicine, or it's a reduction in the pack cell volume or the hematocrit. And the key thing is here that the presenting signs are pretty much always the same, OK? They, they're gonna come in, with signs of a membrane pallor, and that's gonna be a fairly consistent finding in anaemia.
But your CRT is going to be normal. But the way they come into your practise or your consulting room is quite variable. Some will present with severe lethargy, severe exercise intolerance.
Some might even be collapsed and absolutely flat out and have maybe poor stress tolerance. And a great example of this was, many years ago now, I was taking some blood from a chemo patient and a routine check for chemotherapy. And I thought, yeah, it's membranes look a little bit pale.
And we walked it to the area we're gonna take the blood from. Took some blood and literally within a matter of seconds after trying to take the blood, the dog became really, really collapsed. It was this massive, mas stiff and we had to then pick it up and run down the corridor, and get it into the ICU to get it resuscitated.
And it was the stress of that procedure. So you can see problems here with stress tolerance as well. But they can also be completely asymptomatic.
And to balance that, I had a patient when I was doing my residency in Edinburgh, it was in the older hospital which had a very, very big staircase all the way up to the top, and this dog had come all the way up the stairs, and it was totally, totally fine. It had no signs of its anaemia whatsoever. OK, but you know what, it's PCV was 15%.
I was absolutely gobsmacked because it it got up those stairs, it was showing really no clinical signs whatsoever. So it's really important to remember that the presenting signs may be quite different, but the clinical signs of this pale membrane with a normal CRT are are very consistent in anaemia. The other symptoms really reflect the body's changes to try and get oxygen around the body.
So these are kind of more secondary changes, the tachycardia, the systolic murmur that you'll get because of the change in flow with this more kind of runny blood. I like to think of it. It's sort of watery blood because of the lack of red cells.
In cats, you might hear gallop sounds. And of course, the murmur and the gallop sounds often push people towards thinking, could this be heart disease? But remember in heart disease, you may actually see a failure of the CRT, so the CRT might start to become prolonged, it won't be brisk, whereas in anaemia they often are quite brisk because of this tachycardia, and this attempt by the body to try and get blood to go round all the peripheral areas.
They often become tachypneic and again, this is because the body's saying, give me oxygen, I need to get more oxygen in that the body's response is to breathe faster. OK, so it's pumping blood faster, it's breathing faster. But it isn't gonna make any difference cos there's just not enough red cells to transport the oxygen around the body.
You may see jaundice, that might occur if you've got a severe destruction of red cells, so a hemolytic process, but not always. So if you do see jaundice, OK, you need to look underneath the jaundice. And by that I mean, when you have a very yellow mucous membrane, you need to look and see, is the underlying colour pink?
Or pale as in this picture here. So you can see this is a very pale mucous membrane, and this was actually this dog that did not have clinical signs, it, it came up. Owner said, a little bit lethargic, but it came up this massive great flight of stairs, whereas this one didn't have such a bad anaemia, but it was collapsed.
And the reason for this different presenting situation is because chronic anaemia is really well tolerated, because there's time for the body to adjust to that low oxygenation. Whereas in a very acute anaemia, where the, the PCV falls away very, very quickly, the body can't adjust, and so it really starts to struggle. So the key here is that we can't define how badly affected the body is by looking at the severity of the anaemia, the PCB.
So Traditionally, we have always classified anaemia into different groups. And this is kind of why I like anaemia, because it's a really straightforward process which divides, if you like, into the two sides. OK?
So we can say, as soon as we divide it, and then we divide it again. And I love those kind of differentials. I, I, I like it when you can take something and you can separate out different sections, because that makes it much, much easier to work out what's happening.
So our first split is, is it regenerative? In other words, it's the bone marrow producing new red cells, or is it non-regenerative? OK.
And within the regenerative section, we'd expect to see things like hemorrhagic in this, as in this picture here, where we've got dramatic blood loss. Would normally result in a regenerative anaemia. And in hemolysis, where the red cells are being destroyed and all the contents of those red cells are available for recycling, they will often be strongly regenerative.
And then on the other side, we've got a, a, a typical, very common example of a non-regenerative anaemia, which is a cat with chronic renal failure. And you can see that immediately, just looking at these images, we can start to understand why history and our clinical examination will help us identify possible causes of the anaemia. So we need to think about the way the animal's presenting, because that may point us in one direction or the other.
So once we've kind of grouped it into non-regenerative versus regenerative, we've then got a, a fairly defined list of problems which can give us a non-regenerative anaemia. OK? And the key thing here is you can look down this list, you can see quite easily that there are relatively quick tests you can do.
There's also gonna be other clinical signs associated with some of these. So the cat with chronic renal failure, for example, rarely presents with anaemia as its primary problem. It's going to present with other things first, like it's PUPD, it's gonna have weight loss potentially, it might have gastrointestinal symptoms.
So we're going to have other symptoms associated with many of these problems. But it is worth remembering that anaemia of, of chronic or inflammatory disease is the most common cause of anaemia in all animals. And they've changed the name since I first learned about it.
They used to call it anaemia of chronic disease. But that kind of sent out the wrong message because it started to make you think, well, how long, how chronic is chronic? And it, it really is about the inflammation and the changes that occur when you are in a disease process.
So, it's really important to understand that that's gonna be a really common thing, but it shouldn't be that severe. OK? So, but it might be a factor in some of these other diseases as well.
So when you look at chronic renal failure, there may be a factor there. It may be a factor in, in liver disease, for example. So we need to kind of go down this list and just make sure that we've ruled things out, both in terms of clinical signs and in terms of tests that we do.
On the regenerative side, we've got haemorrhage, so blood loss, that could be internal blood loss or external blood loss, and hemolysis. And when we look at hemolysis, we tend to define it into an immune-mediated process of hemolysis and a non-immune-mediated process. So, as I've kind of touched on, history can really help you.
So, when you've got this presenting thing that looks like an anaemia and the, the patient looks like it might be anaemic, you need to think about the questions you want to ask within your history. So it's important to ask all the questions about general health, and particularly thinking about any symptoms of other disease, such as kidney problems, liver issues, any endocrine disorders. If you're thinking about blood loss, think about the ways in which blood could be lost.
OK. So, where can blood go from the body? Well, a common one might be the urinary tract, if you see hematuria, for example, or vomiting.
But we also need to think about. Parasites within the gastrointestinal tract, particularly things like hookworm, can cause severe anemias, and the respiratory system. It's important to remember that if an animal is coughing and coughing up blood or has a, a tumour in the throat region, and that is bleeding, that may look like gastrointestinal blood loss, because as they swallow that blood down and it becomes more like a melina problem, you need to be able to differentiate, is this a gastrointestinal problem or is this a respiratory problem?
We also need to think about whether there's been any recent trauma or any surgical intervention because that obviously is gonna result in some blood loss and potentially contribute to anaemia or be the primary cause. We can also think about causes of hemolysis, and we're gonna touch a little bit more on those later in the talk. But thinking about when was it last vaccinated, because we know vaccination has an association with an immune-mediated, hemolytic anaemia in the dog.
Has the pet travelled somewhere? Could it be leishmaniasis, ehrlichiosis, and so forth? Has it been on any current medications, both in terms of, is that a, a cause of a hemolytic process as a sort of secondary process, or is there anything there that that's kind of causing it problems?
Has the owner mistakenly given it something else? Has it had access to any toxins there as well? In cats, we need to know, are they indoor cats or outdoor cats, primarily for this association with FELV and FIV.
So we need to know what they're kind of doing, and whether there's any risk of potential infectious process there. And remember as well that the The most common reason for hemolysis in the cat is mycoplasma species. So they can get infected by other cats and and transmission there.
And there is, you know, increasing evidence of of different mechanisms by which they can be infected. So when you're in practise and you need, you see a patient, you're pretty sure it's anaemic, it's got pelmucous membranes, but it's CRT it's normal, and it's tachycardic, it's tachypneic. What are we gonna do?
How are we going to investigate it? Well, I know for many of you, you can go and go straight to your haematology, analyse that and run a blood, and that is absolutely great. But there are situations where that is just not practical, OK?
Even in in our country in the UK, there are still practises who don't have immediate access to haematology analyzer. And obviously, we have to think on a more worldwide basis that there are a lot of practises in other countries that may not have that facility. But we can still actually do a lot with not very much, which is a great thing about anaemia.
So what we want to do, is have a look at the PCB and hematocrit. We want to know what the total protein is. We want to think about doing a slide of glutination test, and we want to do a blood smear, and ideally, some way of assessing the reticular cys.
So that's going to tell us if it's regenerative or not. So we're gonna go through these in a little bit more detail. The first one, I said, was looking at that PCV and hematocrit.
And I tend to use those terms interchangeably, but that's not strictly correct because a hematocrit is a calculated parameter. OK. So, it's calculated using a machine, and it counts the number of red cells, and it counts the size of the red cells, and then it adds it all together and creates a hematocrit.
And I always think this is quite ironic, because we actually use a microhematocrit centrifuge, not to look at hematocrit, but to look at PCV. You know, one of those crazy things. Why is that?
Very odd, and a little confusing, I have to say. So, what this will tell us is the severity of the anaemia, because remember I said earlier that you can't define the severity of the anaemia based on the clinical presentation of the animal. OK, because you've got that dog that collapsed when it was getting a blood sample, and you've got the other one who made it up a massive, massive flight of stairs and showed basically no clinical signs, despite the fact it had a much worse anaemia.
It's also really important to remember when we're assessing severity of anaemia, that cats start with a lower PCV. OK, so they start lower than dogs do. And that's because of their red cell physiology.
They're very good at holding onto oxygen until it reaches very low tensions. And so that means they don't need to have quite as many red cells in the first place. And that's why they are also much better at tolerating anaemia than dogs are.
So, what you'll find is cats. I mean, I always think I think cats are really sensible anyway. So when the cat starts to feel the burn from the anaemia, what does it do?
It just sleeps more. It doesn't go running around. Whereas daft dogs, what do they do?
They all go running around, they fall over, they bounce back up again, and they run around a bit more, and then they fall over again. They're really dumb. They don't learn.
Cats are really brilliant at learning, so they tend to present much further on in their anaemia. OK? So we can see cats right down at the sort of 10%, and the owner really didn't know very much about it at all.
OK? So it's really worth bearing it in mind that when you look at the severity of anaemia in a cat, it will be much more severe for much less clinical signs. The other thing that we can do when we're looking at a, a microhematocrit centrifuge to look at our, PCV, is we can also look at plasma colour.
And on the right-hand side here, we've got examples of the kind of things you might expect to see. So, if your plasma colour is completely normal, it should be a nice, clear colour. And that would be the situation in non-regenerative anemias, very common to see that.
If you're seeing a very yellow plasma colour, then that obviously is consistent with jaundice, and that might be due to hemolysis, but you also need to bear in mind that it could be due to liver disease and that anaemia could be secondary to liver disease. And then lastly, that one, the, the, the sort of syringe full there on the right-hand side, that is severe hemolysis. Now, that can sometimes happen if you've sucked your blood a little bit too fast when you're taking your samples.
So, or if someone's been silly and, and squirted it through the, the needle into the tube. So you just need to kind of take a moment to think, is that right? Does that fit with the clinical picture?
OK. So, always, any results you get as a vet, does it fit the clinical picture? So what about total protein?
Well, total protein is a really a way of assessing whether the whole blood is being lost, because obviously, the blood doesn't just contain red cells, the blood contains plasma, and the plasma contains protein. And you tend to find that the protein can be restored a bit faster than the red cells. So if you pick up, a blood loss in a fairly early stage, you may find that you're getting lower levels of protein because the blood has been lost.
But obviously in hemolytics and non-regeneratives, there is no loss of whole blood. It's a failure of the red cells to be made, or it's a loss specifically of red cells. So in that situation, you'd expect it to be normal.
OK. That doesn't mean it's always going to be normal in those situations, because there could be another reason. OK?
So it's really important to just remember, does this puzzle fit the picture that I'm building, or does it not? And try and keep an open mind. And the other key thing is, because the protein levels will normalise faster than the anaemia, you need to remember that just having a normal result doesn't rule out blood loss.
It doesn't mean it's definitely not blood loss, OK? But it can just help you. And it's a perfectly reasonable thing to look at total protein using a refractometer.
You just need to make sure you've got a refractometer that has a protein scale on it. So my next initial test is the slider glutination test, and this is another super, super easy one. So all we're doing here is we're trying to see if by adding some saline to the blood, we can disperse any clumping caused by Ruo formation.
OK? And if you've forgotten what Ruo formation is, it's the kind of effect that, where red cells stack up next to each other. It tends To be more common when you've got very high protein levels.
So if you've got hyperglobu anaemic patient, for example, it's more common, and it's really super common in cats. OK. So if you put a drop of cat blood onto a slide and you see a bit of lumping, no big, no biggie.
That's, that's possibly normal for that cat. But then you add the two drops of saline to that, and then you kind of just give it a little swir about. And you're gonna have have a look at it, you're gonna have a look grossly, and you can see on this, picture on the left hand side here, we've got normal, normal blood, not a glutinating.
And then we've got a glutinating blood on the top here. And that's a little bit of a close up picture of a positive agglutination. And you can see straight away, it creates this kind of granular appearance.
And that means there's something abnormal sticking the red cells together. Even if it looks normal like this, you still should have a look under the microscope. And this is a bit of a cheat because this is a slide, this is an air dried smear showing lumping.
But what you can do is take this wet slide and actually put it under the microscope, and you'll see the red cells a little bit better. It doesn't need to be on a really high power, just under the microscope, so you can see them a little bit more clearly. Excuse me.
So if they're clumping, that's a positive slide glutination test, and that tells you immediately that you have an immune mediated process sticking the red cells together. OK, so antibodies clumping the red cells together. So what about a blood smear?
I think a blood smear is probably one of the most underutilised tools now. And it's a lot of it is because we have the machinery that allows us to do the differential count and get the platelet count and all of this without looking at a blood smear. OK?
But blood smears are really, really useful. Because even in your in-house analyzer, it's not necessarily going to pick up things about red cell morphology. OK?
So remember to make your smear as soon as possible after you've collected the sample and air dry it, OK? You need to air dry it nice and quickly so that you don't get changes in morphology. And a smear could tell us so much.
You know, it's such a shame people don't use it more because I see, you know, differential counts that are really weird and I've got a really high monocytosis. And thinking, well, a smear would tell me, is that an abnormal cell or is that a real monocytosis? OK?
Or you get a low platelet count. Great thing to look at. Easy to do a platelet count.
And I've just shown you some, some images down here to show you some of the things you can see. This picture here has got spherocytes, OK? And those of you who've listened to my lectures before will know I like to call them errocytes, because they're very cool, OK?
And then on the right-hand side, We have schistocytes, and they're very different. Remember that they occur because the red cells have been chopped up. And my favourite way to remember the difference between the sphrocyte and the schistocyte is to think about the mark of Zorro, OK?
So the big sword goes schistocyte. And that tells you immediately that a schistocyte is something that's been broken up. And I think you can see immediately what's going on there.
In the slide in the middle, we've got variation in in red cell size. And this is, this one here is, is almost certainly a reticular site. We don't have the stain here to say definitely that it is, but it's a large cell and it's polychromatic.
So it's much darker staining than the other ones. So it's almost certainly a reticular site. So that leaves me really nicely onto reticular sites.
And this is gonna be the way that we are going to define whether it's a regenerative anaemia or a non-regenerative anaemia. OK? And what we're basically doing is we're doing, looking at a smear, OK?
And it's, if you're doing this yourself, as opposed to using a machine, remember that you need, you need to use a new methylene blue stain. And that new methylene blue stain is called a supra vital stain. So what that means is that it the cells have to be alive for the stain to come in.
So there's no point putting the stain on an air dried smear. OK? This is one where you have to add the stain to the blood when it's still liquid, and then smear it.
So it's kind of the opposite way around. Instead of smear and stain, it's stain and smear. OK?
And the big thing in cats is they have two forms of reticular sites. So if you are doing this yourself, you need to remember that they have these aggregate reticular sites, which are shown in the picture up here, and they are big clumps of this leftover, nuclear material that that's nuclear remnants that we're effectively seeing. And they, that's the ones we have to count.
There are some really nice little ones here with occasional little bits in. They are called punctate reticular sites, and they've probably been hanging about for 3 or 4 days by now. So they don't reflect what's going on currently in the bone marrow.
So we need to make sure that we're only counting the ones that are current, if you like, current production. And then we can use that count to calculate the entire number of reticular sites that exist. And then we can decide if it's appropriate or not.
OK? So, what you can see here is that the, the, there are different kind of categories of regeneration. And when you look at your results that come out of an analyzer, OK, it's going to give You a reticular site count.
So here's the percentage. So this is saying 1.6% of the 1 1000 red cells that you might count are reticular sites.
And then it calculates that. It takes the red cell count up here, and it calculates out how many in real terms that actually is in terms of reticular sites, OK? And then it puts it on this little bar here.
All right? And you might go, well, that's normal. That's fine.
Well, is it normal? Because what you're expecting is if you've got quite a marked anaemia, you're expecting to have lots of reticular cys, cos that's what the body should be doing, isn't it? It's supposed to be producing red cells.
So you can't just go, oh, it's in the normal range. OK, so you can't just go, it's 11, and my PCV was 10%. No, that's not good.
OK. So you need to take into account the severity of the anaemia. You can't just look at the count itself.
OK, so we can have these figures that tell us. This is a marked regenerative response. Great.
You know, 200. Fabulous, big regenerative response. Is that appropriate for the severity of the anaemia?
So if you only have a very slight response, if your anaemia is very mild, then that might be OK. All right? So it's really important to look at the severity of the anaemia and put this all into that context.
So once we've done these basic tests, we can narrow if you like, down to our specific areas that we're working with. So we've got our non-regenerative where we're going to see very few or no reticular sites, kind of an inappropriately low number of reticular sites. Our protein, our total protein will be normal because it's not gone anywhere.
This is a failure of response. But it is worth remembering that the reticular site count takes a wee while to come in. OK?
So, if, for example, I've performed surgery, and I say me performing surgery, because I don't do surgery anymore. So if I perform surgery, this would be the outcome, which is the dog has lost a lot of blood. OK?
I used to be very paranoid, when I did do surgery, I was always going, Oh my God, there's blood. And coming up with the tiniest little dot on my swab, and all the other vets would be like, Claire, that's the Tiniest little dot. But that's why I'm a medicine clinician, not a surgeon.
OK? Because it would be a total disaster if I was a surgeon, because I'd be so panicky all the time. I would never, ever get anything done.
So, anyway, back to the reticular side. If I did my surgery and I'd done a bad job, which is what I'd probably expect to do, I would see bleeding at this point, OK? But I wouldn't necessarily see the reticular.
The site counts start to rise till about day 4 or 5. OK? So it's really important to bear that in mind.
If you've got a dog that's collapsed with collapsed with a splenic, you know, rupture because of Hemangiosarcoma, you're not necessarily going to see that reticular like counts come straight back up, even though it's a blood loss. So, I just shove that in there, just to remind you that you've got to think about when did the incident happen and how does that relate. We've then got the acute leads us very nicely onto the acute haemorrhage, where we're going to see very few reticular sites because of that, this graph.
OK? We've got a brief time delay. But we might expect to see some low protein, not in every case, but we might expect to see that the proteins haven't bounced back up in the same way.
It is worth mentioning here that if you're doing surgery and you've got a bleed at the time and someone takes a blood sample from your dog or cat that's bleeding, everything will be normal. Unless you're really pumping in the fluids. OK?
So you, because you're taking blood and the blood is being lost at this rate, and you're taking a sample, it's going to look like normal blood. So it's not until everything's kind of retabilized that you can really get a clear idea of, of the severity of the anaemia and the severity of the problem that's, that's coming that way. So, moving on to the more chronic haemorrhage, and this is the ones that, that more commonly present with a severe anaemia.
Acute haemorrhage, if you've lost more than 20% of your blood volume, you're dead. So, tends not to be a really bad anaemia. Whereas in chronic haemorrhage, because the blood loss is ongoing and insidious, it can take quite a while, you know, for you to kind of lose enough blood to become severely anaemic.
You're losing a little bit each time. In theory, we should have a really strong reticular site response, because we're over here somewhere in this curve or even, you know, right over on the right hand side. But if you lose enough iron, so if you're losing that blood outside your body, and this would typically be gastrointestinal haemorrhage, would be the most common reason.
And I think probably the, the main reason I've seen this has been gastrointestinal bleeding, with severe IBDs, gastrointestinal ulceration, and so forth. If you've lost enough iron, then you can't regenerate. And in that situation, you are also losing protein.
So you might see a low protein as well. OK? And that will really just depend on how long it's been going on for.
And this picture under here just shows you a really beautiful slide, and we'll, we'll probably see this again in a minute when I'm talking about iron deficiency anaemia, but it shows you that, that really striking appearance that you get on a blood smear. And then over on the far right here, talking about a hemolytic process. In the hemolytic process, we expect to see a really strong regenerative response.
These red cells are being broken down and recycled by the body. The bone marrow's working overtime to try and pump more out. OK, so generally with hemolytics, we're gonna see a strong reticular cy response, and we will see a normal protein, because the proteins shouldn't be affected in any way by this process.
And you can see on this picture here, this is a a dog that actually presented to me looking like this. I haven't adjusted it. I, I'm glad I've got the fingers in to prove that I haven't sort of turned this dog this horrific colour.
Because this was a severe jaundice. But as I was saying earlier in the talk, you can see, I think straight away, that there is no pink under that sort of yellowy green revolting colour that this poor dog has. There's not pink underneath there.
So this looks like an anaemia plus a jaundice, as opposed to a normal PCV plus a jaundice, where there's that pinky tinge underneath. So I just want to quickly touch on emergency management, because at this point in time, this is where I'm gonna jump in with my emergency management, OK? I've still got investigations I want to do, but I'm going to really start thinking about whether I need to jump in at this point.
And that is part of the. Approach to anaemia, not letting the patient die before you've done your investigations. So number one, minimise stress.
Don't stress it out taking a blood sample and make it walk all the way down the long corridor to get to the place where the blood sample is. Lesson learned by me. You can oxygenate them.
Remember that they can't carry as much oxygen because of the lack of red cells, but you can increase the dissolved oxygen, just a little fraction, and it might help them a wee bit. OK? So it's not gonna fix the problem, but it might help them a little bit.
It's probably not gonna help them enough if they're really stressed out for you to then do procedures. And in that situation, you need to consider whether a blood transfusion's needed. And my criteria for blood transfusion is clinical compromise.
OK, so in the patient that can walk up the stairs and has a very low PCB, that's not clinically compromised at the present moment, OK? It might become clinically compromised, so I might need to think about doing it, but it's not an emergency situation. Whereas this patient here, this, old English sheepdog presented collapsed, it's PCV wasn't as horrific as you might have expected, considering its condition, but it's clinically compromised.
Wherever the PCV has gone below 10%, the chances are, even if this is chronic, they're going to become clinically compromised very quickly. So it's probably worth transfusing them. And particularly in patients where the PCV has fallen rapidly down below 15%.
OK? And that is, as we talked about before, this fact that the body just hasn't had time to adjust to the fall in oxygenation. So we need to get it back up pretty quickly, pretty smartish.
We can also consider IV fluids, and this is really important in hemolytics, because there is some evidence in humans that you can get damage to organs by kind of high levels of the, the product, the byproducts of hemolysis, the bilirubin and so forth circulating around the body. Now, I hear people go, oh, I don't want to do that because it's gonna dilute the blood. It's not gonna dilute the blood.
If you can genuinely dilute the blood with fluids, then the dog was probably dehydrated, OK? And what you're doing is restoring its circulation, and the, the anemia's worse than you thought. OK?
But you're not going to make the anaemia worse by giving it fluids. OK? Then it's not going to make the red cells disappear, unless you're giving some very, very strange fluids.
OK? So, really, no need to panic on that front. So once we've stabilised a patient, we're all happy that it's stabilised, we can start to think about how we investigate each of these different groups.
So first up, we're gonna think about investigating a non-regenerative anaemia. And as I said at the start, big number one, is it anaemia of chronic or inflammatory disease? This will tend to be a fairly mild anaemia.
OK? So we're talking about 30%, that sort of level in a dog, maybe more like 25 to 28 in a cat, something like that. Have a look for systemic causes.
Chronic renal failure is a really, really common one. Liver disease, endocrine disease such as Addison's and hyperthyroidism, iron deficiency, that should have regenerated. So it's a blood loss one.
So you need to kind of ping this one into when we talk about blood loss as well. And also thinking about the infectious causes such as FELV and Elichia. Has there been any history of drugs?
OK. And in my day, we were still using injectable chlorophenol, which can do strange things to your bone marrow. OK.
So it shows how old I am, makes me feel very ancient, saying, But that's life. I have seen that used in clinical practise. Fortunately, not recently.
And eye drops are fine, OK? Just if you're using chlorophenical eye drops, all good. Just don't use the injectable versions because they're not available anymore.
And if you've still got them on your shelves, that's a big worry. You can also see it with lead poisoning, and you may think lead poisoning. OK, but I, I, I'm even old enough to have seen lead poisoning, particularly during the time when everyone was redecorating old properties.
So as the property boom took place, lots of people were Taking down lead paint off the walls, and I saw a beagle that had gone round and was licking all the little flakes of paint that these people were taking off their their window sills and their window frames. And it was very old paint and it had a lot of lead in it. So that is a possibility.
And then, once we've ruled out all of that, we're really going to bone marrow disorders. OK? And this little picture, this little graphic here is, is to show you how anaemia of chronic disease works, but it also explains some of the other mechanisms, if you like, for non-genive anaemia.
OK? So, in this image, we've got a little kidney here that would normally be producing erythropoietin. So, in chronic renal failure, that's going to fall away and, and be a problem.
OK? And in anaemia of chronic disease, oh, sorry, I'll just go back a slide there. Da da da da da.
Where are we? Previous? There we go.
In anaemia of chronic disease, basically, what's happening is the body is switching off supplies of iron to A virus or a bacteria. That's why it does it. OK?
So it's take coronavirus, for example, exactly the same mechanism would be happening in our bodies if we had that. Our bodies are trying to shut down the capacity for that virus to replicate, and viruses and bacteria kind of need access to the iron. So I kind of see it as a locking down of my iron stores to prevent these things from Getting access and therefore multiplying.
The problem is the body's not very good at differentiating between, say, a bacteria and a virus versus another inflammatory issue, so it shuts it down, so it pretty much shuts it down in any form of inflammatory disease. OK, so. It's important to remember that because that process is going to happen very, very commonly.
In all of these diseases. I mean, we, we talk about all these diseases, they've all got a component of anaemia of chronic or inflammatory disease within them, and then they may have additional things on top of that. So here, I said I would talk a little bit more about, iron deficiency.
And as I say, I love this picture because, it shows these, empty red cells. These are little empty red cells, OK? Tonnes of them.
There's just a lot of central pallor, not a lot of colour in here, because there's just no haemoglobin, because there isn't enough iron to make the haemoglobin. And then on top of that, what you've got is amazing. Look at these platelets, ping, ping, ping, ping, ping, everywhere.
Tonnes of platelets. Tonnes of platelets. Why tonnes of platelets?
Because you need them to stop blood loss. So the body is reacting to blood loss. So this is a case, it's actually a, a dog that I saw that had a severe inflammatory bowel disease, and it was just losing tonnes of blood through its, its gastrointestinal tract.
And the body was. Trying to stop it by making more platelets, and the red cells were obviously failing because there just wasn't enough haemoglobin to fill the red cells. So they make little small red cells, and they don't have enough haemoglobin in.
So they are microcytic and hypochromic. You can confirm this particular condition by looking at low bone marrow iron stores. It's not a very easy thing to do in the cat, for a range of reasons.
But actually, if I see this, I probably don't need to really think about, other reasons for why. There's an anaemia, you know, a non-regenerative anaemia, this is why, OK, we've definitely got blood loss, because I can see that from the smear, and that's why I think smears are so important. But if we have ruled out all the kind of general reasons for nongennemia, we're going on to bone marrow sampling.
And there are different ways you can sample the bone marrow. I know that, that some practitioners are really nervous about doing bone marrow. OK?
This is the one time I do metal and bone. You guys do metal and bone all the time, OK? This freaks me out because it's metal and bone.
I didn't want to do it. I'm not a surgeon. You guys are surgeons, you're really used to this.
This is not a difficult procedure. And you can do different places. So I, I particularly like the wing of the ileum in dogs, and I like, my chocoteric fossa or my humerus in cats.
That's my particular preference. Those of you who are doing a lot of orthopaedic stuff, you'll probably have preferences that reflect your experience. Just to show you, in Europe, they often do these, you know, basically standing with local anaesthetic.
That, that kind of scares me because I, I just don't feel as, as comfortable with that. But that's because of the, increased frequency of things like Elia and so forth that they have to often test for. And I just did a bone marrow recently, at, at one of the practises I work at, and they had bought this gorgeous kit, OK?
And I was like, What are these bits for? OK. And if anyone's using this and you're going, What are these bits for?
This little video down the bottom, this link on the bottom of the slide here, it's got a great video, tells you what these bits are for. And I tell you what, lovely. So, when you're, when you stick your needle in, you then have to do this wiggling around thing that breaks it off.
Not anymore with one of these, OK? We've got one of these sets. No, we don't need to mess around.
We can stick this down. So now that I've learned what it's for, cause I, I opened it at the practise and I was like, what are these for? And they're like, We don't know.
They just came like that. So I just did my usual way. But I tell you what.
Next one, I'm using those bits cause it looks absolutely brilliant. And I can't wait to get trying on it. So if you want to see that video, it's a video about humans, but it's all kind of cartoony, so not too, not too yucky.
You can also take samples from the rib. I have to say, mixed responses for me. This is something that I've done when I'm staging, lymphoma patients rather than necessarily for an anaemia investigation, because you can't get a biopsy from here.
You can just get an aspirate. But you use a horse needle. That's what I call the, the pink ones.
OK? So the pink needles, you could, I think is 18 gauge. I'm old fashioned.
I like my colours. I like to say, Hey, pink needle, please, and not have to remember the numbers. But what's interesting is you can get aspirates just in a sedated dog, and you're just going into the costochondral junction up through the rib.
So into the rib, and a needle is absolutely fine. These pictures also show one of the ways you can actually use the sample once you've collected it. So if you just line your slides up, standing up, so there's a little slope, and then you allow the, the, the aspirate to just drop down, it tends to drop the bone spicules higher up the slide, and then the blood falls away.
And then you can make smears, just like you would if you were doing a fine needle aspirate. OK? This is not a Difficult technique.
So, it's, it's one of those ones where, you know, you prac practitioners out there go, Oh, I can't do a bone marrow. And I'm going, Oh my God, I can't do half of the things that you do. Or even 1/10 of the things that you do, and I can do a bone marrow.
So I think we need to encourage people to be a little bit more confident because it's not a difficult procedure. It's just knowing the process. Why do an aspirate?
Why do a biopsy? Personally, I like to do both, if I possibly can, because an aspirate is really quick. So an aspirate gives you a really quick result, but what it doesn't do is give you that structural appearance.
And when you've got a bit of an empty bone marrow, so in things like pure red cell opplasia, you'll get nothing. And you get really depressed when that happens. I still get depressed when that happens, cause I think, oh, I've done a rubbish job.
I didn't get a good enough sample. But sometimes you just don't get anything. It's called a dry tap, and you just, you know, you're sucking away with your syringe and it's like, Oh, there's nothing happening.
What is going on? And that may be the pathology. OK?
So don't beat yourself up if it's not going right. It might not be your technique. It might be the patient that you're working with.
The biopsy will give us much slower results, because it often has to be decalcified, but it will give us that architectural structure, and it would tell us what's going on. So what about going through other areas? So we've talked a little bit about non-regenitive, let's look at investigating haemorrhage, and I could, I, I have talks that talked literally for an entire hour just on investigating kind of blood loss.
So, you know, this is a, a very brief summary just to kind of give you a feel for what you need to do. Well, history and clinical examination are always gonna help you here. OK?
So, rule out, are there any external parasites, look for sites of bleeding. You could do a faecal occult blood test. I tend to use these as a rule out.
So there's a lot of chat about whether you should go on a vegetarian diet before you do it and how it all works. I tend to Say, if faecal occult blood is negative, then it's negative. OK?
And that doesn't have to have a vegetarian diet. If it's positive and you really want to know, is that genuine GI bleeding or as a result of stuff in the food, then, then you might need to think about vegetarian diets. So, personally, most of these patients present with a bit more dramatic Melina and things like that.
So they're pretty obvious. What about endoparasites? Look at your urine, take some radiographs, OK?
And then when you've looked at the specific sites, you can really focus down on more generalised bleeding problems. You know, is there a problem with the platelets? Is there a problem with coagulation?
And the symptoms are quite different between those two things. So we've got the symptoms associated with platelet abnormalities, which is going to be petiation, Melina, and there's some really nice pictures of that here. And just bear in mind that in some patients, and this seems to be a particular problem in spaniels, you just get gum bleeding, OK, as the only sign associated with the platelet abnormality and none of the other signs.
There's also, obviously, the, the wider coagulation thing, the, the secondary hemostatic disorders. And these tend to be big bleeds. OK, so big bruises, re-bleeding, where it won't stop bleeding.
You know, this is a dog that had a, a nasal, issue, and it just kept bleeding, bleeding, bleeding, bleeding. OK? This is a, a dog with haemophilia here, this German Shepherd, that's got a big bruise on its head, you know, following a surgical site, investigation.
We also need to assess clotting kind of capacity and the, the ability to form clots. So the way we're going to do that is to look initially at the platelet count, OK? And then, once we've said there's enough platelets, then we can move forward to things like the buckle s Where's my, my tongue gone today?
The buckle mucosal bleeding time. And then move on to things like the coagulation tests. And if you're very fancy in a very fancy referral hospital, you might also have thromboelastography.
With platelet counts, this is something you can do in-house, really, really easy. And there's lots of pictures here for you to look at. And, you know, it's probably worth coming back to this slide, even if you're listening to this live and just having a look at some of these images, because you can see really nice big clumping, which is a very common cause for having a low platelet count.
But if you are doing a platelet count, also just remember, if, you know, that On a machine, OK, this is the machine printout. You need to look and see what the overlap is here, because if you've got little platelets kind of here, they're overlapping into red cells. So it might be a size differential, and that is a big problem in cats.
So just bear in mind that your machine is not always the right thing. And spontaneous bleeding will happen when your platelet counts less than 30. So if you've got a platelet count of 125, that's not necessarily the primary reason why it's bleeding.
If you want to look at how the platelets are working, then really, the most useful thing you can do is a, a buckle mucosal bleeding time at that point. And that's why it's really important to know that your count's gonna be OK before you start, because if you do a BMBT without having checked the count, then it could be elongated because the count's low. There are other specialist tests, but they're not routinely available.
And, you know, so it's not something that I've even used very frequently. Moving on briefly to coagulation testing, you need to do the different tests. So we've got our APTT and our PT, and many people have these available to them in practise, but if not, you can send them away.
And they're testing different arms of the coagulation profile. And the theory with thromboelastography is it's testing all of this, and then it's also testing the ability to dissolve the clot as well. And the really key thing with coagulation testing for me is to remember the vitamin K related coagulation factors, OK?
Because, first of all, things like, coumarin toxicity or vitamin K antagonism, or vitamin K deficiency in cats with GI disease in particular, or liver disease, they are. Going to be the, probably the most common reasons for having a coagulation disorder. And because vitamin K affects these ones in, in red, so these are the, the ones that are vitamin K related, this one, vitamin number 7, factor 7, it actually has the shortest half-life of all of them.
OK. So that's why when you've got a vitamin K related problem, you tend to see the PT increase before the APTT. OK?
You might be seeing them at the point where they're exactly the same. They're both elevated. But you, if you see just the PT going up, then that tends to lend some more weight to it, potential vitamin K related issue.
I also touched on just the, the breakdown system, and obviously if we've got a lot of breakdown of blood clots that can also cause coagulation problems such as disseminated intravascular coagulation. So this is just a, a quick summary in explaining the different tests, which is fibridoggen. Your fibrin degradation products or FDPs, and then D dimer is just a little version of that.
OK. So basically, that bit is testing the breakdown ability of the clot and how much breakdown is taking place. So a lot of breakdown means a lot of coagulation factors have been utilised.
So what about investigating hemolysis? And I'm sorry, it is a bit of a whistle stop tour today, because there's just so much in anaemia. God, I can do a whole day on anaemia quite easily and still have lots to talk about.
So with hemolysis, it's really important that we look at any underlying reasons. Has there been any toxins, are there previous medications that have been given like antibiotics or anti-inflammatories that may be predisposing to an immune-mediated process? And look for any primary diseases because hemolysis can occur secondary to tumours or to other inflammatory diseases.
So we need to look for everything. We need to rule out infectious causes such as Babesiosis and so forth. Mycoplasma in the cat.
We want to look for Heinz bodies, and my good old friend, the schistocyte, OK? Because they can also be a sign of ongoing hemolysis. In cats, we want to test for FELV and FIV, and then we want to look for systemic diseases, do abdominal scans, chest radiographs, and possibly a Coombs test.
If we're making a diagnosis of an immune-mediated hemolytic anaemia, so we suspect it, we're going to see appropriate clinical signs, they may or may not be jaundiced, so don't assume because it's not jaundice, it can't be an immune-mediated process. There's going to be evidence of strong regeneration, which is what we said at the start. We will see spherocytes, which are these gorgeous little red rounds, round red cells.
They've lost their central pallor because a little bit has been munched out of them, by the hemolytic process. And we're going to have a positive slide agglutination test. If our slide glutination test is Positive, we don't need to do, another test.
We don't need to do Coombs unless we want to know the underlying cause. Is it, is it IGM? Is it IGG?
If it's negative, then we should probably still do a Coombs test to rule that out. And then we'll see other changes, leukocytosis, any sometimes ever. Of of disseminated intravascular coagulation.
But what this doesn't do is confirm whether the immuno process is primary or secondary. OK, the only way we can do that is to rule out the kind of secondary reasons. So things like mycoplasma in the cat, Babezia in the dog, cancer, and so forth.
Bear in mind that vaccination has been associated with an IMHA. So, generally they think about it being within the last 30 days, although I suspect it's probably gonna be more like 10 days being realistic about it. And if we haven't got any of those things, then it's probably an autoimmune condition, and it's a primary autoimmune problem, which is the most common one in dogs.
So we have to go through all this process, even though we know that the primary one is, is the most common. So I know that was a whistle stop tour, but I'm, I'm really happy to take any questions in the remaining time that I have, if anyone has anything they want to ask.