So good evening everybody, and thank you very much for joining us for tonight's webinar, which has been very, very kindly sponsored by the wonderful Pet Blood Bank. Tonight's talk is by Kate Murphy, and Kate has been working in referral internal medicine for over 20 years. Firstly, as a medicine resident, and later a senior clinical fellow in small animal emergency medicine and intensive care at the University of Bristol.

She's been working in, she has worked in 3 private referral practises with busy first opinion practises attached and was clinical director in one of these practises. Kate joined IDEX as an internal medicine consultant in 2017 and enjoyed sharing her experience and pragmatic approach to medical cases. She is a European and Royal College of Veterinary surgeons veterinary specialist.

And it's co-author of two textbooks of peer reviewed publications, continuing education articles and book chapters, and she has lectured widely on internal medicine. This evening, Kate is going to talk to us about canine blood transfusions. Why and when, what and how.

And if anyone has any questions, you can hit the the Q and A box right at the bottom of the screen, and you can type them in the type them in during the during the presentation, and we can put them to Kate at the end. So Kate, over to you. Thanks, Caroline.

And, I'd like to also thank the Pet Blood Bank for inviting me to, give this webinar tonight, and, my employer IDEX for supporting me, to prepare it and, and deliver it. So, we are going to focus on canine blood transfusions, tonight, and, the, the sort of plan for the lecture. Let's start by thinking about why would we consider giving a transfusion and, and when do we make that decision to, to actually give it.

We're going to look at how important it is to, blood type our dogs, and when we should consider cross matching in transfusion medicine. And then because with, the advent of the pet blood bank, it really has transformed transfusion therapy by giving us different products that we can use. I'm going to look at the different products that we have and the sort of choices as to when we use, different products and try to give you some guidance there.

We'll also touch very briefly on how we look after those products when they're within the practise. And then we're going to, focus more on how we safely give a blood transfusion, to dogs and, how we monitor and react if we do have a transfusion reaction. Very, very briefly touch on some alternatives, and if we've got time, I was just gonna use some cases at the end to, highlight some of that decision making.

So we're going to start by looking at why we would consider giving a transfusion. So there are many different reasons why people may think about giving a blood transfusion, and probably the two most important ones really that I would have on my list would be animals where we need to restore oxygen carrying capacity, and typically that's in our anaemic patients. And those with bleeding disorders.

So whether those are congenital or required coagulopathies, or secondary to problems with primary hemostasis, so problems with thrombocyte numbers, thrombocytopenia. Those really are the main considerations. Now, You can consider using blood and blood products to restore blood volume, but really, that's not a very efficient use.

You need a lot of blood to replace that volume and our crystalloid and or colloid fluids are a much more effective way of doing that. We'll also touch later on, on considerations that we can again use things like plasma, for managing patients with low oncotic pressure, but that would not be one of my, key recommendations, for using the product. So really we're looking at sort of patients with anaemia, and bleeding disorders are the main times that we'll be looking at using blood products.

So how do we decide when we actually need to give a transfusion? And this is, the million dollar question because it's not an easy question to answer, and does depend, to an extent on the individual patient, and also on, experience deciding when it is the right time to do it. So in the last slide on this slide, you've got two slightly pale animals and just being pale isn't sufficient reason to decide to give her a transfusion.

So we need to look at the signs that the patient's showing. And if actually they are pale and anaemic, but they are still well in themselves, so they Eating well, they're walking, they're not particularly tachycardic, and the anaemia is maybe not too severe, then I wouldn't be thinking about using blood products in these patients. But I'd have it in the back of my mind that it may be something I'll need to use if the clinical picture changes.

We often talk about what PCV should you transfuse at, and realistically, there is no specific PCV. Probably when you get down to about 10 to 12%, we're much more likely that we are going to consider a transfusion, even though if they are cardiovascular stable. But with some patients with severe non-regenerative anemias, they could be walking around very happily with PCVs of, of 10%.

They're not cardiovascular unstable with that, and therefore, it's not essential, unless, for example, we're planning to do a procedure under anaesthesia, where ideally we'd like to have the PCV around about 20% to make things sort of safe and more stable. So in those situations, we might consider transfusion. Even though the clinical picture is stable because we are going to anaesthetize the patient, but otherwise, it's very much looking at the bloods, but very much more importantly at the patient and what they're doing cardiovascular, whether they're having collapses and things like that.

When we look at, sort of particularly red cell products, the majority of red cell transfusions are given to patients with, blood loss, anemias and hemolytic anemias, and a, a lesser proportion to those with non-regenerative anemias. However, because we can have, some patients with non-regenerative immune mediated causes, those can be important ones where transfusions can buy time for drug therapy to work. So there are no clear cut things we need to look at the individual and how that individual is at the time, but there are some guidances as I've given you there to help decision making.

So when I first sort of started, and as Caroline said, I've been doing this for over 20 years now, we always used to say that it really wasn't that important to blood type dogs, before the first transfusion. It was essential to, type, cats, but that has, changed. So if we're looking for a donor, and obviously the pet blood bank does a lot of the work for us these days, but sometimes you will be, needing to look for a donor within your practise, or you'll be helping to select donors, from your client population to, assist with blood bank drives the pet blood bank.

We want dogs that are fit, healthy, free of disease, and fully vaccinated, so they need to not have any chronic illnesses. They need to not be on medication. Ideally between 1 and 8 years of age, and ideally more than 25 kilogrammes in weight, so that we're able to collect a unit of blood, which is usually around about 450 mLs from that dog.

We also ideally want ones with a PCV that's at least above 40%, both to impact on them and for collecting a unit with plenty of oxygen carrying capacity. Now, in sort of, the, the, the days gone by, we were less worried about infectious diseases in dogs that were acting as blood donors, but with the number of patients and pets travelling or being imported, we should be looking for donors that have never travelled abroad and have been born and bred in the UK so that we avoid some of the infections that can remain quite hidden. If, if you have got an unknown history, then we should be screening these animals for, infectious diseases.

Clearly, we don't want them on any medications and very importantly, we'd like them to have a good temperament so they don't mind donating. And they shouldn't have received a transfusion themselves because we may have some antibody generation if they have. So we have a number of criteria really that we need to use to select our best donors.

And then following on from that, we need to look at their blood typing as well. So we used to sort of use the term a universal donor, which referred to, dogs that were negative for, DEA for cy antigen 1. And, you know, when the blood bank started, that was the sort of blood that we were looking to have to transfuse into our patients.

But what's become evident over the time that the blood bank's been in operation, more blood typing has been done of the British dog population, is that actually the majority of As you can see from the slides, 70% of dogs are actually positive for DEA1, which means that when blood drives are done, positive units are being collected as well as negative. So to try and make the best use of the blood that is collected, it would be ideal that we blood type all dogs pre-transfusion. As that will allow us to choose a better type unit for the patient.

And also will avoid us, having the potential to be creating antibody, generation in some of these dogs. So there are certain breeds that have a higher prevalence of being DEA1 negative. So we have the sort of greyhounds and lurches, which are our reliable donors.

As you can see also German shepherds, pointers, Weimaraners. So a nice selection of, our larger breed dogs are there. But ultimately, with blood drives, when you're trying to find donors in the practise, you are reliant on who is available, and, and therefore, it becomes very important that we do do routine typing.

In terms of blood typing, therefore, I would now recommend that for all dog transfusions, this is considered. And, for the, the typing that we're doing routinely in practise, and through the blood bank, we're really at the moment only typing them for DEA one. But blood groups in dogs are a lot more complex than that.

So we have a whole range of DEA antigens, which they can be positive or negative for. And in recent years, there are other, antigens that have been found, related to different blood groups at the dowel. K1 and K2.

So over time, I'm sure blood typing will become more involved and complex in practise, but currently, we use what is easily available and what seems to be the most, clinically important type to look for. Dogs used to be typed as either DEA 1.1 or 1.2 positive and negative.

And, with the, blood typing cards that are used, from the company Alvidia, the quickest, and for a lot of research that they've done to back this up, we now know that, the DEA 1.2 was probably a variant of DEA 1 positivity. So with the, typing that we can do in practise, we now type to see whether they're DEA 1 negative, DEA 1 positive but weak, or DEA 1 positive strong.

And I'll come on to talking about the importance of that shortly. It's important to know that these tests that we use in practise to type dogs are reliable and give us the, the, the correct answer. So there has been work done correlating this to lab-based techniques with flow cytometry and immunochromatographic techniques.

And some of the important things to be aware of. Is that these have shown that the, little test strips are reliable, even if the patient is auto-agglutinating, and they're also reliable at low PCVs such as 5%, 10%. So, we can, trust the results that we're getting from the blood typing.

So it's a simple thing to have in your practise. You can have these kits. They come with lovely instructions that tell you how to use it and to use it properly because it's always important with patients side testing that we do follow the instructions correctly.

And essentially what happens is from putting the, the sample on the strip, we're looking for migration of the red blood cells across the membrane, which has monoclonal antibodies for the DEA1. And in terms of reading the results, it's very important, as with any test that you get a positive line in the control area to show that the test has worked. So you can see that in these 3 examples on the slide, we have a control that is positive in all three.

And if we look in the next column, which is the DEA 1, this is where we're going to find out our patient test result. So this first example here is a negative patient. There's no line in the DEA 1 column.

When we look at the one in the middle, you can see that we've got a weak line, particularly when we compare it to a strong positive. You can see here, this is a strong positive. We've got a nice strong red line in the DEA one column.

So this would be a strong positive. This one here is a negative. And the one in the middle is the one that we would count as a, a, a weak positive.

So this is how we can easily type our patients, and our donors in practise. And I would strongly encourage that this becomes a standard of care for canine blood transfusions. There are occasionally going to be problems with the test and so sometimes you may have problems with the red cells migrating across.

So for example, you don't get a red line in the control. We know that the test hasn't worked, and Alvidia has some very detailed instructions on how to manage this. So for example, sometimes in patients with severe icterus, which we might see with hemolytic anaemia or in those with a much less common condition of cold, gluten and disease, then the cells might not migrate.

The first thing that you could try doing with that sort of situation is incubating the blood and the buffer, for 15 minutes at 37 degrees, and rerun the test. If it still doesn't migrate, then, doing Washing of the red cells, and repeating the test, is what's recommended. And then there are further instructions on the, IV, site.

So it's a very useful, resource to, to look at and give you support when you're running these tests. So I guess the next question really is, well, having run the test, how do we use that information in our patients to influence what we're doing with transfusions? So, this is the sort of the, the current advice, and this advice may change in time as we get to know more.

But if we think about the patient that we've got in our practise that needs to receive a transfusion, If the patient we have is DEA1 negative on the blood typing, then we should transfuse that dog with DEA1 negative blood. OK? So that is absolutely clear cut.

The other one that's very clear cut is if we've got a dog that is a strong DEA1 positive, then we should transfuse that dog with DEA1 positive blood. The area which is maybe less clear at the moment is those cases that are weak positives on the DEA one plus. So we just get that sort of paler line in the, the column on the test.

We're not entirely sure, I think, yet, what the right thing to do, but the current advice is that we should transfuse those dogs with DEA 1 negative blood. The reason for that is if we were to transfuse them with DEA1 positive blood, we might not know whether that patient is weak or strong, or sorry, the donor is a weak or. And therefore, we might, we don't know, induce antibodies against the DA1 if we gave DA1 positive strong blood to a DEA1 positive weak blood recipient.

So for now, we use DEA1 negative blood for the 1 + weak dogs that need a transfusion. So that's where we're thinking about what the recipient wants. When we're thinking about a donor, if the animal comes up negative on the blood typing as a donor, they are a DEA1 negative donor.

That's clear. And if they come up positive, whether that's a weak positive or a strong positive, then they are considered a DEA1 positive donor. So overall, the main thing to remember from this is if it's negative, it gets negative.

If it's positive, Only if it's a weak positive is it, is it where you're not going to give the same type of blood that they've typed to. There, for the time being, you want to give them negative blood. So that's really the, the relevance at the moment for using blood typing in practise.

And the, the, the important thing really from using the blood that's collected. Is that given that we know that 70% of the dogs in the UK are DEA1 positive, what we want to do is try and use those units that are collected, where we can. So by typing the dog that's going to receive the transfusion, we can use DA1 plus blood more fruitfully because we'll know what our patient is.

Whereas, you know, if we go back 1015 years, we would have just said, we'll give them all negative blood. So this is a move on to try and make better use of the product. So what about cross-matching?

So I feel certainly with blood typing, things have changed. With crossmatching, we still have choices really at the moment. So with crossmatching, what we're doing is we're looking at a little bit more than just the DEA one status and whether they're compatible or not.

We're looking at maybe, incompatibilities with plasma proteins, with other cells, with the antigens, even on the red cells. So we're trying to look for our best matched transfusion. You can do this in your practise.

You can either use the test kits that I'll lead you again make or you can do this yourself in a fashion. And there are also more complicated ways of doing it in the laboratory. So essentially the, the, the main thing that we're concerned about when we're looking at cross matching is what we call the major and the minor crossmatch.

And with the major crossmatch, we're mixing donor red cells with the serum and plasma of the recipient and looking to see if we get a reaction. And that reaction is evident. By getting a glutinates or hemolysis in the sample.

So we're looking to see that reaction. If we see that, then that's not a suitable blood to use. And with the minor cross match, we're looking at using donor serum and plasma and looking for a reaction with the recipient red cells.

So if we had a patient and we cross match them against several units, and we have one that has a major crossmatch incompatibility and two that have minor crossmatch incompatibilities, we're going to prefer using the minor over one that has a major. Ideally what we want is to have all of those cross matches being negative, so we have compatible blood. Because we are trying to look for the best fit here, it's important to cross match against more than one donor.

And most of the cross matching, that gets done is, is done really these days through the, the pet blood bank and, and those samples are, are then, sampled at the IEX to look for these reactions, and a number of donors will be sent so that we can actually compare and look for the best match for the patient in the practise. If there's auto agglutination or hemolysis already within the sample, this makes it a much more challenging crossmatch, for the lab to do. So cross-matching, you know, can be done patient side, it can be done in the lab.

How do we use the information we get? Well, we use it obviously to choose the best unit to transfer you to that patient. And really, when should we be doing this?

Well, in the animal that's had a transfusion more than 4 days ago, they have the potential that they may have generated now an immunological response to the blood that they previously received. And so ideally in these patients, they should be receiving a blood type and a cross-matched transfusion to give the best chance of that blood that's going to be infused, surviving as long as we would like it to do. In patients that we don't know whether they've had a transfusion, it would be prudent to cross-match and try to reduce the chances of any, cross-match, incompatibilities.

And certainly in patients that have had a previous transfusion reaction, even if it was less than 4 days ago, then it would be sensible to crossmatch. It's been a suggestion that any, dogs that have had, a litter, should, be cross-matched in case there have been any. And other antibodies that have been generated.

The evidence for this is, however, a little, less strong. So you could crossmatch for any transfusion, but the main important ones are previous transfusion reactions and transfused more than 4 days ago. Those would be the major times that you should be recommending a crossmatch as a routine process.

So in terms of just trying to think about how we use this information in the practise, say we have a, a, a, a patient in the hospital and we feel that they need a blood transfusion. The question in our mind really should be, do they need it now? And if the answer is yes, then really we want to get blood typed, and if we've got in-house typing, that's straightforward and easy to, to do.

If in-house typing isn't available, I would recommend that you collect some blood into an EDTA tube so that you can get that tested outside of your practise if you haven't got the facilities in your practise at that time to do it. Because otherwise, if you do transfuse these patients, we could have a little bit of a, a confusing picture to try and type them afterwards, and it could be several months potentially before we can actually accurately do that. So I would strongly encourage anyone who's thinking about doing any transfusions in their practise to have blood typing cards available so that they can do this in practise.

And if not, just collect the blood so you can send it out and do it. And obviously, in addition, as we've, we've just talked about, if they've been, transfused, more than 4 days ago, you should also be cross-matching them in that situation. If a transfusion is more of an elective procedure, we're planning a surgery and so we have time to get the results, then certainly we want to make sure they're blood type.

And this would be another situation where it would be ideal to cross-match them so that we can give the best matched blood, that's possible. And certainly crossmatching when it's not in a, an emergency situation is a lot more easy to, facilitate. So we come on now to what products to use.

We thought already about why are we going to give a transfusion, why we should blood type and cross match and hopefully you'll now see the importance of blood typing, pre-transfusion for all dogs. Let's look at what products we have available. And this is again where the advent.

The pet blood bank really changed blood transfusion therapy for dogs in the UK because prior to that, we would collect a unit of blood from a donor in whichever practise we're working in. And normally we would just give that threshold blood immediately to the patient. In some, hospitals, they would have had better facilities for trying to separate, the plasma.

And I remember clearly, many, hours spent at Langford doing this when I worked at the university, and we had to go and use a centrifuge in, one of the, The buildings on site, but it really wasn't the most easy thing to do. We ended up with not very good separation of the plasma and the packed cells. So it's been fantastic since having the blood bank available that we now have a variety of different products that we can consider using.

So this is a chart from the Pet Blood Bank website, and you can look at this at your, your leisure, but just to sort of highlight the, the main benefits that this has had really for us, the blue stars show the preferred products and the rectangles show what we can use, if, if we don't have the preferred product available. So when we're thinking about patients with anaemia, historically, a patient with either a regenerative or non-regenerative anaemia, patients with coagulopathies, patients with poor blood volume would all have received threshold blood. Whereas now the preferred product for almost all of those really is packed red cells.

So by having the pet blood bank, that's allowed us to give the, the preferential product. And nowadays, if we have an animal that is bleeding due to maybe warfarin toxicity or one of the other rodenticides, and is also anaemic, then we would give that patient fresh frozen plasma and pact cell unit rather than giving them fresh whole blood. So it has changed the, the options out there for us.

I guess the only time really that I would, sort of be thinking about using freshhold blood is where I'm really wanting some platelets, because once you've stored blood, you don't really have any platelets that are particularly functional there once you get past, the, the initial period. The other things other than plasma, which I've talked about for sort of bleeding patients that has been useful with the blood banking is we also have products like cryoprecipitate, which we're going to come on to, and that sort of has concentrated levels of certain clotting factors, so it can be useful for our bomb Willebrand's disease, patients. When you look at the blood bank website, you'll find much more information on there.

And what we're gonna do now is just work through the individual products and their indications and some, some facts that I think are useful to remember about the different components. So whole blood, what we used to use and what you still can collect in your own practise, and you know, if you're collecting this for a patient. And actually you end up not having to use it.

You can store it as long as it's been collected aseptically and handled properly. You can store it in the fridge for up to 3 weeks at 4 degrees C. So it doesn't have to be wasted if you didn't end up needing it.

And this is, of course, how all of the blood starts off being collected and for the rest of the components, it's that they then get spun and separated into the component. Opponents In terms of practicalities when administering this, it's really essential when you're administering blood products that you don't, administer it through the same line as fluids such as Hartman's or ringers, because the calcium in these fluids can react with the citrate and initiate coagulation, which is the last thing we want to do with the blood product that we're infusing in. If we've collected fresh whole blood, as long as we use it within sort of 6 to 8 hours, then we have pretty much everything there, the, the platelets, the red cells, the, the factors.

Once we get past the sort of 6 to 8 hours, we start to lose viable platelets, and we start to get drops in clotting factors such as factor 5 and factor 8, and Bolibra's factor starts to drop. So, you know, this is a product that, we would use in the emergency situation if you don't have blood bank products available in your practise. The general rule of thumb is that if you infuse, 2 mL per kilo of whole blood to a recipient, then you'd expect the PCV to increase by approximately 1%.

So it can give you an idea of how much blood you might want to be giving. Say we want to achieve a sort of 10% rise, then we'll be looking at at least 20 mL per kilo to achieve that in the, the PCV. But now very much more what we're using in in practise is not whole blood, but it's packed red cells.

So this is where the blood bank has collected the blood and then separated it into the components of the packed cells and the plasma. And this naturally means that the concentration of the red cells is higher. So these products usually have a PCV in the range of 60 to 80%.

They have a longer shelf life as well. The, packed red cells are suspended in a small amount of plasma and also a nutrient solution, and they can survive, with proper storage for up to 42 days in the fridge. So, you know, you can have this, from the blood bank and store it until, until you need it.

Volume size of the unit is, is smaller, so it's, you know, a normal whole blood unit will be 450 mLs with a unit of pack cells we're looking at about 250 mLs in the bag. And in terms of raising the PCV, we're working on a general ratio that if you give 1 mL per kilo of fat cells, then the recipient PCV will increase by about 1%. So essentially half the volume of the whole blood will achieve the same response.

It makes sense. Again, we want to avoid fluids with Hartman's or ringers going into the same line. So if you've got a separate IV line, that's absolutely fine.

You can use these fluids, you just don't want it going through the, the same catheter, the same IV lines. There's no need, with the blood bank product to resuspend it in any saline or anything like that. The nutrient solution is adequate for that.

So really, when we're using packed cells, the, the typical patients that we're looking to use this in our patients with, immune-mediated hemolytic anemias or other forms of norvolemic anaemia. If you were to give these patients whole blood, you risk making them hypervolemic. And we can also use this in patients with blood loss, or hypovolemic anaemia, in combination with fluid therapy to expand their intravascular volume.

So basically, pack red cells are for our anaemic patients. It makes sense. Now we're gonna move on to sort of our plasma, type products.

So, I've sort of done this sort of visual thing to try and help us decide what sort of products we might want to use, and, and whether we need to use plasma type products. So the first question really is, does this patient, that I'm dealing with have a coagulopathy? If the answer is yes, then immediately plasma type products become much more sensible to use.

So for example, if we have a patient with a vitamin K dependent, coagulopathy, that could be through redenticide toxicity or from liver disease, then fresh frozen plasma, frozen plasma, or cryosupernatant, which is the, what's left when you make cryoprecipitate, can be a useful product, for these. If we have patients with von Willebrand's factor deficiency or factor 8 deficiency or fibrinogen deficiency, then cryoprecipitates is probably a preferable product because it's more concentrated, so we needing to use a smaller volume to get the benefit compared to, for example, plasma. Patients with DIC disseminated into vascular coagulation, if they're in a bleeding phase, will potentially benefit from fresh frozen plasma.

But in those sort of patients, it's really important that we find the underlying cause and manage that. Otherwise, the DIC is, is not going to go away unless we treat the underlying issues. If the patient doesn't have coagulopathy, we probably most of the time don't want to be thinking about using plasma products.

So there are sort of times when people do think about it. So for example, if we've got a patient with hypoproteinemia, we do have oncotic support if we use plasma products, but we need to use quite a lot. So generally, I would think about using either crystalloids or colloids if needed, and you can also use things like human serum albumin.

So there are alternative options. It's pretty rare that plasma will be the right choice in these patients. There are some sort of cases where they've got low immunoglobulins where frozen plasma or cryosupernatant might be relevant, but I would say these patients are few and far between in general practise.

So let's not worry too much about those. It's more the patients with coagulopathy that we're going to be thinking about using our plasma products for. So in terms of our products, we've got plasma, which is the main one really that most people look to order from the blood bank.

So it's a species specific. We're, we're looking at using canine plasma, obviously, in our dogs. It is a natural colloid, it does have oncotic support, but you need an awful lot of it, to achieve the oncotic support that you might be looking for, which is usually sort of cost prohibitive, amongst other, other things.

In fresh frozen plasma, you will have all your coagulation factors present, and we really need to be separating the cells from the plasma within about 8 hours of collection to get the maximum levels of those clotting factors. Otherwise, we start to get, drop in the factors 589, and in von Willebrand's factor. There has been some evidence that shows it's probably acceptable up to about 24 hours of separation.

That's obviously important for, the blood bank where they are travelling around the country, but need to do their separation back at base. So it's good to know that actually things are reasonable for a little bit longer. With plasma, it's been separated, and we have the fresh frozen plasma that then gets stored in the, the freezer and can be stored for up to a year.

And so fresh frozen plasma has a shelf life of a year. After that point, it's still useful. It then gets gets labelled as frozen plasma because now some of the more labile clotting factors will have reduced over time.

But for patients with things like rodenticide toxicity, frozen plasma is really good. It's still got good, good levels of factors 279 and 10, which are the relevant ones in, rodenticide toxicity. And this has a shelf life of up to 4 years, further.

So that's, a useful thing that actually for the main reasons you might be wanting to transfuse with plasma in practise, which for me would be the rodenticy toxicities, then this product will, will have a long shelf life for you. With sort of the change from frozen fresh frozen plasma to frozen plasma, there is some role there as it can be, in, in higher numbers that we might possibly consider using it as a volume expander so that the product doesn't get wasted. One of the things to remember is that when you've got a frozen product, that plastic bag that it's within can become quite brittle.

So we need careful handling of this product, not to get any damage to the, the bag. So I mentioned that you can use plasma for oncotic support, when you've got hypoalbumic patients, but I usually say you need bucket loads of the stuff, and that's why we, we don't generally use it. But as I said, frozen plasma is there as a potential option from the blood bank to consider using for the oncotic support.

For me, a lot of the main reason, or main drive in these patients is finding out why they're hyper. Anaemic and addressing that. And unless they have severe clinical signs as a consequence of the hyperalpinemia, I focus more on the diagnostics and then management rather than on trying to treat the hyperalpinemia with oncotic support.

I, my experience over the years has been that it often makes little difference to the outcome, but finding the cause and treating that makes a huge difference. So I also mentioned obviously in the, the initial table, the cryoprecipitate and cryoprecipitate and cryosupernatant come from taking a unit of fresh frozen plasma and semi thawing it and separating it. And this gives us the the cryo P, which is sort of rich essentially in factors 8, fibrinogen and vondebrand's factor.

So it can be really useful for hemohiliacs, patients with. Efficiency and patients with von Willebrand's disease, and can be used to pre-surgery, for example, in some of those patients to, reduce the chances of bleeding. So that's a very sort of select group of patients that you probably don't see too often in your practises, but worth remembering that we do have specific options for these patients.

So that's sort of quick run through the different products we have. For me, the majority of use is going to be the packed red cells and the fresh frozen or frozen plasma for the coagulopathies with a smaller opportunity for using other, other products such as the cryope and the cryoS. At the moment, there's no platelet rich plasma, available, in the UK, and that's why I mentioned, that really, when you need, platelets, the only option really is freshhold blood.

I could give you another lecture on, on the limitations of that because the platelets don't really last very long. So if you've got a patient with immune mediated thrombocytopenia and you give them a, a transfusion, those platelets will also get destroyed. But if you've got one that's bleeding into the brain, it might be a life saving, procedure to do to buy a little bit of time for medicines to work as well.

So it's really important that if you are using blood bank products, that you look after those in the practise to make sure they are safe to use when we actually need to give them to our patients. So it's important that storage requirements are followed, that they're stored at the correct temperature. And you should be using temperature probes in the, the fridges and freezers to make sure they are being stored at the correct temperature, that we use aseptic handling, both during the collection of any, units and then when we transfuse them into patients that we minimise the chance of any bacterial contamination, which could be, really very critically important for these, these unwell patients.

I've mentioned already that with the frozen products, you need to take care because the bags are fragile, so we need to ensure we don't get damage and, and certainly keeping them in their sort of ziplock bags to protect them can be useful. We want to thaw plasma obviously before we give it to patients and we want to have blood ideally at room temperature, but it's vital we don't overheat them. So whilst there are some studies looking at using microwaves and things like that, I would encourage water baths rather than microwaving and temperature monitoring of the water bath.

You don't want that to be too hot because that can damage the, the product you're going to infuse and cause problems. It's really important as well that we record the batches. So what, what unit we're giving to the patient in both the patient and practise records that we have traceability should there be any issues, any reactions to the, the product.

So moving on to the, the bit that's, really clinically relevant, how do we safely give the transfusion to our patient in the, the practise? Well, I've already mentioned, we want to, ideally administer the, the blood product, at room temperature. You can give the blood cold, but there are some negatives to doing that.

And so, allowing it to warm to room temperature in a water bath in the Ziploc bag is what I tend to practise. I've also already mentioned the importance of asepsis in handling the blood, handling the catheter in the recipient. So there's lots of different places where we can, have a positive impact to reduce the risk for infection in these patients.

What's also very important with the blood products is we administer them via philtre so we can take out any little micro clots or aggregates that might have formed during transfusion and or during transfusion collection and during storage. So in our larger patients, we tend to use giving sets with inline philtres. Which have a poor size usually between about 170 and 200 microns.

In, really small patients, and particularly in our cat population, we would often be using these inline, small philtres, the humanate philtres, which have a much smaller pool size of 18, micrometres. And, and these usually get clogged after about 50 mLs. So if you're using a, infusing a larger volume through those, they should be replaced after every 50 mLs of, of blood that's infused.

But for the majority of canine transfusions, we are looking at using these, in giving set, philtres, for the transfusion. And you can get single and double pronged, giving sets depending on what you're wanting to use it for. I'm sure many of us have used infusion pumps to administer blood transfusions, and I would just suggest that you check with the manufacturer of the pumps that you have in your practise to see if they are suitable for use with blood transfusions, because some of them can potentially damage the cells.

And once that may not be Immediately apparent, it can lead to reduced survivability of the transfer your cells. So we're we're expecting that, you know, a blood unit should last an animal at least 3 to 4 weeks and, and we may see it lasting much less time if we don't give everything in the ideal fashion. So I've mentioned the sort of how much in terms of the packed red cells, if you remember that 2 mL per kilo of whole blood or 1 mL per kg of packed red cells will raise the recipient PCV by approximately 1%.

There are other more complicated calculations that you can use to try and work out the right amount, but I'm a simpleton, so I like to use simple numbers. If we're looking at plasma or I'll be that fresh frozen plasma or frozen plasma or cryo, supernatant, then we're looking at a unit being viewed as sort of 10 to 30 mL per kilo. And for cryoprecipitate for our von Willebrands or haemophiliacs, then we're looking at 1 unit per 10 kg and, and the blood bank will supply it to you in those, sort of, those units.

So that information is all available on the blood bank website, so it's not information you necessarily need to stick in your brain. The only one that really I keep is, is working out roughly how much blood I want to give to get the desired effect, and that is going to be dependent on where the patient's hematocrit is and what I'm trying to achieve in each case. So in terms of sort of safely administering the transfusion to the patient, obviously, as I've mentioned, we need the philtres, we need the product to be warmed, we need our asepsis.

We also need good baseline monitoring. So before we start that transfusion, we should have some baseline cardiovascular monitoring, temperature, pulse, respiration, blood pressure, mentation, and ideally a PCV and total solids, taken in the period just before transfusion is going to be given. So we know our baseline, we know where we're starting.

And then in terms of the actual administration, we're looking at giving this at a fairly slow rate to begin with, so sort of half a mil per kg per hour for the 1st 15 to 30 minutes. And then if things are going well, we can double the rate roughly every sort of 15 minutes, increasing it up as we go so that So we're, we're aiming to give the transfusion over about 4 hours, and we, kind of increase that rate up to around about normally 5 to 10 mL per kg per hour. Unless they've got cardiovascular disease, in which case we need to go much slower, maximum of 1 to 2 mL per kg per hour.

If they're losing the blood really rapidly, we can go faster than that, but usually I'd be going from the 0.5 mL per kg per hour up to the sort of 5 to 10. That's my, my general rule of rule of thumb.

No real evidence benefit for pre-medicating them with antihistamines or corticosteroids unless they have a history of prior reaction. And the reason we want to try and get this infusion transfusion in over about 4 hours is we don't want to have the potential of bacterial multiplication. You can give blood transfusions through the intravenous routes, peripheral veins, or central veins, and you can also give them through in osseous routes if you've got small patients or very collapsed patients that you can't get intravenous access.

I've said no mixing, that means don't give fluids like Hartman's and, and, and ringers through the same lines, and also don't give drugs through that same line if you can avoid it unless it is a central line with multiple ports so that the, the fluids will be mixing in different ways rather than straight into the same bit. In terms of monitoring the transfusion, exactly the same sort of parameters that we measured before we start the transfusion. So we should be keeping a close eye on, the cardiovascular temperature, pulse, respiration, respiratory rate and effort, mucous membranes, refill time, and we're monitoring really to see if we have signs of a transfusion reaction.

So those sort of signs might be the Or becoming very restless, maybe vocalising. We might develop a pyrexia, might see changes in respiration and heart rate, changes in blood pressure, and sometimes we'll see sort of signs of more anaphylacticy type reactions, so facial swellings and urticaria. So it's really important to have a good baseline and to monitor closely for these to develop.

And the, the sort of frequency of monitoring really should be, constant for at least the first sort of 15 to 30 minutes, and then ideally every 15 to 30 minutes through the rest of the transfusion, and continuing post-transfusion, ideally for about an hour. So we pick up on any problems early. Once we've completed the transfusion, then, in the sort of a few hours afterwards, I'd be collecting some bloods to recheck what the PCV and total solids are, having completed the transfusion, and then usually within about 24 hours and then following on, depending on the individual patient.

And obviously using transfusion records is vital, recording the unit that's being given, and the monitoring and the pet blood bank have some suitable records for you to use. What about transfusion reactions? Well, this is something that, that we obviously are using our monitoring to look for.

And in some papers, they've stated the incidence can be even up to about 28%, but mostly we're probably looking at 3 up to about 8% of transfusions having some form of reaction. And these reactions can be immediate, and they can be hemolytic, so destroying the red cells or non-hemolytic in nature, and they can be immunologically or non-immunologically based. And these are the ones that we worry about while we're monitoring that transfusion.

And the ones that maybe get missed a little bit are those delayed transfusion reactions that occur up to a few weeks later or within the first sort of, the week. And, and basically, that's why the transfusion just lasts much less time than we expected to do. So, the dog is, is anaemic again, much quicker than we were expecting.

And there are a variety of different reasons and it may well be the sort of blood incompatibility. So this is another reason why giving type transfusions, cross-matched transfusions becomes very important. There are lots of different types of non-immunological transfusion reactions that are, are described as well.

So we can have the sort of acute anaphylaxis, and these are the ones that if we see them developing facial swellings in the other areas, we need to back off and stop the transfusion, give them antihistamines, give them some Oxygen, give them some supportive therapy, and then we might be able to, to restart, later on. But there are also things like patients that will have circulatory overload associated with transfusion and certainly cardiac patients are most at risk of this, but we can also see it in patients that have a normal blood volume and no cardiac disease. So that gets the the great name of Taco.

If you give loads of transfusion products, there is a risk of, the patient developing citrate toxicity from the anticoagulant in the, the, the blood units and potentially hypercalcemia. For me, this is very much more of a theoretical risk than a real risk. I've never seen it happen.

If we have clots and microaggregates get through, we have the potential for coagulopathy and thrombotic issues, and we have the potential for transfusions to transmit infections. So this is why it's important that we avoid, animals with known travel history, so we avoid things like Babia, but also that we do aim to, sort of screen them for other infections. And then we have some other great acronyms.

So we have transfusion-related acute lung injury, and febrile non-hemolytic transfusion reactions. And there's been some suggestion that if, leukor reduction or white cell reduction philtres are used during collection, which isn't standard at the moment in the UK, that this might reduce the incidence of these. Problems with hyperaminemia is usually seen that as, as blood is stored, the ammonia levels can increase and if you have a patient that has maybe hepatic insufficiency, that might raise their risk for developing hyperalaminemia.

Again, for me, this is much more of an academic theoretical risk than, than a real clinical risk. If you get a patient that develops a transfusion reaction, the main thing to do is to stop the transfusion and review things. Check that the correct unit was put up for the patient, check the bag, check the lines, see if there's any hemolysis, see if there's any debris like clots that you can see in there.

Collect a sample of the, the blood unit, and look at it microscopically to see if we can see bacteria and submit that for culture and sensitivity. Administer some oxygen that's never going to do harm and give fluid support. And certainly if it looks like a sort of an acute hypersensitivity, antihistamines and possibly some corticosteroids may help.

If we have a patient with sepsis and obviously we're going to treat the sepsis, and if we have a patient with circulatory overload, we're going to manage that with things like diuretics. So it's important to just stop, revisit things, and then try again slowly if you can and see if the patient is able to tolerate a slower rate of infusion once things have settled down. What are the alternatives?

Well, with pet blood bank, I have to say I rarely consider alternatives. There are times when we might, collect blood from an animal before surgery, so we can give it to them if they become, in need during surgery, and we obviously sometimes will, use the, measures of collecting blood from a cavity and reinfusing it, although I have, some reservations depending on the underlying reason for, the, the cavity bleed. In cats, because it's really difficult to get blood and we're not talking about cats tonight, but sometimes people will give dog blood to cats, so that's Xeno transfusion.

And in the past, we used to use an oxygen carrying support solution, oxyglobin, but if that's not available, we're not going to talk about that tonight. So we've gone through really all the different reasons why we might use transfusions and we'll just finish maybe with one case just to highlight some thoughts to us, about this before I take a few questions. So when you, when you're looking at this case, really want you to just think about, well, you know, is there any problems with the red cells if the anaemia is present, is it a regenerative or non-regenerative anaemia?

Do we get any indication of why we might have this anaemia from the, the, the smear analysis? Is the white count normal? Is the platelet count normal?

What other things might we consider? And the other thing we're thinking about really because we're thinking about transfusion obviously in this lecture is, is, is the patient clinically affected by the changes? Does it have ongoing active bleeding?

Does it have, exercise intolerance or collapse? Is it tachycardic? Is supportive therapy on its own fluids and oxygen going to be enough, or do we need blood products?

So I thought I'd share one with you that I was talking to a vet about very recently. This is Toffee, as a 1 year old female entire golden retriever, and the history is over sort of 2 to 4 weeks really that this dog had been playing roughly with some litter mates and had developed a swollen hind limb and had a shifting lameness, presented to the practise a bit weak and pale, but actually bloods at that stage had a fairly normal hematocrit. And 42%.

And then during the next few weeks, the dog had a bit of a soft cough, which is very episodic, not particularly strong feature, and it had some bleeding from its mouth. The dog also then came into season and started passing very large pools of blood, much more than the owners were expecting. Now, relevant to the dog's history, it is a dog from a farm, from a rural environment.

So if we look at the haematology and answer the questions that I posed, have we gotten anaemia? Well, now we have the dog has developed a very mild anaemia based on the red cell indices and the reticular sites. This is currently a non-regenerative anaemia, but this could be one of these ones that's in the pre-regenerative stage.

It hasn't had time to respond yet. The white cell count is normal, and another important question, has it got adequate platelets? We're dealing with a patient that's got bleeding, we want to know whether there's enough platelets there, and there are.

So we don't have thrombocytopenia. We do have a mild anaemia. If we look at this hemostasis algorithm from the online Eli path, we're looking at the sort of queries.

Well, platelet count in this patient is normal. So the next thing really to think about doing in a patient like this would be looking at screening coagulation tests. So we're looking to see if we've got a systemic cause of bleeding or a local cause.

And depending on those results, whether those are normal or abnormal will take us down the different pathways. One thing that doesn't really appear on these sort of algorithms is angiostrongs, which is the sort of French heartworm, and we know it can cause bleeding disorders. So unexplained bleeding, always keep in the back of your mind angiostrolus as well and consider testing and making sure we have appropriate treatment for that.

So with toffee, having a normal platelet count, but excessive bleeding, they ran an angio detect test which was negative, and they also ran some clotting times looking at the prodrom and time and the activated partial thromboplastin time. And what you can see from these results is that those are both very significantly prolonged. So we have a problem affecting both intrinsic, extrinsic, and common pathway if we look at coagulation simplistically.

And if we go back to the algorithm, we can see we've run the screening coagulation tests, and they were abnormal with prolongation of both PT and APTT. And this suggests either multiple or common pathway issues and is really most common with say vitamin K deficiency, so denticy toxicity, with liver disease or with DIC. So in this patient, the assumption really was what this this probable to be a rodenticide intoxication.

Now there are other things that could have been done, a toxicity screen could have been done. It could have had some the dimers look for evidence of DIC. It could have had some imaging done.

In this particular situation, the, the vets had, decided to treat the possible rodenticide toxicity. They gave the dog vitamin K, and they also gave it some plasma because of the active bleeding at the time and it was becoming clinically quite affected, very reasonable, things to do. And the plan was to reassess PT and APTT on treatment to make sure that the diagnosis was right, because the, the sort of the history with this dog is maybe slightly unusual, you know, we've got clinical signs extending over a month and certainly from the, the history, I was wondering if this was going to be more of a congenital Coagulopathy, something like a von Willebrand's or something along those lines, but one would only expect the APTT to be prolonged in that situation.

So having both the PT and the APTT very prolonged and with the history of being a farm dog, and with the angio tech being negative redeny toxicity seems likely. And the follow up bloods 10 days into vitamin K and plasma treatment showed that the prothrombin time and the activated partial thromboplastin time are now completely normal. So, that is a, a, a good way really of confirming that what we're looking at is likely to be red.

Site toxicity. This is definitely a dog where I'd want to go back in due course and see whether those times remain normal. So I'm running rather late, so I'm not doing any more cases I'm going to skip to the end now and we'll have our questions, slides, so that if anyone has any questions, I can try and take those.

OK, thank you very, very much for that. That was, that was really, really interesting. I always love listening to, the blood transfusion talks.

I find them just so fascinating. So we do have a couple of questions that have come through already. So if anyone else does have any questions, if you just want to go to the question and answer box, that's at the bottom of the screen and you can just type your question in, and then we can we can work our way through these.

So the first question that we have is from Sarah, and it's the question is, is it still OK to give the first unit of blood to a recipient without having blood type them? Good question, Sarah. So yes, it is.

and it, it is if you're using, the donated blood that you're gonna give is, is negative, so that you're using what would not cause a problem for anyone. But because of the fact that we know that so many dogs are positive and a lot of the units that are collected are positive, it can actually be pretty hard, for blood banks to supply enough negative to, to meet everyone's demands. So really to try and make the best use of that product and avoid wastage, I would encourage people to type, but it's not essential.

So unlike the cat where it would be bad not to type, with the dog, it's not essential. It's just good practise if we can get into the hang of doing that. Absolutely.

So the second one is from Karen. She's saying in humans that are receiving multiple transfusions, if they're going through cancer treatments, they may cross match them, but, but then just give what they can and then load them up with antihistamines and anti, antihistamines and paracetamol, etc. Prior to transfusion.

Is this because that they can group humans better? Is it, if, if in an emergency situation, could they use this, could this technique be used in a patient that's already had multiple transfusions without the time to cross match? Yes, I guess so.

I think I always come to some ethical concerns at this point as to how much is it fair and appropriate to give product to an individual patient if we've got an untreatable disease. That's another, another talk in itself. But, I, I think with a patient.

Which is that if you're burning through the transfusions so quickly, I think one does need to step back and just question what we're doing in, in, in a dog. yes, one could do it, but there's limited evidence that in a, in a dog, at least, that that's going to, make a difference to how long the blood lasts in, in my knowledge anyway. OK.

And then we have one from Jonathan. So if the, if the standard canine red blood cell normally lasts 120 days, but a transfusion depending on condition is about 4 to 6 weeks, then does this indicate even with good cross matching and accelerated rate of breakdown? And is this the red blood cell membrane damage or just minor incompatibilities?

Excellent question. Not sure I can answer that completely accurately. So obviously, the, the cells have been collected.

How long they're going to last is, is going to depend a little bit, as to how long they've been stored for as well. So, the longer they're stored, the closer they are to the end of their shelf life, that you, you probably will have a, a, a reduction in the length of, of, survival. It also depends on whether we've, appropriately addressed the underlying disease, and, and so we don't see, you know, that when you take a bag of blood, not all of those cells have 120 days of life left in them, would be probably my easiest way of trying to explain that as well.

OK, thank you. So then we have another one which says when do we need to perform cross matching in blood type cats? So we're not talking about cats, particularly tonight, but really for cats, the blood typing is the absolute be all and end all.

And theoretically, the reasons would be exactly the same in the dog than it is in the cat. Obviously in the cat, transfusion medicine is so much more challenging, because trying to find a donor is often the big issue, not multiple donors that you can crossmatch and show your best. Absolutely.

And then one final question is from Sue and she say asking, should we be using Plavix when we're giving transfusions for IMHA. I think, the question is, should we be using Plavix in patients with IMHA rather than just with transfusions? And certainly patients with IMHA are at, risk of, thrombotic episodes.

And there's some good reviews. Coming out from groups about, the use of antithrombotic medications. So yes, I think it's, prudent, does it, it, it doesn't relate specifically to the transfusion, though it's more to the disease that's underlying it.

Thank you. OK, so that's all of the questions that we've had for this evening. We've got a couple of comments that saying thank you very much for the fantastic presentation.

And, and then outstanding presentation, thank you very much, and I will, I absolutely, I'll top that off with a 3rd and say, I really, really enjoyed that, thank you very much. So again, I would like to thank, the Pet Blood Bank, for sponsoring, this wonderful talk this evening. I would like to thank Phil from the webinar vet who's in the background doing all the technical stuff.

And again, I'd like to thank Kate for an absolutely wonderful talk this evening. So I just would just like to wish you all, a happy evening and good night. Thank you for attending.

Bye. Thanks very much, Caroline. Cheers.

Bye bye. Bye.