Good evening everybody and welcome to tonight's webinar. My name is Bruce Stevenson and I have the honour and pleasure of chairing tonight's webinar. I don't think that we have any new members in tonight, so no need for extensive housekeeping, as usual, questions into the Q&A box and we will deal with those at the end.

So tonight's speaker is no stranger for us here on the webinar vets, and we are very pleased to welcome back Doctor Binnou, who is a graduate of the National Veterinary School of Toulouse in France. After a one-year clinical pathology specialty internship in Toulouse, he moved to Canada. Initially, as a rotating intern at the Montreal University, then as a rotating intern at the Ontario Veterinary College.

He subsequently completed a small animal internal medicine residency and a PhD at the Ontario Veterinary College. Benomo is a diplomat of the American College of Veterinary Internal Medicine. And his area of interest includes haematology and immune-mediated disorders, bone marrow diseases, as well as urology and nephrology in companion animal medicine.

But now, welcome back to the webinar vet and it's over to you. Thank you very much, Bruce. Thank you for, for these, these kind words.

Full disclosure, I'm home, so my cats may jump on, on the desk at some point and make some noise, but I apologise in advance for that. Tonight we're going to discuss together transfusion medicine, and through this lecture, I hope we can, go over the pre-transfusion testing and why they are so important. Understand what triggers do we have to look for when we make the decision to give a transfusion because it's, it's, it's not 100% a benign decision that we make for our patient.

Important to know what type of products exist for transfusions and they are different indications, and I will, I will only focus on the, the most common products that you can obtain in general practise, and also how we administer these products to the patients. And finally, I will touch briefly on transfusion reactions, and look at individual patient risk factors. So the, the general definition of transfusion medicine is the intravenous infusion of a blood component, either whole blood or blood that has been separated into some subproduct, and this is obviously becoming more and more common in veterinary medicine.

It is available, quite broadly and it's actually something that is definitely feasible in general practise. Obviously big emergency centres, big referral centres will have a blood bank and probably have these products on hand, moreover, more or less at all times. And that will also vary from country to country depending on on regulation, obviously, but it's something that is more and more available even in primary care clinics.

So the products, where do you get the products? Some hospitals will have a blood bank, although in the UK the most common is to use the pet blood bank, which is a great resource and is available to any veterinarian and will ship blood to your practise within 24 or 48 hours. So again, I would encourage you to look into that if you have a practise where you have sometimes need for, for blood products.

And that is the, the most common in the UK. In Ireland, it's kind of opposite. There is no pet blood bank that would ship us, blood products, so we have a blood bank here at UCD, and a lot of practises around us have also these kind of volunteer programmes, and I'm sure some of you do have a blood donor that they know they can contact in case of an emergency.

Regardless of how you source your products, the characteristics of the blood donors are very similar. Obviously you want these animals to be healthy because you want them to be able to handle the blood donation, but you also want the product that you're going to obtain from them to be of good quality to give to your patients who are in need. So for dogs, we are looking at healthy dogs.

Usually we take dogs that are above 25 kg to make sure that we can safely take the amount of blood that we need. And for cats, we are looking at healthy cats that are above 5 kg. Depending where you live, infectious disease screening is recommended, and there are some very precise guidelines that have been published through the ACVIM for infectious disease screening.

I would say that in Ireland and in the UK, the infectious disease screening might be less intense than if you live in some areas with more endemic infectious diseases such as Southern Europe or if some of you are practising in North America as well. These animals should have an annual wellness screening again to make sure that both the donor is able to handle the donation, but also that the product that you're going to obtain are good for the recipient. Most dogs can have a blood collection without barely any sedation.

For cats, unfortunately, I mean, exceptionally it happens that you can take that much volume of a cat without sedation, but I would say that the vast majority of them are going to be sedated or heavily sedated for the blood the blood donation. So how do we collect the blood? Prior to any donation, you need to do a physical examination on the day to make sure that the donor is healthy and able to undergo the donation.

And you want to check at least the PCV and the total solid of the patient to make sure that he's not anaemic and there is no concern with that patient on the day of the donation. For dogs, the minimum donation is usually 250 mL, and that will correspond to the smallest bags that are available on the market. But most bags are from human medicine and we managed to collect up to 500 mLs from a dog.

So if you have a dog that is over 25 kg, you can easily collect 500 mL of blood in a collection bag. For cats, until now, we are using a direct, collection via a syringe with an extension and a three-way stopcock, . It's a bit more labour intense, I would say, and you need to make sure that your, your positioning is great.

In cats, we also usually replace the volume that we take by subcutaneous or intravenous fluids, depending if you have an IV access for the cat or not. This is a cat blood donation in the university I used to do. I did my residency at, we used to sedate the cat with ketamine and Valium, which we could argue is almost an anaesthesia, and we would provide them with flu by oxygen during the donation.

The area was clipped and surgically prepped, and then we would insert a 19 gauge butterfly needle with an extension and draw the blood through a 60 mile syringe. If you are afraid of coagulation and clots in your syringe, you could use smaller syringes and switch them. Which is great because you have a better control of the clotting in the syringe and you can keep the syringe agitated at all times, but there is a breach in the asepsy because you are replacing the syringe from the extension.

So no, no, no technique is really perfect. For for dogs, we use a syringe, sorry, we use a needle that is already mounted on a collection device and you can see on the right picture that you have several bags they are in . A depressurized unit to create an aspiration and promote the blood collection, or you can just use gravity, which is what we use here in UCD now.

The bags that you can see, the first bag is the bag with the anti coagulant, and then there are usually 2 to 3 bags that are attached to that first bag which will allow us to spin and separate the different products that we will prepare with one blood donation. So with one blood donation, what we try to do is to prepare different products because not all of the patients will need either the same volume or the same exact type of blood products and that is what we call component therapy. From 1 unit of whole blood you can prepare at least 3 different products and that allows you to maximise each blood transfusion.

Again, it allows us to treat any specific deficiencies with the right product and to work with volumes that are compatible with a safe infusion for our patients. The most common path for a blood donation is what you can see on the left of the screen with your whole blood that is spanned down into a packed red blood cells and fresh frozen plasma, and usually the packred blood cells are separated into half unit of packed red blood cells, which means that with one dog giving 500 mL of blood, we can obtain 3 products and potentially help 3 different patients. By using some different type of .

Centrifugation, we can separate the pack red blood cells from a platelet rich plasma and separate then a platelet concentrate from the fresh frozen plasma and obtain another type of product. However, you need a very specific spinner to do that. So, only very advanced, I would say blood banking units will prepare platelet concentrate.

And then that brings us to the different indications of this product. Why do we go through the hassle of separating them? Well, red blood cells, their usage is obvious.

It's for patients that are anaemic and are transfusion dependent because they need more oxygen carrying cells through those red blood cells. So patients with haemorrhage, hemolysis or decreased red blood cell production will be eligible for back red blood cell transfusions. The plasma is rich in coagulation factors and we will go through that a little bit later in the talk.

So obviously we will transfuse plasma to replace some of these coagulation factors. We could also consider to transfuse. Plasma to replace some proteins.

However, we know that the concentration of proteins that we have in the plasma would require litres and litres of it before we can significantly increase the level of proteins in the recipient blood. And finally, if you have access to platelet products, obviously patients with thrombocytopenia could benefit from platelet products. The platelet concentrate that I mentioned earlier is the most common one and it's probably the easiest one to prepare.

There are some commercially available . Platelets that are dehydrated and that are available through a human blood banking or veterinary blood banking units. Then we want to talk about the pre-transfusion testing.

So usually in the common imaginary of people, when you think of transfusion, you think of like a million tests before we start the transfusion, and it's not completely wrong. It's important to make sure that the product that you are going to administer to the patient is safe, and one of the safety that you process that you have to go through is the compatibility between the donor and the recipient. Just like in humans, dogs and cats have blood types, and so the first step of pre-transfusion testing is to blood type your patient.

It's important because it can prevent adverse reaction, adverse reaction being either detrimental directly to the patient, if it was a very acute, a very like severe reaction, but also detrimental to the patient in the sense that Maybe the reaction will be just a massive hemolysis of the blood products and overall, the patient will not suffer, but he will not benefit at all from the transfusion. So then that's money that has been wasted and time that has been wasted in treating your patient for his anaemia. In dogs, we test them for one blood group at the moment, which is the blood group DEA1 that has been recognised as the one leading to the most transfusion reactions.

Dogs can be DA1 positive or negative, and the distribution in the population is about 50/50 virtually. In cats, there is an AB system, a bit more similar to what we have in humans, with actually three blood groups A, B, and AB, AB being its own blood group with its own, . With its own genetic pathway and AB has been actually shown to be dominant over B.

So it's not cats that are heterozygous for A and B that are AB, it's really cats that carry an AB gene. There are point of care testing for blood transfusion blood typing, sorry, that are available to all practises. So I would encourage you to have maybe 1 or 2 on your shelves, because it always, always can be useful.

It's also very important to know the patient's transfusion history, because if your patient has already been transfused before, probably the blood typing is not going to be enough to prevent any sort of immunological reaction to foreign blood because as I mentioned, the blood type on It takes in account one form of epitope on top of the red blood cells, but there are other natural antigens that have been identified by the recipient on the foreign red blood cells, and the recipient probably has by then developed an immune response to these. Therefore, we perform what we call a crossmatch, which is a direct compatibility testing between a blood bag and the recipient. And if the blood bag is compatible, then it's safe to administer it to your patient.

It is important if you run a blood bank or if you obtain blood that you ensure that the blood type is written on each bag. The collection date, the expiration date should also be written on these bags and for traceability, the donor information should also be available on the bags. So if we go back to the blood groups, for dogs, as we said, the main blood groups are called dog erythrocyte antigen or DEA.

DEA1 is the most immunogenic, so it's the most important one and it is the one that we test for, but there are 8 different DEA groups that have been identified in dogs, but not all of them will lead to transfusion reaction. Dogs do not have naturally occurring alloe antibodies, which means that the DEA negative dog does not have antibodies against DEA plus, red blood cells, and vice versa. So.

In theory, in dogs, you could administer a first transfusion blindly without knowing the blood type. Taking the risk that if the recipient is negative and you are transfusing him DEA positive cells, he's going to immunise himself against the DEA positive antigen and will react to any subsequent transfusion with DA positive blood. So you will need to blood type that patient and cross match it for his transfusion #2 anyway.

Therefore, we would recommend that the blood type is performed before the first transfusion. In cats, we have that triple system with A, B, and AB. Cats have naturally occurring alloy antibodies.

Therefore, any mismatch transfusion, even the first one, can be lethal to the cat because the reaction can be very severe. The reaction between A and B are actually fairly strong, so it's, it's highly recommended to perform a blood type in cats before any transfusion. This is my favourite blood typing kit and I have no no disclosure to have for the company that makes them.

I just find them very practical, and very easy to use and, widely available. It's a chromatographic, method where you dilute the blood in the little cuule that you can see on, the right hand side here and then you just plunge this, strip here. And then once the solution has migrated all over, you clip it back into the little receptacle that you had at the beginning and you can read the control negative for DEA1, control and positive for DEA1, and that's a weak positive for DEA1.

There are other types of blood typing kits that are available, including these cards. I find the cards a bit more challenging to use but they are a little bit cheaper, so might be more available in some practises compared to others. There are more and more research that have been performed recently around blood typing, blood transfusion safety, and they have shown that there are obviously more antigens at the surface of the red blood cells than what we tend to believe a few years ago.

And if you think of humans, you have a blood type that is ABO. But you also have a recess which is positive or negative, and it's known that there are more antigen than that that may partake in transfusion reactions. So similarly in dog, they have identified another antigen that can be eventually responsible for transfusion reactions, and it was first found in a Dalmatian and was called then dull.

The dull antigen is naturally present in most dogs at the surf on the surface of their red blood cells, but sometimes it's absent. And in dogs that don't have that dull, who are dull negative, if you transfuse them with any dog who are most of them dull positive, they will sensitise themselves. Therefore, you will have a first transfusion that will be successful, but then you will cross match your patient and it will come back negative and compatible on the crossmatch, incompatible with all of the donors that you have.

Some breeds seem to have a higher prevalence for the dull antigen. As I said, it was first identified in the Dalmatian, but actually shih-tzu and Doberman probably a bigger carrier of that dull negative mutation. So in some blood banking programmes, they will try to identify some Dobermans and some shih-tzus, although shih-tus are not the best blood donors, but for small volume they can eventually help, but they will have they will have Dobermans for, blood banking purposes, but they will test for dull and identify some bags as dull negative bags.

Also, depending on the geographic area, the distribution in the blood groups can be different, so there is a blood group that has been called chi, that has been identified in Korea. Kai means dog in Korean, and that blood group seems to be quite prevalent, but that antigen seems to be quite prevalent in Korea and for example not really prevalent in the US. So the relevance of testing for it might vary from a country to another.

Similarly, in cats, they have identified also another antigen that can partake into immuno reaction to blood transfusion, and that is the M antigen, but in contrary to dogs, they have not identified breeds that would carry or not the positive or the negative MC antigen. So that leads us to the cross matching. As I said earlier, the cross matching is a direct testing between the recipient and the blood bag that you are intending to give that patient.

It's an immunological test for that compatibility, and it will look at any anticoagulant that is, any antibody, sorry, that is present into the recipient blood. That could attack and destroy the red blood cells that you're gonna give to that recipient. The most common one is the major cross match, and that is when you incubate the donors red blood cells, together with the recipient serum.

So that means that you are looking at antibodies present in the patient's serum that could destroy the transfusion bag that he's about to receive. The minor crossmatch is less common and it's something that is used a bit more in human medicine than in veterinary medicine. And it would be to perform the opposite and make sure that there is nothing in the patient in the donor's serum that could attack the patient red blood cells.

So, as I said, the cross matching is recommended if you don't know the transfusion history of your patient, or if you know that your patient has received at least one transfusion. The Time after the first transfusion during which you can safely retransfuse without doing crossmatch varies from authors to authors. In a healthy animal, I would probably say 3 to 5 days in our.

Diseased patient and most of them being on medication like immunosuppressant medication, probably 5 days is a safe enough cutoff to not cross match, but beyond 5 days, your patients should be crossmatched. In cats, it's been shown that it might decrease the rate of transfusion reaction. And so there are some evidence that we might need to crossma cats at all times, even for their first transfusion.

However, the time and the cost that it involves have not yet been shown to be worth the, the, the decrease in risk, but research have been showing that. Cats with cross matching might have less transfusion reactions, so there might be more papers coming out in the next few years. The interpretation is based on agglutination or hemolysis, so it's a very objective and direct visualisation of a destruction reaction when you incubate these red blood cells and the serum of the recipient.

In patients with severe autogenation, like patients with IMHA, the interpretation can be difficult. So I would recommend that you don't use like a bench up kit that you can buy for your practise, but maybe send the crossmatch out to a reference lab where they're going to be able to wash the red blood cells and probably have a technique that is a bit more advanced than the, the point of care tests that are available for cross matching. So now we have collected blood.

We have labelled it, we have stored it in a fridge. We can store blood for 28 days, up to 32 days if you have, a feeding solution for your red blood cells. So it depends a little bit in which condition, you've collected the blood and in which condition you are storing the blood.

But if you buy blood from the pedal bank, it will come with an expiratory date, and I would advise that you do not use it past that date because the risk for reaction and hemolysis of the blood are higher. The older the blood, the more likely your reaction may happen with your patient. So now we need to decide Is my patient actually gonna really benefit from transfusion?

What product should I give my patient? How much should I give my patient? When do I, do I say this anaemic animal needs to be transfused?

Yes or no? And that is what we call transfusion triggers, and they are mostly used for red blood cell transfusion, which is the most common transfusion that you will come across, in practise. The goal of red blood cell transfusion is to improve oxygen delivery to the tissue because you're going to increase the available haemoglobin to capture that oxygen from the lungs and driving, drive it around through systemic circulation to all of the organs.

But we know that transfusion can have adverse effect. We have talked about transfusion reaction. You can also overload your patient because if you think about it, blood is just a very natural colour it.

So we need to determine if the transfusion is needed and make sure that the benefits for the patient are more important than the potential harm that it can create. So it's important to know what are the criteria that you have to use to determine, do my patient need a transfusion? And for me, it's really based on clinical sciences.

And as you can see so far, we have not talked about, a precise number of hematocrit below which I would transfuse for sure because I think it's very important for me to consider how weak or collapsed is the patient. Is he dull, is he very lethargic? Is he very tachychotic?

Has the heart rates changed over the past few hours? Is he tachynck, does he have label breathing? And can I put all of these clinical signs together and say that they are just due to the anaemia?

Other indirect marker could be hypertension, if, if there is a, a shock or a loss of a volume that is very important in hemorrhagic patients, elevated lactate that could be a sign for poor perfusion of, the organs. And based on that assessment and based on the hematocrit, I will then make a decision for transfusion or not. If you were to transfuse plasma, then the triggers are more based on functional things and the most common plasma transfusion indication is coagulopathy and lack of transfusion factors.

So it's more, is my patient currently bleeding? Are my PT and PTT of the scale and do I hope to improve them with a plasma transfusion? Yes or no?

And does my patient need to go to surgery and I need to kind of increase the need for, coagulation factor. Let's say if my patient is haemophiliac or vulerbrand, obviously we want to maximise the chances that there will be no excessive bleeding during any sort of procedures. So now our products, we have a patient that has triggers for a transfusion, and he has triggers for a transfusion of packed red blood cells.

It's important to know that a packed red blood cell unit usually has a PCV of 60 to 80%. So you are giving them something that is really concentrated in red blood cells, which is amazing because it's really what they need. If you were to give them whole blood, you could use fresh whole blood or stored whole blood.

But the PCV is now down to the PCV of a normal dog, which is fluctuating between 40 and 50, 55% maybe, in, in like a greyhound or a bulldog. If you give them whole blood that is fresh and it has been collected within 8 hours and has never been refrigerated. You will also give them some platelets that are probably still active and you will also transfuse them some label coagulation factors that are usually lost after eight hours or after refrigeration.

If you store the whole blood, then you kind of lose this advantage of the platelets and the labi coagulation factors. But you still have a decent mix between packed red blood cells and, and serum. But you can imagine that in a patient that is normal volemic, he volemic, and has destroyed these red blood cells, you don't need to replace any volume.

You really need to replace just these red blood cells that are missing. So if you give whole blood. To achieve the same replacement of red blood cells, you will have to give a much bigger volume than if you use back red blood cells, and that's really one of the advantage of the component therapy is that you are not overloading your patient to give them the same number, the same amount of back red blood cells.

As we said, the indication for pact blood cell transfusions are anaemia and often associated with with red blood cell losses, such as IMHA where you destroy your red blood cells or severe haemorrhage like a hit by a car, hemo abdomen, and, and things like that. And if you want to give plasma to your patient, let's say it's a, it's a hit by a car patient that has like severe coagulopathy is in DIC and you want to give him plasma for you know, the coagulation treatment aspect of it. You don't have to use the whole blood.

You can actually use a a bag of bacter blood cells and separate bag of plasma and have a better control of how much of each component you give and have a better control of how you treat your patient. So for me, the indication for whole blood transfusion are really like limited to emergency, let's let's say you don't have access to the pet block bank in a fast enough fashion. The patient is dying in front of you, like very anaemia due to like severe blood loss that needs to have an intervention like in the minute, that for me are really probably the only times that I would consider a whole blood transfusion.

Now if we think of our plasma product, we have different types of plasma product and they have each different indications. So fresh frozen plasma is a plasma that has been separated and frozen within 6 hours of the blood collection. And it can be frozen for up to a year and it will contain all of the coagulation factors.

It will contain albumin, it will contain natural antiprotease, which are natural anticoagulant, and it will also contain immunoglobulins. After a year of storage, it is called then frozen plasma, and we consider that the most labind coagulation factors, which are coagulation factor 5 and factor 8, have now disappeared from that bag and are no longer present. Therefore, if you think of a patient with haemophilia, for example, who will need factor 8, you can't give them frozen plasma because there is no factor 8 available in that bag.

So, depending on what your patient is suffering from, you can use fresh frozen plasma or frozen plasma as we said. Most commonly we use it for rodenticide toxicity, and both would be a very good indication, and both would be very useful, because we are looking at vitamin K dependent factors. Haemophilia B is also fine with both because factor 9 is not labile and will be present in both fresh frozen plasma or frozen plasma.

However, if you have a liver disease associated coagulopathy, haemophilia A, von Werbrand disease, or a very severe haemorrhage with disseminated intravascular coagulation, fresh frozen plasma is probably your favourite product because it will really contain all of, these coagulation factors that you need, but also all of the antiprotease as well that are still present. Finally, the other products that we have, I said briefly earlier, we can have platelet, containing product, so platelet rich plasma, or platelet concentrate and the goal here is really to stop the bleedings. You don't want to really increase your platelet count, you really want to palliate the bleeding occurring due to the lack of platelet more than anything.

It is recognised that the platelet activity of this product is very limited and they are probably used up right away at any breach or any sign of sites of of bleeding. It is important to know how to calculate the volume and there are different types of formulas, they are available in most books. There is one textbook of, of transfusion medicine, so if you're doing a lot of transfusion, that's a book that you might consider buying.

But they are available in, in ECC manuals and ECC textbook. This is the formula we had on the transfusion form, where I did my residency, to help us kind of estimate the volume that we were wanting to give based on the desired PCV, the recipient PCV at the time of the transfusion calculation divided by the unit of blood PCV. And that is then adjusted to the blood volume of the patient based on the body weight of that patient.

The desired PCV should not exceed 25% because you do not want to inhibit the bone marrow. And to stimulate hematopoiesis, 25% has been decided to be the threshold that we would not go above to maintain sufficient stimulation for the bone marrow to continue to produce new red blood cells on it on its own. And also for patients that are very anaemic, it is recommended to eventually aim only for like 18 or 20 for the first transfusion.

Once you've calculated your volume, you want to start the transfusion administration and you need to have a transfusion record and a sheet on which you're going to record at least the 1st 15 to 20 minutes of the transfusion, looking at clinical signs compatible with potential adverse reaction. It's important to have a trace of the transfusion products that you've used. So these are the forms that we used to use where I worked, and did my residency before.

We have very similar forms here in Dublin and I would say most practises with . Which are used to transfuse patients have these kind of forms just for traceability to know which pre-transfusion tests have been performed and you can see on the form, it's gonna say, have you typed your patient, Have you cross matched your patient? It's gonna ask you the volume that you want to infuse, and there is a trace of the patient and the donor.

So we can, if there is a reaction, trace, which unit, were, at fault. And then the table at the bottom is really like CPR stuff with the mentation of the patient, the temperature, the pulses, auscultation for heart rate, respirate, any. Acute adverse reaction clinical signs such as vomiting, herticaria and things like that, that we usually monitor for the 1st 15 minutes and then during the rest of transfusion, I would say probably hourly, just to keep a trace and making sure that everything is going all right.

Before you start, you obviously want to check that you have received all of your results from your pre-transfusion test, and I know I repeat myself a lot, but it's just because it's so important to ensure that you are safely proceeding with the transfusion. Once you start giving the transfusion, you want to plan to have a line in which there will be no medication, no glucose, no calcium containing fluid that will be run through the same IV. So depending on which medication your patient needs, you may need to place a second IV line to administer the transfusion.

Ideally, you would like to be, to use a big catheter to prevent hemolysis by just pushing the red blood cells through something that would be too narrow. The red blood cells can be kept in the fridge until the time of the transfusion, and then they are usually brought up into the room, and by the time you fill up your sheet and you set up the infusion pump and everything, the bag will be back at room temperature. The plasma is kept frozen and it will have to be thawed.

So that's a 20 minute time that you will have to take into account where the plasma is thawed into like a bath that is at usually body temperature, so around 37 degrees. We recommend that the products for transfusions are used over 4 hours. So if you need more than one bag, we would recommend that you don't take both bags out of the fridge, unless you're going to give them very, very quickly, just because of, bacterial contamination and bacterial proliferation, it's a standard of care that the transfusion product should not be hanged on the pole for more than 4 hours.

So if you have to give 2 bags, give the 1st 1/4 hours and the second bag over the next 4 hours. If your patient is very critical, you can give your bag much faster, and if you squeeze the bag in in 1 hour, you can use the second bag right away in another 1 hour, but each bag should not be hung for more than 4 hours. It is important to wear gloves whether you are handling the blood products.

It's important also to make sure that you have the right administration device, including philtres and pumps that are compatible with blood products. The philtre will prevent for clots that might have formed during the storage of the blood to be infused in the patient and to create damages. And the, the infusion pump needs to be compatible with blood products to make sure that their action is not gonna create hemolysis and therefore decrease the efficacy of the treatment that you are actually giving to your patient.

As I said, we calculate the volume and therefore the rate based on the PCV that we want to aim. In cats, we aim for 20 or 25 and we usually reach 15. In dogs, we are aiming for 25 and we are aiming really not to go above the 25.

I guess it will depend on the cases. Probably for me, if I am treating a dog that has very severe haemorrhage, very, very acute haemorrhage, for example, a dog with like thrombocytopenia, I might be happy to go up to 30 because I know that he's bleeding so much that it's just an extra safety for me to bring him, maybe a tiny bit higher because I'm afraid of what he's gonna lose very quickly. But if I'm treating something very chronic, I'm really don't want to go really, really high, for several reasons.

One is again the bone marrow stimulation, but also the fact that the viscosity of the blood has changed when they have been anaemic for a very long time. And so you don't want to super acutely change the viscosity of the blood, you want to do that gradually, so you don't want to change the overall quantity of red blood cells too much by giving a transfusion. If you have a very acute blood loss, as I said, if your patient is very unstable, obviously, you're going to do that 4 hour infusion, you're gonna give it over like 3 hour, 20 minutes.

Blood is a natural choid. So you could bolu it like you would bolu colloids in a hypotensive patient if you need to. The only thing is to test those.

I have 2 patients for which I didn't do a test dose because they were just dying in front of my eyes, so we just followed the blood in, but. Usually, even in an emergency situation, we would recommend to do a test dose for 1520 minutes with a very, very low rate and then you increase the rate to what you want it to be. If you have an anaphylactic reaction to a product, in this case blood, it is an immediate reaction.

So it really doesn't need to be more than this 1520 minutes for the test those, to rule out anaphylactic reaction. And then the rest, if it's another kind of reaction, we will discuss them in a few minutes. This is less of a problem and you can go full speed for your transfusion.

Obviously you want to be careful of volume overload. So again, if your patient is evolemic, you probably want to transfer them over 4 hours, so their body has time to adjust. .

And you can use the formula that I showed you a few slides before for the volume calculation, but you also want to look at the rate and make sure that you're not infusing more than 5 to 10 mL of blood per kg per hour, if you have a huge volemic or a normal volemic patient. If you're hypovolemic again, blood is a choloid, so you can use it as a bolus, you can use it faster, you can go higher in the rate, 20 mL per kg per hour is usually a nice colloid bolus and that's something that you can definitely do with blood or plasma as well. If you have patients with cardiac dysfunction, renal failure, where volume overload is going to be a massive, massive issue, you probably don't want to go above 2 mL per kg per hour.

And that's when as well it is important to calculate the volumes and the rates to see how much blood you take off of the fridge because maybe for the same volume that patients can take 6 or 8 hours and you want to be careful that you don't expose the product to too much risk in terms of bacterial contamination. Transfusion reactions are Rare. They are not uncommon.

You will see some, but. They are not That frequent and they are also Rarely life threatening. So as I said, an anaphylactic reaction like a, a lethal reaction to the blood transfusion are extremely rare and they should occur with like almost zero exposure.

Like, you know, people with severe peanut allergy can react to like just the the the the smell or just like a leak or something. It's the same with blood. The first few drops of blood.

Should create that anaphylactic reaction. I have never seen one personally, but it, it can exist. The other type of of reaction are just allergic reaction, type one hypersensitivity.

You can have hemolytic reaction that are acute or delayed, you can have some fever, you can have Some, some transfusion associated circulation overload, which is really like overloading your, your patient. You can have, lung injury associated with a transfusion which has been shown to be immune mediated. You can have also sepsis if the blood bag is contaminated.

And then you can have some changes in ammonia, phosphorus, and potassium. So for example, patients that are hypokalemic that that are going to receive a transfusion, I do not supplement them in potassium. I give the transfusion first and I reassess my potassium after.

And you could have infectious diseases. Transmission, however, if you have screened your donor, the blood that you're giving it should be sterile. So what are the signs of an acute transfusion reaction?

We said fever, tachycardia, vomiting. If it's a very severe acute reaction, you could have hives or swelling. You could have very severe hypertension in case of an anaphylactic shock, and you could have behavioural changes as well.

A bit more delayed, you could have hemoglobinemia and haemoglobin neuria due to the hemolysis of the product that you're giving. So these acute allergic reaction would be type one hypersensitivity. They are mediated by IgE.

You could have allergic, kind of non life threatening or anaphylactic, which is more life threatening, very, very acute reaction. The range of clinical signs depends on the severity, obviously, and what is recommended is to stop the transfusion, to check for hemolysis in the blood bag and in the patient, and monitor your signs of shock, put your patient on fluids, and we usually give them antihistamine and corticosteroids, and we monitor them, for a few hours with just that. If you have a proper anaphylactic reaction, you might need to go and administer ephedrine or adrenaline.

You need to administer probably H2 blockers on top of your antihistamine, and then you might need to help with the patient pressures either using choloids or eventually vasopressors. This is probably the most common one of the reaction that I've seen. It's the, it's a type 2 reaction.

So it's an IgG mediated reaction which takes a little bit of time to to set up and it's called acute febrile hemolytic reaction. It's what is observed if you transfuse the dog blindly and you happen to be negative and you gave him positive blood and then you gave him blood again, and it's positive blood again and he's gonna have antibodies against that second bag of blood. The severity is gonna be variable, but usually they have some fever, they are overall unwell, they are a bit tachycardic and mostly they have signs of hemolysis that develop within 2 hours, between 2 and 12 hours after the end of, the transfusion.

If the transfusion is not finished and you already see signs of hemolysis, tachycardia, or fever, you just want to stop the transfusion and fluid resuscitate them, but. If the transfusion is finished, you just want to make sure that you have them on fluid and you diaries them properly. If you identify this kind of reaction, you want to repeat the blood type or perform the blood type if you have not performed it before, and you want to record that this patient should really be crossmatched at all times for any further transfusion.

You want to also check the product that you are giving just to make sure that it's still on date. You want to maybe do a little hematocrit on the blood bank blood to make sure that it's not hemolyzed in the blood bag because It's, it would be difficult to see within the blood bag if it's hemolyzed or if it's just red because it's nice red blood cells floating there. And you probably want to culture that blood back to make sure that there is no contamination.

And there are some acute febride no hemolytic reaction where you are gonna have kind of like cytokine storm and massive white blood cell stimulation. But there would be no destruction of the blood product, which I guess is good because then the oxygen carrying cells are still present and help the patient. But this patient will become febrile during the transfusion, with an increasing temperature over one degree.

So they don't necessarily become. Hyperthermic, but the temperature will go from 37 to 38, and that is already abnormal. It can be an initial sign for something that's going to become more complicated afterwards.

It can be associated with infections as well. So the same type of precaution happened where you place your patient on fluid, you stop your transfusion, and then you do some testing on the bag as well to make sure that there is no contamination of the bag, that the patients were compatible, etc. Etc.

In fairness, if I have a patient that just has a mild elevation in temperature during the test dose or at some point during transfusion, I sometimes just reduce the rate by 50 to see if by stimulating less the immune system of the recipient, I have less of a response and things just go back to normal. But if they don't, after maybe 30 minutes or an hour, I will just stop the transfusion. You could have some like for vaccine, very acute reaction with facial edoema.

Again, not much you can do either you can stop the transfusion if it's finished. The dog had his face swollen like probably 2 hours after the transfusion was finished, and there is nothing really you can do about it except monitoring. There are some delayed hemolytic transfusion reactions which are kind of similar to what we've described, except that they happen within 24, 48 hours, up to 3 weeks after the transfusion.

They are often not associated with clinical signs and it's just dogs that have received transfusion and start to have like profoundly discoloured urine. And yes, they should eliminate the transfusion, but they should not eliminate it to the point that it's. Perceived by the owners at like like severe discoloured urine.

So probably then you want to check that they don't become anaemic again and that they don't need another transfusion, . There is no real intervention like there is no need to hospitalise this patient. It's just kind of monitoring their, their PCV and making sure that the a the anaemia does not recur.

So if you are administering a transfusion and you are suspecting or witnessing a reaction, you want to slow or stop the transfusion, and you want to make sure that you keep this patient on an IV support, just to. Continue to perfuse them properly. In humans, transfusion reactions are associated with AKI, but that has not been proven in in dogs that hyperbilirubinemia or free haemoglobin will create direct damages to the tubules, but I think it's a nice precaution to have these patients on fluids.

You want to monitor them for any complication involving their coagulation system, so DIC you want to enter their temperature, really go with your clinical presentation if there is a shock, you want to treat it, if they have respiratory distress, you want to give them oxygen, etc. And then you want to try to identify the underlying cause for that. So you want to check hemolysis in the blood bag, you want to look at the expiration date, you want to culture the blood back to make sure that there was no infection there, and again, go through your record of all of your pre-transfusion testing to confirm that initially this this donor and recipient were compatible.

Thank you very much for attending tonight. It might have been a bit theoretical, but I just wanted to make sure that we have time to go through everything, from pre-transfusion testing to blood collection to blood administration. And if you have any questions, I would be more than happy to answer.

Benoit, thank you very much for that. And I don't think there was any part of that that could have been left out because it's all so well intertwined and integrated, that it's, it's important to consider all these factors when you are considering a transfusion. I, I, I agree, yeah.

Yeah. We only got one question through. It was from Greg.

It came through quite early, so I think you have answered it. But, his question was, what percentage PCV would you decide a dog or a cat needs a blood transfusion? I will give two answers, or 2 cases probably, I had a boxer coming to see me once with a PCV of 10 or 12, I can't remember, and I never transfused that dog because he was.

Happy, bouncy, not tachycardic, not tacky nick. He was just pale, and yes, he was not able to go on his walk as he used to go before, but the anaemia was non-regenerative, very chronic. He had a bone marrow disease, so.

I, I did not decide to transfuse him because he was 10 or 12. I did decide not to transfuse him because he was so clinically well. We gave him a transfusion when we put him under anaesthesia to perform the bone marrow biopsy because obviously, being so depleted in oxygen carrying cells, he was at great risk for the anaesthesia.

But if I did not need to anaesthetize that dog for anything, I probably would have never transfused him and just treated him. On the other hand, I have seen dogs that have, gone from a normal PCV of 55% to 20% in 12 hours because they have immune-mediated thrombocytopenia and they are just losing blood everywhere you can imagine. And I have transfused dogs that were 20 to try to bring them up to 30.

So again, the PCV for me doesn't really make. A definitive cut off. Like I don't have a cutoff of a PCV to say yes or no, I will transfuse.

I really base it on my clinical exam, the need of the, the blood for the patient based on these triggers that we've described, earlier on. Yeah, and I think that's, that's a very true. I practised most of my early years in South Africa as a vet.

And, of course there we've got all your blood-borne diseases like your, Elis and your Bia and those things. And you get these dogs coming into the consult room and the owner says, well, he, he wouldn't chase the ball for more than 5 minutes and you check him out. His mucous membranes are either snow white or yellow, and you do a PCV on them and it's like 6.

And as you say, they walked into the clinic on their own, and the owner was complaining because they only chased the ball for 5 minutes and not half an hour as normal. And so they, they have a very, very strong adaptive ability. And it's, you've got to consider the whole patient, not just the numbers.

Yeah. Yeah. And if he's very chronic, if he's very slow of, Of, developing the anaemia, the body is gonna adjust to it up to a certain point that you can't anymore.

But if your patient is stable, I would not take the risk to transfuse him. If your patient is unstable, if your patient needs to go to anaesthesia, this becomes a much different discussion. And then for a dog with acute haemorrhage, where they lose either volume and they're hypovolemic, you need to replace that.

So you will as well transfuse them to replace the red blood cells. Or for patients with acute hemolysis, with IMHA, they become very dull, they become very, very, very weak. But I, I've also made patient worse because of their transfusion.

So, that's why I think the more you, you, you practise and the more you will do them, the more you will realise that. It's really fun and like I love to transfuse patients. I, I find transfusion medicine really exciting, but there are risks associated with it and it's important to not be focused just on the numbers.

Yeah, yeah. Greg has just popped another question in the, in the box they say, what about cats? Same for me, same, same discussion.

And cats are much more resilient to low PCV than dogs. So. Like students ask me numbers all the time, so I end up giving up and giving them numbers.

I say usually 15 for dogs and 12 for cats it's probably like. Most likely if I'm below these numbers, likely I will have to transfuse at some point, but it doesn't mean that I will jump on it. But the cats like cats are amazing and they, they come to the practise bouncy and happy and feisty and trying to kill you and their PCV is 1.

So. Again, I try not to use the numbers and, and go by what I need to do with them. If I need to do, being in a referral practise, I often have to do investigations and, and, and therefore I have to transfuse them.

But if you have a cat that's coming to your practise, you suspect mycoplasma or MHA the owners won't do much test. I, I would not put the money into the, into the transfusion. I would probably put the money in the treatment and eventually send the PCR for mycoplasma first.

Again, depends how clinical and how severely affected by the, by the anaemia they are. Yeah, yeah. Evaluate the whole patient, not just the numbers.

Well, Benno, I think you have more than shared your knowledge and educated us tonight. So thank you once again. And as always, it is a pleasure to have you on, the webinar vet.

And we really do look forward to seeing you, I think you've got another 1 or 2 during this year still. And we look forward to having you back. Thank you.

I will be back very soon. Have a good night. And to all of you that attended tonight, thank you very much to Dawn, my controller in the background, as always, for making things run smoothly.

Thank you very much and from myself, Bruce Stevenson, good night.