Hi, my name is Kat Baxter Smith, and I'm a veterinary adviser for MSD Animal Health. And today I'm going to speak about thoracic ultrasound in calves. This presentation is called BRD, which is bovine respiratory disease, and what you can't see.
So thoracic ultrasound allows us to see under the surface of the of the lungs and find out what's actually going on. So in the agenda today, first of all, we're gonna look a bit about how can thoracic ultrasound or to improve the detection of bovine respiratory disease? Then we're going to do quite a lot about how you actually perform thoracic ultrasound.
So how will we do it in practise. A bit about lesion interpretation. So we've got lots of pictures and videos to look at.
How do you measure and score lesions? So how do you know how severe they are? We have some practical use, case studies, and then how you use it on farm as a service for farmers and even make it chargeable.
And then a summary. So it should be about an hour. So first of all, let's just look at the sensitivity and specificity of various detection methods for bovine lung disease.
So we've got here in the chart a a list of the ones which are most commonly used. So, if you're the farmer, when you're looking at your calves and deciding whether they're sick or not, you're most likely to look at what we call DART, which is depression, appetite, respiration and temperature. So, this is, this is what farmers would normally measure when they're trying to decide if the calf needs treating.
And this has a sensitivity and specificity of picking up lung disease of of around 60%. So there will be a proportion of calves that are missed, and there will be also some calves which the farmer will treat, but don't need treating. And the gold standard is currently widely kind of recognised as the Wisconsin score chart, which was developed a few years ago.
This is slightly better specificity, so it will produce less false positives. However, the sensitivity is still around 62%. So, again, the farmers won't pick up or the vets won't pick up all the sick cars using this detection method.
Auscultation, so listening to the calf's lungs with your stethoscope, it's actually quite poor specificity. A lot of lung pathology will not be picked up using this method. The sensitivity is OK and, around 60%, and it gets better with the more experienced user.
So that's that have been using their stethoscope and listening to lungs for a long time tend to have better sensitivities. Then we look at thoracic ultrasound, and there, there probably are more recent studies now. I know there are more recent studies now looking at the sensitivity and specificity of this, compared to postmortem, and one of these was a analysis, and it's shown that the specificity is very high.
So in these two studies between 90 and 100%, so it does not really produce false positives. You know, if you see a lesion, it is a lesion. And the sensitivity is also very good, so between 80 and 90%.
And so you're unlikely to actually miss many lesions as well. So it's a very accurate way to determine lung disease and calves. This is a good study, I think, showing how even small amount of lung disease can cause quite significant effects in calves.
So this study was done by some Spanish colleagues in 2016, and they looked at 484 calves evaluated in that pre-weaning period, so February to May for the presence of BRD using thoracic ultrasound, and they counted positive as being a lesion was seen over 1 centimetre. So in the graph on the left, just get my laser up. We can see that if the animals had no respiratory disease, their growth rate was around 742 grammes per day.
However, even just a small 1 centimetre lesion decreased the growth rate by around 100 grammes per day to 649, and a 2 centimetre lesion decreased the growth rate. By another 50 grammes per day to 604. So that, yeah, if you're adding that up over time, that becomes a very significant decrease in growth rates.
And if we look at the graph on the right, that really does show this. So as the calves got older, going up to 163 days, we can see that. The ones with lesions were weighing significantly less, and they didn't catch up to the healthy calves.
So, even a small lesion in the pre, in the pre-weaning period has significant effects on these calves, as they go into adulthood. So now we'll look at how you actually undertake thoracic ultrasound. And the good news is it's very easy to do, can be done by, pretty much any vet, as long as you've got a scanner.
So it would be the same scanner that you use for reproductive ultrasound exams. So first of all, you want to get your patient. So you want a calf, which is over the age of around 4 to 6 weeks is ideal.
However, you can do them really anytime from 2 weeks, up to adulthood, but certainly that 4 to 6 to 12 weeks is, is, is the ideal time. Dairy calves are easier just because they're more used to being handled, and they have less muscle and less hairy coat, so they allow you to get a better image. And you don't need to clip the hair.
You can, use surgical spirit. Make sure that the animal is obviously relaxed and calm, and, you are restraining it, but in a, in a gentle way. You don't need to generally, restrain these animals overly.
It's a non-invasive technique. So, you know, you won't be causing them any discomfort. You need your ultrasound machine.
So, as I said, you can use your standard rectal ultrasound machine and probe. I like to use a linear probe with, and you can have it on ovary or foetal sexting status, 3.5 to 7.5 megahertz.
The, yeah, transrectal linear probes are easier to use than the curver linear probes. So I would generally recommend those. Now you don't need to clip the hair, as I said, you don't need, ultrasound gel, particularly.
The only thing you need is a conducting agent is, isopropy alcohol or surgical spirit. And, you use this I often put it in like a garden spray bottle and use it to spray the coat, and that gives you a really good image. The main thing to remember is that you just need to use quite a lot of it.
So, if you're not seeing a good image, you probably just need to, to add some more spray. You do want the, the coat to be wet. So, yeah, it's, it's, it's shown that you need pretty much 50 to 200 mLs per animal.
If you want to protect your probe, put it in the finger of a rectal glove, that does protect it. You do not want to use KY jelly or lube, particularly, as, as a conducting agent, because they've got air bubbles in it. So, now you're ready to scan, and it's important to know what you're looking at.
And I always think it's good to remember the anatomy of the bovine lung because it is quite unique and different to lungs of other species. So we've got this drawing on the right, and you can see, I always try and follow the same pattern when I'm scanning. So I always start on the right and I always start quarterly.
So first of all, we look at the caudal lobe, then we go to the middle lobe, which is just behind the heart, the caudal aspect of the cranial lobe, and the cranial aspect of the cranial lobe. And we can see all of these lobes when we scan on the right hand side. Then we can move to the left, and again, I start on the caudal lobe.
I look at the caudal aspect of the cranial lobe, which is just behind the heart. And then we don't really scan this cranial aspect. It's quite hard to view because it's, very cranial and up up behind the elbow.
And also it doesn't, we don't get a very good image, so it's quite difficult to interpret. So it's, it's actually been shown that you don't really need to scan this lobe. And then we have a postmortem picture here just so you can visualise how that looks in real life.
So on the calf itself, the lungs are surprisingly far forward. A lot of people, when they start scanning, are scanning the abdomen. So it's very easy to do.
And if you're just seeing a lotus of black, lobby type stuff, then you're probably in the abdomen, you're probably scanning rumen or intestines. So you need to move further forward. And even in this picture here, the lungs are probably actually kind of more further forward than this, this square shows.
So, I normally look at the, find the last rib and then move at least 4 or 5 ribs forward from that, put the probe on, see what I can see. Often you'll see liver if you're on the right or spleen if you're on the left, and then you can move forward from there and make sure you're on the lung. So this is a general area, but yeah, calf lungs are surprisingly small.
And here we have a nice picture of how it would look, you know, in the actual anatomy. So you've got your, your liver here. So you would, you would normally see that first of all, and then you'd move forward, see the caudal lobe, the lung, the middle lobe, and the cranial lobe, and you'll also see the heart on both sides.
When you're on the left, it's a very similar area. So again, find the last rib, move, you know, about 4 ribs ahead and put your probe on, see what you can see. Normally you'll see some spleen, and then you can move forward and look for the lung.
And I tend to say to people, if you draw a line between the bone here, the hip bone and the elbow, so you've got a straight line between there, you can put your probe somewhere in the middle and that will generally find you the right area of lung to look at. Again, we have a nice picture here, just to show you how that would look like on the anatomy. So we have our diaphragmatic lobe, cardiac lobe, the heart would be here, cranial lobe, and then the apical lobe, which we don't really scan.
We hold the probe, so it's, it's basically parallel within the rib space. So you, well, when you start scanning, you'll need to make sure this is a very common mistakes that you're parallel within those ribs, because otherwise you won't get a good image. So you may need to move the probe a bit just to get that correct picture.
Once you're in the rib space and you're seeing a nice picture of lung, you can move up and down within the rib space to have a look around. And then once you're happy, you can move forward another rib space and repeat the process. And if you do that starting quarterly and moving cranially on both sides.
There's a couple of studies here which show the frequency of where lesions are found. So in this study on the left and I find this in real life as well, that most of the lesions are on this right hand side and in these more cranial lobes, and this is quite obviously because they are the dependent lobes. So when the animal breaths, and the way the trachea and the bronchi are, are in the anatomy, you can see that the the air will and all the pathogens that come in with that air will will be deposited into those more cranial lung lobes.
And obviously that's why these lesions are then found there. So do have a really good look . Just behind the heart and in front of the heart on the right, and then on the left, just behind the heart again, it's a common place for them.
But, you know, obviously very important to check all the lung lobes. So, now you know what you're doing. We're going to move on to identification.
So here is just some examples of things you can see when you're scanning. And what I'll do is I'll first go through how we scan and how normal lung lobe looks, and then we'll go to look at some interesting lesions. So we have a few interesting things here.
We've got some plural thickening, a lesion, and some entire lung lobe consolidation. And hopefully by the end of this presentation, you'll be comfortable identifying these. Just some arrows to show you what I was talking about.
We will go back to these pictures and look at them in more detail. So this is the first thing, as I mentioned, one of the most common mistakes is people don't have their probe in the correct orientation. So this is the image you want to see on the left.
You want to see a nice straight image with no kind of shadowing or artefact in it. And so if I could just point out what we're looking at, the, this, at the doors, the sort of the top of the picture is the, the closest to the probe, so where the probe is on the skin. So, our main landmark for knowing that we're actually scanning lungs is this plural line or plural surface here, and this is always identified as a bright, very fine, well obvious white line.
So it's this bright white line that we see coming across the screen. If we see this, we know we're on lung, and we know we're in the right place. Everything above this line is basically just skin, subcutaneous fat, and we're not interested in that.
Everything below this line is long. In a normal animal, the lung is full of air, and we know that ultrasound is actually not penetrate air. So what we're seeing in this image on the left is actually what we call reverberation artefact.
So it's the plural line being reverberated over and over again because the ultrasound beam hits the plural line and reverberate. Back to the probe and the probe records that. So this is normal lung.
There's, it's full of air. We get this reverberation artefact, and we know where we're in the right place and we're seeing what we should see. These are also called A lines.
So these straight lines underneath the plural line are known as a lines. And so, yeah, like this says, superficial is here and the deep as you go further down, this is the deep. If you get an image like this one on the right, this is not so good orientation.
So these are ribs. So if you're seeing these black shadowy structures, and particularly if you're seeing that the plural line is not straight, then you need to reorientate your probe, so it's more parallel within that rib space. So we can, we can identify some lung here we can see we've got the bright white plural line, right like white plural line, and we've got these a lines, normal A lines below it.
But the ribs are really interfering with what we can see. It's not showing us a particularly good picture. So if we can orientate that probe better, we'll get a much better image that we can use for diagnostic purposes.
So now I'm going to go through as if we were scanning the animal, the process I would follow and what we expect to see. So, as I said, I always start on the right hand side, and I think it's important to follow a process every single time, because then you'll be expecting to see the same things. And, you know, if you're doing a rectal scan, you probably always scan the one ovary before you scan the other.
So this is a very similar thing. So first of all, if we were to start on the right hand side and quarterly, we, I like to make sure that I can see the most caudal aspect of that lobe. So if I can see an image where I've got liver on one side and lung on the other, I know that that is the most caudal aspect of the lung, and then it's obviously meeting the diaphragm.
And then we're going into the abdomen. So in this image on the far left, we've got our bright white plural line, so plural surface here. A lines underneath, normal.
Then this is the diaphragm coming across and now we're on this side of the screen, we're into the abdomen. You can tell it's the liver because it has this sort of homogeneous and grainy appearance, and it always does look the same and it's always in the same place. And as the animal breaths, what you'll see is it moving forward and backward as the lungs are expanding and contracting.
And that's a nice image to have. So you know you're in the right place and you know your, your anatomy and your landmarks are there, so then you can start to move more cranially. So that's the the image I always aim to get when I start scanning.
Then I will move my probe more cranially, so I'll start moving forward within the rib spaces. And so we're leaving the liver behind, so we can see, on this middle image where my probe is now is the diaphragm. And if this was a video, what you'd see is the diaphragm, again, moving forwards and backwards as the animal breaths.
And we call this the curtain sign because it does look like it's a curtain moving forwards and back. And then we've got the bright white plural line here showing normal lung surface, and we've got these a lines underneath these parallel lines, and that is all normal. So normal healthy lung here.
Then as we start to move further forward, so we're probably like in the 5th intercostal space now, that what we start to see is that the lungs sort of dips away under our probe. So first of all, what we want to do is identify the plural surface. So we look for that bright white plural line, we can see here.
And then we will start to see these costochondral junctions, and they look like dark or black circles, circle structures. And they are normal, but they're not in the long field. So if we're starting to see those, we know we're starting to get a little bit ventral.
We need to move, move the probe a bit more dorsally so we can see lung, and, and we don't worry about those, they're not a lesion. They're perfectly normal, but we just need to move the probe a bit more dorsally. We can see the normal lung underneath here.
So this is again, normal lung, and this is our sort of second landmark as it were. So we know we're in the right place because we're seeing these junctions, but, then we continue to move forward. So now we are looking about the 3rd or 4th intercostal space.
So we're moving towards the heart. And you can see here we've got the bright white line of the plural surface, always look for that first. And then we've got our normal A lines of reverberation artefact underneath.
And then we've got the heart here, and we know it's the heart, it's going to be obvious because it'll be beating, it's big, it's black, you know, it's quite obviously the heart. And this is an image I would really like to get because this lung. Lobe here is, is really the one that's most prone to having lesions in it or having consolidation.
So I really like to get this image where I can see the heart on one side and the lung on the other. And if I can look at that lung and see that it's normal, like in this picture, I'm happy and I know that there's nothing, there's no problems here. So this is a good landmark image to get.
Then what we need to do, and this is the most challenging part, the part that people do struggle with the most, is move in front of the heart. We want to keep the probe, quite parallel, but moving it forward. So the probe is in this sort of orientation.
We sort of tuck it in behind the calf's elbow. And it, the calves don't, aren't bothered about this as long as you're doing it in the correct way. So you should they should, you shouldn't be shoving it so far forward that they find it uncomfortable, but it's just underneath the elbow, and then you tuck the probe in and then you sort of find it forwards and back so you can see, the image underneath.
And this is, this is, this does become slightly harder to interpret. You will have to do this a few times to feel confident in what you're seeing, but the main landmarks that you're looking for, first of all, you've got your plural line here, the bright white line. You've got your, air lines underneath normal.
Then it steps down, so you've got plural step here. And this is where you're basically reaching the end of that lung lobe. So we cannot see any further forward than this.
There's no more lung. And then you've got these two very small vessels, which are the internal thoracic artery and vein, and these are our most cranial landmark. And it does sometimes take a bit of practise to be able to see these.
They are quite small. But once you see them, you know you're in the right place and you know you're as far cranial as you need to be. There's no point scanning any further forward.
All you'll see is confusing stuff, and not long. So just make sure you find these vessels, you get that image, and then you can be confident that you've scanned all the lung you need to scan on the right hand side. And that does come with practise.
So I'm going to show a video and the Operator is moving fast. So this, this lady is a very good scanner. I'll try and play it a couple of times.
So she's starting on the most caudal aspect. There's the heart, so she's moved, to just behind the heart there. And so she scanned behind it, and you can see normal lung on the left image.
Now she's in front of the heart. You've got the two vessels just there, sort of three squares down on the right. So we'll play it again.
So now she's called the lung lobes. She moves forward. She's just behind the heart, so this is normal lung and the heart on the right hand side.
And then she scans over the top of the heart. And she moves in front of it, and here we can see the two vessels, 3 squares down, normal lug on the left of the image. I'll just play it one more time.
Normal lung here, scanning forward. You've got the heart, normal lung behind it, going in front of the heart in a minute. The two vessels will see.
Two vessels here on the right of the image, normal lung on the left, and that's completely normal. And, you know, once you get good at this, you can easily scan a calf in under a minute. So it does allow you to do lots of animals in a short period of time.
So you've done the right hand side, brilliant. Time to do the left, and I would always do both sides because you could easily miss something if you don't. So, we start in the same place on the left hand side.
So we want to find the last rib, move about 4 rib spaces ahead of that, draw an imaginary line between the tubercoccy and the elbow, and, start in the middle of that. So we put our scanner on. What we'll hope to see is some plural surface, so some lung, and then, on the left hand side, we have the spleen and the spleen is, similar in structure to the liver but brighter, so more eogenic and, more the grains of it is sort of smaller, I suppose.
So, it's, it's, it's a sort of brighter, and more grainy sort of structure. And we can see our plural surface here, so bright white line of the plural, and then we've got a normal A lines underneath. And again, this is the image I always like to have when I first start scanning on the left, because I know I'm at the most cordial aspect of that lung lobe.
So I'm in the right place here. I know where I am, my landmarks are correct, and I can then start moving forward and scanning the rest of the lung. So make sure you always Do follow this process because it will make interpretation a lot easier when if you're starting to see weird and wonderful things, if you know you're always in the right place, you know you're, what you're looking at is, is actually pathology rather than, an artefact of some sort.
So then we move forward and getting to sort of 5th intercostal space, and again, we'll see these this bright white plural line here, and we can see it. Coming across the screen and then we've got a normal A lines underneath and then we have our costochondral junction here. So this is out with the lungs and it's a, it's not within the lung field and it's a sort of dark circle structure.
And it's normal to see this, but we just make sure we don't go any more ventral than we are. So we maybe move the probe a bit more dorsally and because we want to see lung rather than costtochondral junction. But it's a good landmark.
Then as we move forward, we want again to look behind the heart as we know this is where most lesions are often found. So we've got our plural surface here. And again, this is the image I really like to get where I can see half lung lobe, half heart, and I know that I'm looking at the right place, and, and my probe is correctly positioned.
So we've got the heart here, we'll see it big and black and beating. We've got plural surface and we've got normal A lines underneath it. So there's normal lung and heart.
Then if we were to scan in front of the heart on the left, which to be honest, I don't do normally, and I don't recommend doing, because it can start to get a bit confusing and also, you don't actually add really anything to the sensitivity and specificity of the scanning procedure. But some people do it for interest's sake. You can still see some lungs, so you do get some right lung lobe coming in.
You also see some left lung lobe, that that very cranial lung lobe there. And then you'll often see the thymus, and it's a sort of triangle structure. It's always in the same place, but it can be variable in size and it can confuse people because it does look quite like a lesion.
So again, this is another reason why we don't always want to scan in that cranial left, area, because if we're, overinterpreting things that actually aren't lesions, that isn't great. But yeah, that you will find the thymus there. So I have another video, and this is the same scanning lady and just scanning the same animal, but on the left.
So that is spleen on the right hand side of the image. There we have normal lung. There is something that we call a comet tail here when I'll talk more about those.
There's the heart, and she's just scanned behind it. I don't think she goes in front of the heart. No, she doesn't.
So, this lady Carolina taught me to scan and she scans in the same way I do. So here we have the spleen. We have the lung in the left hand side of the image.
We have, we're moving forward over the lung again, little comets tail there, which I'll tell you more about the heart. The lung is just behind the heart. And then she looks at that and then she stops.
Good. OK, we'll keep moving on. So now we're gonna talk about lesion interpretation.
So how do we know what we're seeing and how do we know what's normal or not normal? So we have looked a lot at normal lung, and I think it's very important to know what's normal before you can understand what's not normal. It does depend very much farm to farm.
You know, some farms, you'll scan all the calves and they look very healthy and that's great. Some farms, you'll see a lot of lesions, and it does depend on the sort of farm you're going to, you know, if you're going to a dairy farm with lots of well. Vaccinated, healthy heifer calves, which are kept in very good good, good environment, you much less like to see lesions.
If you're scanning, maybe some calf res where they've all come and mixed from different sources, you might be more likely to see interesting lesions there. So, like I said, with the normal lung, the first thing you always look for is that plural line. So bright white line there, and then underneath, we have our A lines, and these are normal.
So air in the lung, normal A lines underneath the plural line. Then this is the same video basically that I played before, but you can see the lung is very normal here. So plural line, a lines underneath, moving forward.
Gets the heart, normal lung here behind the heart. And then I think we move in front of the heart in this video. Oh no, we don't, that's fine.
So, that's basically normal. This is also normal, but, with, with something of interest. So we have to be careful not to overinterpret what we see and What we sometimes see these things called comet tails, and you can see that in the arrows pointing towards these comment tails.
So if we were to look at this image, first of all, as we always do, we don't get too excited about what we see because we want to identify our normal anatomy. So we can identify our plural line here, normal, you know, bright white line, we can see our air lines underneath. So normal lung for the, for the first part.
And then we see these comet tails, and they do look like sort of shards of light coming down. And basically what's happening here is there is some sort of irregularity in that plural surface, which could be like a micro lesion. It could be some thickening or scar tissue.
There's a slight slight irregularity there, and the ultrasound beam would normally hit the plural line and, and it's smooth surface and it would reverberate back and show you a smooth line. But because there's an irregularity. The ultrasound beam hits it and reverberates back at a different angle.
And so you'll get these comet tails. They are very common. You'll see them in pretty much every animal that you scan.
And so we don't want to overinterpret them and, imagine that there's a lesion there when there isn't. However, if we start to see lots of these in one image, we might start to think that something's going on. So on their own, they don't constitute as a, a lesion, but when there's lots of them, we start to wonder if something is happening.
And we'll sort of, we'll sort of go into that a bit more as I go on. Let's see about this video. So we can see the comet tails coming down here.
So there's quite a few in this image, but unless I actually see a lesion, I still would say, this animal does not constitute as having a lesion. That's normal on there. OK.
So now we're starting to get into sort of more severe type stuff. So first of all, as we always do, we want to look for our normal plural line, so bright white line here. That is OK to the most extent, but then what we are seeing is quite a lot of these comets, so comet tail here, come out here, and then here is is where basically several come tells come together and coalesced.
And so this is When we call them be lines. So when we see, so normally a comet tell is a sort of discrete, very sharp line, a bit like this one. When we see more broad structure and the coalescing of several comets, we call this a bee line.
And we also are seeing a bit of a disruption in the normal surface of the plural. So there's, you know, you can see our bright white plural line here, but here it stops, and this would suggest to me there's, there is probably a very small lesion here. So, Anything that's under 1 centimetre, we don't classify as a lesion as such.
But it, it's still going to be, you know, that there is a there is what we call a beeline. And we, we measure the lesions by looking at the grid squares. So, your ultrasound machine should have the option to overlay the image with the grid squares.
The grid squares are 1 centimetre or they can be set to be 1 centimetre, and we measure from the surface of the plural lines. So here, To, where we first see the shadowing effect. And because, because this is a beeline, it's not so obvious, but when we see actual lesions, I will show you and it looks more obvious there.
So still, still potentially, not, enough for the animal to be sort of clinically affected, but starting to become more interesting. So here we have a bit more plural irregularity and thickening. You can see this maybe in the early stages of pneumonia, or sometimes you can see it when the animals had pneumonia and it is recovering, but the, there is still this scar tissue.
So this is a very, this is basically the same image we had before. And you can see the bright white plural line here, but then we have these comet tails and where they become thicker bee lines coming down. And the plural, it doesn't look as nice as the plural we've been seeing and the the normal images.
It looks thickened and more here. So this is a bit more severe. The plural line is there, but we're not really seeing much in the way of normal A lines.
We're seeing the sort of waterfall effects, which is multiple coalescing comet tails, and so we will call them bee lines and then potentially some lesion here as well. So we're starting to get a bit more exciting now. So now we're looking at natural lesion.
So if we look at the image on the left, we've got our plural surface. We can see that because it's our bright white line. We have normal A lines underneath it, so normal lung there.
But here, we can see a very obvious sort of disruption in the plural line and a disruption in those normal A lines as well. So this is a lo or lobular or lesion. And which is also an area of consolidation of the lung.
So because it's the lung is consolidated, the ultrasound beam can now pass through it. It can pass through tissue but not air. So it then passes through the lesion, hits the far side of it, and then reverberates back.
So we get a nice image of this lesion and how we measure it, as I said, is we measure from the plural line or where the plural line would be to the start of the shadowing effects. The shadowing is, is, is the shadow of that lesion, basically, where the ultrasound beam is reverberated back. So if we're looking at the grid squares, we measure from the plural line here.
And so it's probably just over 1 centimetre this lesion would be. And so we definitely consider that to be significant. And then we have a video which I'm just gonna play.
So you can see quite a significant lesion here. There it is in the middle of the screen, and you can see normal lung on either side of it, that's the heart there. So there was normal lung on either side of it, but quite an obvious lesion.
I'll play the video again. I might even be able to pause it if I'm clever. So just play Pulse.
No, doesn't want to pause. That's fine. There we go.
So we can see we've got a plural line, which is just about one grid square down from the top, normal lung, on the right and left hand sides, and then a big lesion in the middle there. And if we were to measure this going from the grid squares, it looks to be about 1.5 centimetres.
Now you can see it. And then if you didn't, if you weren't sure, there's a nice green arrow which has just come into the lesion on the other side of the screen. So a lot of them do look like this, quite nice and obvious.
So now we'll get into more severe type consolidation, so larger consolidation. So if we look at this image on the left, we have our bright white plural line. We have our A lines underneath.
Then we have a very quite large area now of consolidation, and you can see it starts here with the plural line should be, but the plural line's been disrupted and it goes all the way down to probably about 2 grid squares below. So it's at least 2 centimetres. And so that is a significant area of consolidation.
Then again, in this picture on the right, we've got some plural line here and here, we know where the lung should be. So maybe some normal lung here, definite area of consolidation here. And you can see if we start to measure that from the grid square, it's probably about 1 centimeter.5 then a smaller area of consolidation here, which is probably just under 1 centimetre.
And then we'll get into the more severe stuff. So On this image on the left, this is actually a full lung lobe fitness consolidation. So, it can be when you first start to see this, it can feel a bit confusing because you're not used to looking at lung that looks like this.
So first, we have to make sure we orientate ourselves, make sure you know where you are in terms of the anatomy and your Landmarks, the plural line is here, but it's very thickened and inflamed. So where my laser is now, this is actually the plural surface, but it's really, as you can see, it's very thickened and it's not that nice bright, discreet white line we normally get. And then underneath it.
So this is a cranial lobe. You can see the whole lobe is actually consolidated. So this, this line here, which I've got the probe on now is the plural surface on the far and far side of that lobe, and then all this in between is all lung lobe.
And because we can see the structure of it, it is, we can, we know it's all consolidated and actually it doesn't like liver. And so sometimes it's described as hepatternization. So that is a full lung lobe thickness consolidation, so that's quite severe.
But surprising how often we do see this. And then this image on the right, slightly less nice, floral line would be here, fluoline again at the bottom of the lobe. This is the, the lobe that's consolidated.
This is, some heart vessels here on the, on the left. So again, fully consolidated lung lobe. And some arrows just to point that out.
So some videos, these videos were taken with a horse tendon scanner, which is why they can, they look a little bit different to what you might be used to when you use your rectal probe. This one on the left, we've got the bright white line here of the loa, and then we have normal lung and the hard left of the image, but then all of this is consolidated. This is the heart beating away in the bottom right corner.
This is a consolidated lung tip. You can see it does look quite a lot like liver, doesn't it? So, you make sure, you know, you know you're in the right place because you've got the heart there and you've got normal lung here.
So you know it is lung. But yeah, it's, it's quite interesting to see how different it can look when it's consolidated. And then on this image on the right, and this is a curvilinear probe, which is why it looks a bit odd, but you've got your normal plural line here, normal lung here underneath, heart beating in the far right corner, but then consolidation here, all of this area is consolidated.
And as I said, it is really common actually to see that the lung lobe just behind the heart is, is consolidated. That seems to be the place where it, it settles, as it were. So it's really important to check that area quite thoroughly.
And then getting into the more severe pleural effusion, so fluid, and you can also see it's probably fibrin strands in here. This is lung underneath, but because the plural surface is so thickened and it's probably all consolidated, we can't really see much of it, but that's very severe. It's actually very rare to see a few that much of fusion.
I've not hardly seen it at all. And then some weird and wonderful things. So, on the far left, we've got a full long lobe consolidation, which is probably got fluid and abscess material in there.
I've never seen anything like this, but it looks like the animal sort of walled off areas of that lung lobe, and it's probably sort of floculent material. When you see this sort of bright white speckles, That's because there's air floating in that. So, probably some kind of anaerobic bacterial thing going on.
And then again, this looks like a full lung lobe consolidation and abscessation. So, pretty nasty. OK, so that's the sort of interpretation of what you can see.
And I'm just gonna now go into how we measure and score lesions because, if we're going to be scanning a, a decent number of animals, we want to, of course, write down their numbers and then give them a score. So either they're going to be normal or not normal. And if they're not normal, how bad are they?
And this allows us to then make decisions, regarding, you know, what we do with them going forward. So there are several scoring systems which are developed and used. And if you sort of do some literature search and reading up into this, you will see that.
This is the most standardised and accepted one, which is by Teresa Olivet and is, probably the best one to use when you're starting. We tend to split it into two, so there's 56 scores, and, we split it into normal and not normal, basically. So if we start off on the, the normal side of things, so score zero would be lungs with literally nothing seen.
So no comet tails, no lesions, completely 100% normal, quite rare, but, that would be a score 0. Score 1 would be a few comet tails. So animal is normal, but you've seen a few comet tails, go to score one.
Score 2 would be you see small lesions slash bee lines, but the lesions are under 1 centimetre. So, we still consider this to be a normal animal. There's been a lot of studies done where they've looked at the effect of various sizes of lesions on animal parameters, and basically animals that have lesions under 1 centimetre do not seem to have any adverse effects on their growth rates, milk production.
Mortality, etc. So if the lesions are under 1 centimetre and the animal looks healthy, we don't generally need to worry about them, although it may be an animal that you mark as we check. Then we move into the, more abnormal.
So a score-free, and these animals are very likely to need treatment, and certainly would be marked as that normal. So score-free, one entirely consolidated. Score 42 lobes consolidated, score 53 lobes consolidated or more.
And so. The more scanning we've done, or I've done, the more I just tend to Stop worrying too much about whether there are 4 or 5, but just literally say there was a lesion under 1 centimetre or no lesion, it's normal, or there's a lesion over 1 centimetre, it's abnormal. And for the most part, that's really all you need.
You don't want to get too bogged down and worrying about the scores of the animals because generally what we're scanning animals for is to find out the prevalence of subclinical pneumonia in that, in that herd. We're not scanning to determine if an animal needs treatment or not, because that's not really a cost-effective thing to do. And we will talk more about that in a minute.
Just to help you, there's an app which was developed by Wisconsin called Calf Health scorer. You can download it from the App Store. I think about 3 pounds and you can put in the calf ID, the clinical score and the ultrasound score and it spits out a nice spreadsheet, which is a nice, easy way to collect the data.
So feel free to download and use that as required. And in terms of prognosis, people often ask about this. If you're seeing an animal which has a score 4 or above, so really two lung lobes or more consolidated, survivability drops quite considerably.
Those animals are not ones which I would recommend a farmer keeps for the, breeding slash milking herd. So that would be an animal that would be moved into the terminal herd. OK, and we get a lot of questions about OK, great.
I know how to do this, and it's all very interesting, but how do I actually use it as a service to my farmers to generate, income for the practise, but also to, improve, you know, animal health and welfare on farm. So we'll talk about that now. In the last 15 minutes.
So I would say, don't just do it on its own because it's all very nice and cool when you first start doing it, but the novelty soon will wear off and, actually, you need to make service out of it. So, most of the practises we've worked with have used it as part of a young stock club or young stock service where they incorporate us, with other activities based on the young stock to improve their health. So things like weighing the young stock, taking bloods, total proteins, vaccinations, etc.
We also produce or MSD Animal Health also produces tools called the calf Health Checklist or suckler herd performance checklist, and these are on-farm audit tools, so they can be taken onto the farm and used to audit all aspects of the calf health and management. And you can, how we've used the thoracic ultrasound is to go on farm. Do the checklist, scan the calves, get a percentage or prevalence of, of subclinical pneumonia.
So we say, OK, they had 30% of calves were scanned with subclinical pneumonia. The checklist score was 60 out of 100. We've suggested several improvements, such as Using, you know, bedding, bedding up the pens better, cleaning out the buckets better, using a vaccination, and we come back in 6 months, we run the checklist again.
We scan a new cohort of carbs and we see if they've improved their scores. We find out, we find that this is a much more motivating and Quantitative way of using them. So it, it means that the farmers are actually getting, you know, a value and they're seeing the benefit of the changes they're making.
Always follow up. You know, it needs to be something that you push and you make sure the farmer is engaged and follow up with, with them to ensure they're actually making those changes. Just to mention the checklists are available with paper or as an app.
So if you go on the app store and look up calf Health Checklist, you'll find it it's free to download. So several ways you can use it. The, the one I just described is probably the best, but, and, and this is this basically that again.
So finding out what is the actual BRD prevalence on farms, you can look at treatment rates, and but as we saw, farmers are not very good at always knowing which cars need treatment. So they might say, I only treated 5% of calves for pneumonia this year, and actually when you go and scan them, you find there's a whole subset of animals that weren't treated, but actually You know, we're we're still suffering with pneumonia. So it's important for the farmer to understand these animals, even though they haven't treated them or noticed them, are still causing, they're still draining the profits of the farm because they're not growing as well.
They won't produce as much milk and the lactation. They're more likely to die. So these animals do need dealing with.
And we can see here in this study that consolidation was seen in animals from 2 weeks of age, and the most sort of common age for severe, more severe consolidation is between the sort of 6 to 8 week period, and this makes sense to me because we know that the MDA is waning. So the maternity derived antibodies from the lostrum is waning around this time. They're being weaned, you know, it's a very stressful time in their lives, often getting procedures done to them.
So that their general immunity isn't going to be as good and they're more prone to suffering from from pneumonia at this time. So it's really important to make sure the farmer understands if they are seeing if you have got quite a lot of lung consolidation in animals of this age group, you really want to get your preventative measures in before that. So if they're considering intranasal vaccinations, say they want to get that in, you know, from week, the first week of life really.
This is a slightly different use for it, which some people definitely do. So you could actually scan your, a group of animals, probably post-weaning, which the farmer is intending to keep on as breeding heifers, and you can scan them all and, select the ones with the healthiest lungs to stay in the herd and, remove the ones that do not have healthy lungs, because they probably won't be useful for the breeding herd. So this, this could be, you know, helping the farmer for sort of future generations and, and it's quite a good way to use it.
And things, if you see things like this, you know, full lung lobe consolidation, or fusion, abscesses, these animals are not going to be as good. They're certainly not going to be, as productive breeding animals as ones with healthy lungs. And so they're ones that I would remove from the breeding herd.
There's a lot of papers, a lot of evidence to show that the larger the lung lesion, the worse the prognosis is, as you would expect, you know, anything over 1 centimetre, decreased average daily gain, anything over 3 centimetre, reduced first lactation milk production. Anything over 3 centimetre again, it decreased average daily gain. Anything over 6 centimetres starts to become quite serious, and that's increased mortality and cold risk.
So you can look at these animals, scan them, measure the lesions, and just say, well, this one had, you know, a lesion over 6 centimetres. I don't think you should keep this animal for your breeding herd. And then finally, you can do it as part of a project where you can manage respiratory disease on farm and look at the amount of antibiotics are being used, which is obviously a big hot topic at the moment.
If you have a farm where you think they're using too many antibiotics, you could certainly do, take a group of the animals and have a look at the, the lung lesions and then track them back to treatment records. So you can see if they are treating animals unnecessarily. And, you know, try and encourage the farmer to, improve their kind of detection of pneumonia.
Oh, yeah, and also calf rearing unit monitoring. So, we have seen this on, I've used it in this way as well, where we can look at, calves arriving on a rearing unit and Whether they're healthier and, and or sick. So if you can, particularly if you're able to know where they're coming from.
So if they're coming in, dribs and drabs or in groups from certain source farms, I've done this where I've scanned calves in the collection centre and, According to the source farm, given them their, their ultrasound grade, and then we can go back to the source farm and say, look, this group that you sent me were really unhealthy. Why is that? And maybe even encourage them to improve their practises or use a different source farm if they, if they're continually getting unhealthy animals and because it's not doing anyone any favours.
So yeah, this was, this project was very similar to that sort of idea. So here they scanned 800 veal calves on arrival. So these were coming from all different places and to the rearing farm.
This was done in Spain and they found that, a really decent proportion arrived with no lung lesions. Some are very severe lung lesions, so about 10%, and then 30% arrived with moderate lung lesions. And you can see here in this graph, I know it's quite busy, but On entry, the graph on the left is entry.
There were 9 farms, and you can see they've, they've scored them all and then showing the percentage of animals with the various lesions. So as an example, we can see far farm 5, they had about 50% of animals were healthy. And then they've got about 25% of animals with severe lung lesions and maybe another 25% with moderate lung lesions.
And then if we look after 7 days on the farm, Farm 5 are actually quite similar, so these animals haven't changed much. But if we look at farm 9, these all came in very healthy. And now look at them like after 7 days, they've got nearly 40% with severe lung lesions and another 20% with moderate lung lesions.
So these animals from farm 9 were probably very healthy, but naive, and then they came in and were mixed with animals from other farms, bringing all the diseases with them, and they've come down with disease. So this gives you quite a lot of information about each farm the animals are coming from and about the animals themselves. So, you know, this might be a good way to persuade farmers to say, look, actually, if you vaccinated all these animals, preferably before they arrived on your farm, but, even, you know, very close to arrival, that would really help to protect them against this, this mixing and, and, these animals that are coming in which are spreading disease to the others.
So, just in the last few minutes, gonna go for a case study that we did quite recently. So this was undertaken by Galloway veterinary group up in Scotland, and we had 7 dairy units of a similar size, and there were large dairy units wearing over about 4000 heifer calves between them. So big units, pretty much all indoors, similar management, very high health status, done in two phases in 2019.
So phase one, we scanned the cohort of calves, age 4 to 6 weeks on each farm, formed the MSD calf health checklist and recorded the recommendations as farmer. Phase two, we came back 3 months later, scanned new cohort of cars, 4 to 6 weeks, completed the checklist again, and recorded the improvement in score and actions taken by the farmer. And this is what we got.
So As I said, these are particularly healthy animals. So, it's unusual actually to find a farm where there's so many animals without lesions. So, phase one, we had, about 83% with no lung lesions and then about 15% with lung lesions and about 1.6% were treated by the farmer.
Phase two, we had a reduction in lung lesions by about 4%. And so, you know, this was really good. And we can see here that they also had a really, about 21% increase in checklist score.
So they basically implemented some improvements, in their farm management processes, and this had meant that their lung health had improved. And we can see the farms listed here. And so we've got the kind of data that we collected were percentage that were healthy, the percentage that had subclinical, and the percentage that were treated and noted to be treated by the farmer, and the checklist score out of 100.
And you can see here, you know, generally high levels of healthy animals and then the percentage of lung lesions, which is around 15, calf checklist score was about 63 when they were first, scanned. And then, in phase two, we can see basically every farm really improved their lung health score, except for this farm D, which ruined, I felt like ruined my statistics, but This farm D actually were vaccinating with an intranasal vaccine for pneumonia and then forgot in this cohort of cars and didn't do it. And you can see their, their healthy lung lesion percent went down from 77.
To 31, so they really messed up here and, and they were in deep trouble with their vet. And so that really does demonstrate that everything, you know, they hadn't changed anything else, that actually improved other, other aspects, but just by not vaccinating them, they'd really affected the lung health of those animals. The good news was they were really persuaded by, this data to start vaccinating again.
So they definitely saw the benefit in that. Then we also compared, the, farmer treatment rates to, the test. So we, we looked at the sensitivity and specificity, and we can see that their sensitivity was quite low, about 25%, which is, is, is sort of normal and it's been shown in other papers.
Specificity wasn't too bad. So farmers are generally, not overtreating, but equally, they're definitely not picking up every animal with lung lesions. And then we also benchmarked against the so we benchmark the test against the checklist score, and the good thing about this was what we could see is farms that had a high checklist score, so down this end.
So if the checklist is scored out of 100, if they had a high checklist score, they had a much lower lung lesion score. So farms with good, good calf management and, and, . Good processes were having generally healthier lungs, which, you know, sort of obvious, but it's actually quite limited evidence to show it.
So that, that really helped us to validate the checklist as a start and also demonstrate how useful thoracic ultrasound can be to measure, the health of the animals. And then we surveyed the farmers afterwards, so we sort of asked them about the project and how they found it. And they were very, sort of happy with how it went.
All 6 would recommend thoracic ultrasound to a fellow farmer, and, having seen the results. 5 out of 6 said they would be happy to pay for thoracic ultrasound as a regular chargeable service. 3 out of 6 are already using an intranasal pneumonia vaccine, and so they would continue, and 2 out of 3 that weren't vaccinating at the start of the project had started intranasal cough vaccination by the end.
So really work well to persuade farmers that pneumonia vaccination is a really good way to help prevent pneumonia and improve their lung health. So it worked out well, for the, for all the farmers that are in the project. Yeah, and that's just a quick summary of of it, how many we did and how many were normal and abnormal.
And this has also been published as a paper in the vet record last year. So if you're interested to read more, you can have a look and read, read about the study in full in this paper. So as a summary, building service around us, and there are several good ways to use it.
I think what we found to be the most useful is really using it to gain an idea of the actual prevalence of lung disease on the farm. So getting a percentage of animals that have lung lesions and using that as a kind of benchmark to then persuade the farmer to make some important changes. So whether you use the calf health checklist or not, and potentially in vaccination of other changes that could be made on the farm and then coming back on a regular basis, so every 6 months or so to scan a new group and see if the farmer was actually managed to make those changes and and the improvement in lung health that should result.
So I think when you want to get started with doing this, it's worth, firstly, you know, get used to doing the technique, have a practise, practise makes perfect. It really is an easy technique to learn. You know, once you've, once you've done a few, it becomes quite quick and easy.
Have a think about what opportunities you have, what sort of farms you want to use it on, whether you have a young stock club that you could use it as part of, the data that you want to use and how you want to use it, how are you going to market it? Are you going to charge? And if so, how much?
I, I would say that probably the people using it successfully tend to be running, using it in, in, as part of a young stock service where they're charging a monthly fee and it fits in with, with that young stock service. And then whether you use something like the calf health checklist to help you to kind of record those benchmarking changes. MSD actually have some useful tools to help with it as well.
So we have our cost calculators, and these can be if you speak to your MSD veterinary advisor or MSD account manager, you can get some copies of these, and they basically allow you to write down the calves and what scores they got, and then you can calculate on these graphs, how much that is costing the farmer in terms of in dairy, reduced milk lactation. And in beef reduced weight gain. So if they have, say, 30% of animals with lung lesions, you can plot it on this graph and say to the farmer, you'll be losing 2000 pounds a year because of that.
And that can really hit home in some farmers and they think, oh, well, actually, I could, you know, 2000 pounds a year, I can buy vaccination. So, you know, it means it's putting it into a cost-benefit analysis for them. And then if you're interested to learn more, we have some further resources.
So, myself and Jimmy Moore, who did, who I did the project with, run the bovine lung ultrasound Facebook page. So, there's lots of good resources on there. The MSD Animal Health Hub website, which is here.
And the website on Wisconsin University, they, they really started the whole test movement, as it were. So there's a lot of good stuff on their, on their website as well. And also the IMV imaging resources that there's some very useful information and also a webinar on there.
So be sure to check those out. So, all that remains to say is thank you for listening. I hope you found that useful.
And if you want more information, particularly around the MSD resources, then do feel free to contact your MSD account manager.