Hello and thank you for joining me for the topic of thoracic ultrasonography in the horse. I'd also like to thank the organisers for inviting me to participate in this webinar, . And mention that if you have any questions, you can reach out to me at vreef at vet.upenn.edu and I will be happy to try and answer them.
So, thoracic ultrasonography in the horse is a really useful technique, particularly because in the field, most practitioners are unable to take thoracic radiographs. It usually requires the horse. Coming into the hospital, and there are multiple small portable units of point of care units that you can use out in the field to get an idea about what's going on in the lung if you cult abnormalities on your physical examination.
And Basically, if you sculpt abnormalities on physical examination, it's highly likely that you're gonna see abnormalities on your ultrasonographic examination. And it could also show you ultrasonographic abnormalities that are clinically silent on auscultation. So, it's a pretty easy technique, to use.
It's gonna help you differentiate many different things that even radiographically, you can't differentiate, so you can differentiate compression of the lung when it's surrounded by fluid. From consolidation, you can tell if the lung is actually gelatinous and necrotic. You can identify an abscess that's forming or a soft tissue mass and maybe even infarction of the lung.
You can certainly identify pneumothorax and get an idea of its severity. You can identify the plural pathology, how much, effusion there is, what its character is, how high the fluid line is, if the cranul or caudal mediastinum is involved, and then you can use this information to formulate an initial prognosis and also to guide your treatment. So if you wanted to do thoracocentesis or a lung biopsy.
The ultrasound is very useful in helping you decide where exactly you might want to do that. So, To start off, the lung is really hyperchoic relative to the other soft tissue, and it casts an acoustic shadow which is the, these typical reverberation artefacts that you're seeing here in the upper right. And that's because the lung or air has a very low acoustic impedance relative to soft tissue.
And that's what causes that very strong reflection. So you wanna begin with a higher frequency transducer and then you're gonna decrease the frequency as needed to see deeper structures if there is a lot of pulmonary or plural pathology or a lot of effusion. And the higher frequency transducers are good to get a nice detail of the parietal pleural surfaces of the chest wall and the visceral pleural surface of the lung.
And as you can see in these two video loops, you wanna look at the chest through inhalation and exhalation. Many times areas will show up like in the video loop on the right, in, in one phase of respiration and not be visible in other phases of respiration. And that's, for two reasons.
One, the lung is moving and sometimes it moves behind the adjacent ribs, so you can't see deep to that rib. And the other reason Is that as they inhale, air can go out into some of the alveoli out in the periphery and they may mask a lesion that's just underneath the visceral pleural surface. And then you wanna be sure that the lung is gliding in real time, so you definitely wanna watch the horse breathe during inhalation and exhalation.
And if it doesn't seem to be moving, then you wanna make sure that that's not because the lung is adhered there. So you can make the horse take a deep breath while you're scanning, you know, you can hold off their nose or have them do a rebreathing bag exercise to get deeper breaths. So you can determine if the lung is adhered or if it's just from very shallow respiration.
We can assess the character of the pleural fluid. So you can describe it as anechoic, which usually means there's a transudate or a modified transudate. If it's more achoic, then there's more likely to be more cells and more protein, that's present in the fluid.
And if it's swirling at the COI, you have to think strongly about hemothorax or a large amount of red blood cells present in the fluid that are actually swirling with respiration and movement of the lung and the heart shadow. And then, of course, you can have a combination of these with fibrin, so you could just have a sheet or layer. Of fibrine on the lung surface or the parietal pleural surface.
You can have a spider web-like loculations, and then you can also have free gas that you can see in the pleural fluid, which is usually an indication of anaerobic pleural pneumonias. And you can see that Most of the anaerobic pleural pneumonias have free gas echoes mixing with the fluid, which is known as polymicrobullous effusion. And you can also get an estimate of like how much fluid is there by measuring from the point of the shoulder dorsally to get an idea of what kind of, return you might get if you do a thoracocentesis.
So if you actually just took a normal horse and put sterile saline in its chest, you have to put in about 5 litres before you can see it rise to the level of the point of the shoulder. So there's actually Quite a bit more fluid there than you can actually get out on thoracocentesis. As you go dorsal to the point of the shoulder, which is the DPOS, of course, you'll get more and more fluid out.
And some of the variation depends on obviously the size of the horse, as well as how much pulmonary pathology is present. If there's a lot of compression atleticis and not much consolidation, you'll get more fluid than if thick wedge-shaped pieces of consolidated lung are pushing the fluid level up higher. But that gives you a range of fluid, volumes that you can expect from doing a thoracocentesis.
So, initially, you may put the probe on the chest like you see here. And if you have very little or no lung sounds or large airway sounds that you're hearing in the ventral portion of the thorax, you're likely to see some images like this. So, here we have dorsal to the right and ventral to the left, and we have some aerated lung.
Here with these radiating comet tail artefacts which just are there because there's irregular aeration in the periphery of the lung there. And then we have a ventral tip of lung that's compressed and it's basically just floating in all that anechoic fluid. So that's typical of what you would see with compression alecticis and you can see that this says that on the left side of the thorax, this was taken in the 18th or excuse me, 8th intercostal space, and the fluid line was up to 15 centimetres above or dorsal to the point of the shoulder or proximal to the point of the shoulder is what that PPOS stands for.
On the right side in this horse, you again see . In this intercostal space, mostly compression aect. This is again, that tip of the lung floating in the fluid.
And we see this wavy membrane here that's also floating in the fluid. And that wavy membrane is the pericardial diaphragmatic ligament. So it's thicker, it typically undulates when there's a pleural effusion.
It's a normal structure that's present in every thorax. So, again, if you put sterile saline in a normal horse's chest, you would see this structure start to move around as the amount of fluid in the chest increases. So that's important to differentiate that from fibrine, because they look actually quite different, and I'll show you that later.
And then here's a, a fluid in the chest that's quite echoic and swirly as you can see on the bottom left. And this hyperchoic echo here. That's running all the way along the dorsal side is the lung, and then we've got this very echoic swirly fluid, that you can see both in that video as well as in this, this frozen frame, next to it.
So there's really several things to consider when you have a hemothorax. Infection usually is not one of them, so you're thinking about either neoplasia like hemangiosarcoma, and the postmortem picture there is typical appearance of hemangiosarcoma. That's actually on the pleura, and there's a rib.
That you can see right at the very bottom. Of this here. And this is a horse that has hemangiosarcoma.
So this is a large mass, solid tissue mass that's actually disrupting the rib in the right fifth intercostal space. There's this hypochoic area in the lung that happens to be hemangiosarcoma, but trauma like fractured ribs, diaphragmatic hernia, other types of thoracic trauma, penetrating wound. All of these could create hemothorax.
So then you have to try and determine what is the actual cause of the hemothorax, in this particular case. So, as I said, fractured ribs are one of the things that you have to consider. And neonatal falls, you're looking at, You know, the very young neonate, with rib fractures that are usually near the costochondral junction.
Multiple rib fractures, are usually present and they're usually, cranium. And the horses that have experienced trauma, you could obviously have a rib fracture that's anywhere, so. The horse on the left has a healing rib fracture in the 7th rib.
The left picture is a transverse view, so the rib should have this somewhat rounded appearance in each innercostal space or for each rib. And then the picture on the right there where the arrow is, is the long axis view of the same rib. So that's a callus associated with a rib fracture that originally had presented with hemothorax.
The horse on the right actually presented for a really unusual lameness, and nuclear centigraphy revealed this. Area of increased rate of pharmaceutical uptake here, that's actually in the first rib and performing an ultrasound examination, the first rib is quite challenging, but this is it, and there's still some irregular bone here consistent with Caus in that first rib. So this is a healing first rib fracture.
So, you always need to look at the ribs carefully, each one, if you've got acute hemothorax and you don't have a good reason for that. This is another example of thoracic trauma and what you can see with Injury to the lung. So this horse actually had a trailer accident, and you can see that.
On the right, that video loop shows aerated long. And then you have this very small compressed, collapsed ventral tip of the lung that's actually folding back on itself, and floating in that fluid, so that's a typical compression, pulmonary alectois. The tip of the lung is averted.
That usually happens because the fluid is very cellular like you would expect with the hemothorax. This scan was not taken immediately after the accident, so, some of the blood had been resorbed, so it's not as obvious as that last hemothorax. And then this ventral lung here is very abnormal.
It's hypochoic. It's swollen, so the actual ventral prankima is larger. In width or depth that it should be.
And there's this very prominent split in the prankima that's going from dorsal to ventral that you can see. And if you put colour on that, that's not a blood vessel and it's not a bronchus. The bronchus would have an achoic margins, and that's actually a split in the pulmonary pranma, although the, Actually, visceral pleural surface right here is intact, but that's consistent with a contusion to the, to the lung itself.
And then, of course, we can see fibrine in the fluid. So these are some examples of loculated fibrin. So in the video on the left, you can see a spider webby lacy appearance to the fibrine and that's very different from that thick membranous appearance that you had for the pericardial diaphragmatic ligament.
You can also see that during exhalation, This, these fibrine strands here that are attached to the axial surface of the lung are kind of stretched out, so they are, there is a a very loose adhesion here of this lung tip which is collapsed to the parietal pleural surface of the chest. And in these two frozen images you can see. The bottom one, again, another lacy loculated area between the parietal and visceral pleura with radiating comet tails in the periphery of the lung.
And in the one that's more dorsal, you can actually see that the lung, again with these radiating come tail artefacts is pulled out and is actually adhered to the parietal pleural surface there, which is why there's that raised or tented appearance to the lung. And you can also see this cavitated area. That's right below the arrow.
Right here. In the prankima. So it's more anechoic, with a lot of little hyperchoic echoes in it.
And so that's an abscess that's forming in that consolidated hepatized piece of lung, and that lung, as I said before, is adhered to the parietal pleural surface of the chest wall. And then we can see gas within that fibrine and the first thing that you typically see is gonna be hyperchoic echoes stuck to fibrine. So you can see all this lacy loculated fibrin here.
Again, compression alecticis of that ventral tip of lung, and then all these hyperchoic echoes that are casting these dirty shadows consistent with Gas. And so that tells you that you have an anaerobic pleural pneumonia, unless you have a penetrating thoracic wound. And you may also see that if you have a bronchioppleural fistula, but if you have a bronchialpleural fistula, you usually have Necrosis of the pulmonary parenchyma and anaerobic pneumonia, that's become a pleural pneumonia.
So, You gotta think anaerobes, and when you obtain a sample of this fluid culture for anaerobes, specifically, on the bottom right, You can see all these little short linear white echoes swirling around in a relatively anechoic fluid. Again, in a horse that has primarily compression that ectusis here with this ventral tip being squashed and contracted. And this is gas that's actually mixing freely with the fluid, which is called polymicrobullous fluid.
So in those instances, often there is really necrotic lungs somewhere in the thorax. It may be in an area that you can't visualise on the axial surface of the lung and or some bronchial pleural communication. You can also see that polymicrobullous fluid, in horses that actually have severe, necrotizing, pneumonia.
And so on the left, You can see that the visceral and parietal pleural surfaces. So here's a visceral pleural surface of the lung, which is this big hypochoic triangle with the hyperchoic rim around it, that's gas, that's stuck on fibrine on the outside of the lung, and you can also see those hyperchoic echoes along the irregular parietal pleural surface. Of the chest wall and that again is gas stuck on fibrine that's on the parietal pleural surface of the chest wall, and then you can see this very like bubbly.
Heteroechoic fluid, which is the polymicrobulu fluid. This piece of lung on the left is Larger than the typical wedge shape triangle, so That's a much more severe area of consolidation, and when you look on the Right, it's very difficult to kind of identify. You know, long on the right.
You see gas, quite a lot of gas stuck along the parietal pleural surface of the chest wall. You do see a flash of gas. With every respiratory movement like there and there and there, and that's actually dorsal gas, associated with a dorsal pneumothorax, that's moving in and out like a curtain.
So you have gas stuck on fibrine, you also have pneumothorax, and then you have a small wedge of lung, which is this little triangle that's coming in and out of view. And then you have all this material that's on the diaphragm with all these hyperchoic echoes, which is very difficult to Get a good handle on what's going on. There's definitely some long strands here that have bright white echoes that are probably fibrine, but there's also this vachoic thicker membrane, and this is actually the pericardio diaphragmatic ligament, but it's covered in gas, and this area behind it is the caudal mediastinum, and there's lots of gas back there.
And sometimes that's the first place you'll see gas in a severe anaerobic pneumonia. And then here is a more clearly visual visualised hydroneumothorax on the bottom left. There's no polymicrobullous fluid here.
There's just anechoic fluid. There's long underneath it with common tel artefacts. And right here is the dorsal pneumothorax that's moving with respiration, which is known as the curtain sign.
So that's fairly straightforward diagnosing pneumothorax when there's fluid. It's more challenging when fluid is not present. So keep in mind, dorsal is to the right and ventrals to the left.
So we have a dorsal air echo, and then with respiration, we see a different air echo that's moving back and forth. So this has to be the lung, this ventral air echo, and the dorsal air echo is free air in the chest, which is static associated with the dorsal pneumothorax, and there's a pulmonary contusion at that arrow, in the, in the lung and another horse with . Hydroneumothorax.
And then we could also identify when the lung just isn't moving freely against the chest wall. So in this case, we'd be likely to hear pleural friction rubs, and you can see that these are just two different examples of what I call a sticky lung, like when the horse takes a breath, instead of it sliding across the diaphragm and past the parietal pleural surface of the chest wall. It, it, you can see the diaphragm on the left here, and this is moving with the diaphragm, and it's barely moving relative to the parietal plural surface of the chest wall.
And again, this one here looks quite sticky, rather than getting that nice long excursion. So, The gliding sign is absent or it's abnormal, consistent with a, you know, dry pleuritus, small amounts of fibrine and with a lot, without a lot of effusion. And then we can have abscesses that are just in the plural space.
And so here's the bottom two loops are from the same horse, and you can see there are two different intercostal spaces. So in the 13th intercostal space in the bottom right, you can see the lung. It's moving with a diaphragm, so it's stuck there.
You can see a little anechoic pleural fluid and then you can see this walled off hypoechoic area in the plural space that contains tonnes of gas. And then if we go back one intercostal space, now we see the lung again deep to this abscess in the plural space, but now the lung is kind of, looks like it's stuck. To the abscess, so it's not moving freely separate from the abscess.
In the upper right, we see a very large pleural abscess. So here's the lung. Right here.
And this was like a 25 + centimetre Area containing echoic to hypoechoic, pretty homogeneous fluid, that turned out to be a a strepzo plural abscess. So you can get quite large pleural abscesses, but most of the time they are relatively small. So that's probably the largest one that I've ever seen.
So these radiating comet tail artefacts are common and they're indicative of early lung pathology, but they're really non-specific. So you can see these with interstitial pulmonary disease like a viral pneumonia or acute respiratory distress syndrome or interstitial disease like advanced equine asthma. You can see it with early pleural pneumonia, where there just isn't or pneumonia, excuse me, where there just isn't a large hypochoic area of pulmonary pranma that you can see, and you can see it with pulmonary edoema, for example.
So, These coalescing lines that you see here like this of pulmonary edoema versus just occasional or less frequent common tail artefacts makes you worry about like viral or interstitial disease or pulmonary edoema. So, if pulmonary edoema gets severe, you can actually get large hypoechoic areas in the pulmonaryranoma. So you can see that we can look deep on the bottom left to all those coalescing cometel artefacts, and we can see a hypoechoic area of lung pararanma right there.
And ventrally in the 6th intercostal space, we can also see a hypoechoic area of lung pran with a lot of hyperchoic gas echoes and also little pleural effusion, and this is from, these are both from this horse on the upper right, which has a flail caudal accessory leaf of the mitral valve and and came in an acute congestive left-sided congestive heart failure. So as I said, these changes in the comet tail artefacts, with, the ability to just see small hypochoic area of long underneath all these radiating comet tails. Is often an indication of early pneumonia or plural pneumonia.
And I forgot to say that the commonel artefact term is really sort of a dated term. It was in the literature for many, many, many years, and the new terminology is actually bee lines, or my favourite term is actually lung rockets. So I, I love calling them lung rockets.
So then we can look at the lung and determine like how severe is the consolidation. So as the errors get more hypochoic, The first thing that we're gonna see is air will still be present in the large airways like you see here. So this is the sonographic air bronchogram.
A in the large airways, fluid and cellular infiltrate in the adjacent lung. So this would be the equivalent of if you took radiographs, an air bron a radiographic air bronchogram, but it's a sonographic air bronchogram. Same in the horse on the bottom left, and you can also see in the horse on the bottom left.
That there's a a relatively anechoic pleally fusion, and there's small amounts of fibrine and one of those fibrin tags and more are causing the lung to be stuck to the diaphragm, which is right here. So we can see fluid go all the way around the lung between this parietal and visceral pleural surface, but not between the diaphragm and the lung. And then as the consolidation gets more severe, The airways will be filled with fluid, so that's a sonographic fluid bronchogram.
So that's a more severe form of consolidation than the air bronchogram cause now air is no longer even present in the larger airways. And then as we progress from there, we can have other things that happen. So you can have hepatization of the lung, which is your liver-like appearance, like you have on the bottom left.
Or you can have actually infarction or small areas of pulmonary thromboembolism, and because clot is a COA, the actual, portion of the lung that's affected, if you have a thromboboic event or infarction, is gonna appear more achoic, like you see on the bottom right versus the very anechoic triangular like shaped piece of hepatized lung. And the other thing I think you'll notice is this infarcted lung looks more swollen or rounded in appearance than the triangular shaped hepatized lung to the bottom left. And then we can put if the horse's breathing isn't too rapid, we can put colour.
On that hepatized portion of lung to try and get an idea about how much blood flow there is. And if you look at the upper left, you can see that there's much more blood flow in the hepatized lung than what you can see in the infarcted lung. Like we can see flow like in one vessel and the infarcted lung and like that's it.
The rest of the pranma doesn't seem to have any flow associated with it. And then we could also tell if the lung is necrotizing because it starts to lose its shape, and it gets almost gelatinous in appearance, and, and the prancuma gets very anechoic. So if you look at this loop on the left, There's very anechoic prankima here, lots of hyperchoic gas echoes, a hepatized piece of lung.
It becomes this anechoic because those areas are cavitating and becoming necrotic. So some of them may become an abscess, and some of them just may rupture into the plural space and the horse may develop a bronchopleural fistula. And in this case on the right, we have a very Triangular hepatized piece of lung, but it has all these tiny pinpoint areas of hyperchoic echoes, and that's consistent with free gas in the prankima or an anaerobic pneumonia.
So, if you did a BAL or transtracheal wash, you definitely want a culture for anaerobes. And then occasionally we'll see fungal pneumonias. And with fungal ammonias, we actually lose the normal appearance of the pulmonary prancuma and it starts to look more like a soft tissue mass or very disrupted prancuma, particularly as you see in that upper right.
And it, it looks like a granuloma, so this could be fungal pneumonia, it could be metastatic neoplasia, it could be, equine multinodular pulmonary fibrosis. And so most of the time you're gonna need a lung biopsy or cytology and culture or both to sort of sort out what's going on in this prankma. When the lung gets necrotic, it's gonna abscess.
So here we've got some examples of abscessation in the, in the horse with a large hypochoic. Bulging area in this long and some gas dorsally. So there's probably an anaerobic component here.
Here's a, a walled off abscess which is unusual cause abscess capsules are rarely present, completely containing gas. And here's some more typical like anechoic small areas of abscessation. We have to remember that we can in the fall, use ultrasound to look for Rotococcus equi abscesses, and these are just two examples.
They can have a variety of sonographic appearances and can, if there's bronchial communication can have air or if there's another secondary infection. So these are typical are equi abscesses and folds. And then we gotta remember that other things can cause abscesses, and keep in mind that fractured ribs can cause a pulmonary contusion, and then that area may, if the horse's bacteremic end up becoming secondarily infected.
So the rib fracture on the upper right, long axis view, short axis view of this healing rib fracture. Aerated lung, mostly plural abscess actually breaking out into the intercostal muscles, secondary to mostly plural and some pulmonary abscessation. And then this one is a horse that actually aspirated these two rose thorns and caused pulmonary and plural abscessation, and we were ultimately able to remove them through a thoracotomy.
Pretty unusual reason for pulmonary and pleural abscesses, I have to say. But her water trough was right next to some wild rose. And she had gone down to the water trough and then came back haemorrhaging from her nose and ultimately got this infection.
We can follow the resolution of the pulmonary abscess. So this is a dorsal caudal abscess and a thoroughbred racehorse that had EIPH. And so on the left, you can see the abscess when it was first diagnosed.
And on the right, you can see a bronchus kind of going through that and just a hypochoic area that's an area in the lung that's just scarred and not normally aerated and that horse went back racing successfully. If it ruptures into the pleura, you can end up with this polymicrobullous abscess like we see here. So, aerated lung, hypochoic area, which is actually the capsule of this abscess, dorsal gas cap here, these are two different horses.
And then here you can see the dorsal gas cap and this Very echoic polymicrobulu fluid with the capsule surrounding it. And this is a yearling that had this broncho pleural fistula and plural abscess, so, and actually went back racing successfully. So certainly, if you don't have those kind of things, the survival is better, and your treatment time is less, and your return to performance is better.
But with the management today, many horses are able to return successfully to performance, but the cost of treating a severe pleural pneumonia is high, so you can at least advise your clients about that. And then, you may have a horse, middle-aged horse, where you're suspicious of equine multinodu or pulmonary fibrosis, and it has a fairly characteristic appearance on ultrasound. You can easily biopsy these masses and you can see when you look at these masses, particularly the really hypochoic ones, you don't see anything that looks like pulmonary vasculature or bronchi, and you could put colour on to see that in fact, there aren't any, visible large vessels in that area.
And then, as you can see in this horse, you can go ahead and do a pulmonary biopsy. So we're doing a biopsy of the lung on the bottom right. You'll see that hyperchoic needle that goes into the lung parenchyma right there, there it's being withdrawn.
And the other great thing about ultrasound is after you've done this, and gotten your samples, you can go back and Quickly re-evaluate and see is there any evidence that you have pneumothorax or haemorrhage. And if you look at, this is the post biopsy scan and you can see that there is a little air in the chest right there, right over the area of the biopsy site. And you can see that air moving in and out, down, back down, back.
So there's a little focal pneumothorax, and we watched that for a while. It didn't get any worse, so that's, you know, that's another application of ultrasound if you choose to do, this, you can do follow up. Biopsy, or excuse me, follow-up scan after your biopsy to see the status of things.
Looking in the cranial mediastinum is a little tricky, so you can either take a high frequency probe like a microconvex. Get the horse to stand with its right leg forward and put that transducer in the 3rd innercostal space in front of the heart and angle towards the opposite shoulder, and you'll get this picture here. So we're on the right side in the 3rd intercostal space.
Here's the ventral tip of the lung, anechoic mostly fluid, some fibrine that you can see. This is the mediastinal septum as we're looking up to try and find the lung. Here's the lung on the left side.
I get a little bit of fibre on the left side, or you can put a larger Lower frequency convex transducer behind the scapularhumeral joint and again look in front of the heart, and you can get an image that way, but you have to use a deeper setting and the resolution's not as good. So you can see lots of fibrine in the mediastinum like over here on the right, excuse me, left, and you can see that this side, the right side is very different from the left side. So suggesting that there's a not a perforation in the mediastinal septum.
You can have images occasionally like this where there's just all this hypochoic fluid, and in this case, we did a, put a thora, did a thoracocentesis directly into this abscess. This is the Philae, it's 3 year old standardbred filly, and all this echoic purulent material came out, and that also was a strepzo abscess and she did very well. And then lastly, we can use it to look for neoplasia in the thorax.
And you're looking critically, not just for large masses in the cranium mediastinum, which is typical of lymphosarcoma, but we're gonna look at the pleura and the subplural area for disruption, irregularities, masses that don't move with respiration, so that they suggest that they're plural or subplural, and we also want to look to the adjacent area of the lung. This is an unusual case of lymphosarcoma in the horse involving the lung, and you can see that she has this marked distension of her bronchus, which is that a black tube surrounded by white. It's, it's huge.
The peribronchial area is very echoic, . And then we also have these small round hypochoic masses in the lung. So this actually is lymph, a form of lymphosarcoma, and these were all peribronchial neoplastic lymphocytes.
But that's the, the left picture is an unusual form of lymphosarcoma. It's far more common to have a horse present like this with a very large pleural effusion, often up here like 2025 centimetres dorsal to the point of the thorax, so you could get 50, 60 litres sometimes. When you scan, you just have pulmonary alecticis mostly and this huge pleural effusion.
You can see this horse has ventral edoema in the thorax because of all that pleural fluid, but also has a very prominent area in the caudal cervical lymph node region and you can see on the still on the scans that there's enlargement. Of the caudal cervical lymph nodes. Often it'll look like a big cluster of grapes.
And you can biopsy that as well as, take a sample of this pleural fluid. Most lymphosarcoma does exfoliate into the pleural fluid, so you should be able to get a diagnosis with cytology on the pleural fluid. You wanna submit cytology from both sides.
This is a media-style mass and one horse with a thoracic lympho sarcoma. But if you can't get it from the pleural fluid, you can usually get it from those, caudal cervical lymph nodes if they're involved. Most of the time, the fluid is yellow to sort of orangeish, but if you get hemorrhagic fluid like in this case here, you still need to think about neoplasia and look at all those buckets of pleural fluid we're, we're draining off this horse.
You can see on the bottom left that she's got a very large effusion. It's pretty a cox, so you know there's gotta be a lot of cells and protein in there. And then when you look at Her ventral lung tip and some of the intercostal spaces.
I'm not sure why this one's not playing. Let's see if we can get it to play. But you can see there's this hypo hypochoic area in the tip of the lung.
The pericardial diaphragmatic ligament is next to it. It's got all these little masses on it, so again, typical of lymphosarcoma. But you need the cytology to confirm that.
This is a standard bred. It's certainly more prevalent in standardbreds, than the other breeds, so that's another index of suspicion. This just shows two other mediastinal masses and horses with cranial mediastinal lymphosarcoma.
And you can biopsy that cranium mediastinal mass, and that's been reported about how to perform that with ultrasound guidance. The two pictures are showing on the left, scanning in that third intercostal space in the axilla and on the right scanning behind the scapular humeral joint. So this is scanning through the triceps muscle.
So, this area is further away from the skin surface versus here, this mass is much larger and maybe more clearly visualised, but you can certainly see the masses present in both cases. And then there's other things that you have to think about as far as neoplasia, so we gotta think about Hemangiosarcoma, that's, yeah, as I said before, gonna cause a hemorrhagic effusion. Often you will see these little small masses in the lung.
That correspond to those small, tumours which typically are scattered over the visceral pleural surface and in the lungs. So you can see from this retrospective study that the majority of cases of hemangiosarcoma do involve the lung and pleura, although, other areas like skeletal muscle and spleen are common. So we wanna look really critically at these masses, .
This is another larger mass in a horse with hemangiosarcoma and swirling fluid. Just an example of how many little masses can be there in the lung, and this is a horse with hemangiosarcoma in the rib, and that was the site of origination, the pathologist thought in that particular case. And then mesothelioma can cause large pleural effusions.
So again, you can have a really high fluid level. I would say that's less common than certainly lymphosarcoma is most common, then probably hemangio, then maybe mesothelioma. But you can definitely see mesotheliomas.
You can see this mass here is involving the pericardial diaphragmatic ligament, and it's much more heterogeneous than The homogeneous appearance of the lymphosarcoma mass or the Hemangiosarcoma. And as as with hemangiosarcoma and lymphosarcoma, the abdomen could be evolved as well. But with mesothelioma, it's just lining the mesothelial, you know, the surfaces of the body cavities, so peritoneal surface, plural surface.
So this is the cranial mediastinum with masses and then this hypochoic sort of Ill-defined soft tissue masses. Here, masses are layered along the parietal excuse me, parietal plural surfaces. And look at these, this is one of these two pairs of mules and look at this neoplastic infiltrate all throughout the pleural cavity.
Pretty impressive. So, again, you wanna critically look for those kind of masses. Cytology may be helpful in that instance.
Cytology and hemangiosarcoma of the fluid is, is not very helpful cause you just get blood, . And then you also have to consider carcinomatosis, which is metastatic disease from some sort of carcinoma, and that again can cause a very large pleural fusion that may be pretty cellular, as you can see here on the upper right. This actually usually is a productive, Fluid sample to get and look at cytologically, and you'll usually see neoplastic cells.
This is the cranomeostinum and this particular horse with carcinomatosis, but you can see that there's just masses everywhere. Here's a long Ventral portion of the thoracic cavity, back of one of the ribs, which is this mass that you can see right here. So, again, you would need cytology to help you like differentiate this from The other tumours, and then if the horse is grey, you have to consider melanomas and certainly melanomas can.
Metastasize to the lung and plural cavity and again tend to be Multiple masses, that sort of coalesce that can line the whole, plural or peritoneal surface. With melanoma, in particular, you know, you're always, if it's a grey horse, you're always kind of looking for masses elsewhere. And you can see this horse has a, a skeletal muscle is one of those elsewhere place.
As well as the parotid salivary gland. And this is the left pector muscle, and this is a melanoma here, this multiloculated or lobulate hypochoic mass, which you could aspirate to confirm that that's melanoma, but you still don't know until you evaluate the thorax that you've got melanoma in the thorax, but that would give you a high index of suspicion. And then lastly, primary pulmonary neoplasia, very rare, but it's gonna just completely disrupt the normal architecture in the lung, and you're gonna have a hard time identifying.
Bronchial structures or vessels, or if you do identify them, they're very disrupted, and as you can see here, there's basically no normal pulmonary parenchyma present in this particular horse. At last, I just wanna mention diaphragmatic hernia because certainly the structures of the abdomen. Can go into the thorax if you have a diaphragmatic hernia and usually do.
And you can have any abdominal structure present in the thoracic cavity. So on the bottom left, you have small intestine. It's still motile, the small intestine wall looks a little bit thicken, but you definitely have a lot of small intestine herniated into the right side of the thorax, dorsals on the right, and here's the diaphragm.
So this is in the thoracic cavity. On the left, like identifying large colon or stomach in the thoracic cavity can be more challenging. So it's really important to find the diaphragm, which usually is gonna be contracted and curled up ventrally.
And here is long, this hyperchoic echo here is the lung. And this is the thin wall of the colon. So in this case, there's large colon present in the left side of the chest, but you could just as well have stomach there in the left side of the thorax.
You can have spleen in the left side of the thorax spleen and liver. On the right side, you could have liver in the thoracic cavity, you can get small colon in there. So, Most of the abdominal structures, except the kidneys can actually end up in the thoracic cavity.
So definitely wanna still keep in mind that diaphragmatic hernia, can be present there in the thorax, . And you might find it as a surprise. So, I'm happy to entertain any questions on via email.
I thank you very much for your attention and coming to this presentation, and hope that you've enjoyed seeing pathology in the equine thorax with ultrasound. So with that, I will sign off. Thank you very much.