So, thank you very much for listening everyone. Today we're going to be going through ultrasound guided biopsy as well as some conversation on ocular ultrasound, the particular technique of that. With regards to a biopsy, we have to discuss what techniques are available and why some of them are appropriate in the horse and others are not at all.
With the majority of this conversation for this lecture, I'm going to be talking about biopsy of either visceral organs or of neoplasms rather than say, an abscess. The reason I say that is that fine needle aspirates are not appropriate, in equine patients in the vast majority of situations. The only time That I carve out that comment with is that abscesses can be very helpful and even melanomas as well to say that there is black tissue.
Obviously, with melanomas, then there is the one slight problem that you can have a more severe melanoma and the fine needle aspir would not give you the exact diagnosis from that point of view. So hand operated true cuts are very helpful. They're very easy to perform, but the one problem is that sometimes they are consistent in inconsistent in diseased tissue.
Part of that reason is that they are, they're not very powerful, and so they can bounce if the tissue is fibrous. For me, the spring loaded true cuts are the best. So you can have the semi-automatics, such as the, the other sort of true cuts that you can buy.
Again, I find them slightly inconsistent because they don't have the power to get through thick, fibrous tissue. For me, the biopsy guns, such as the Galini is the the sort of the gold standards that we can use. The problem is that it does come at a cost of around 400 or 500 pounds for the handle, but it does make life a lot, lot easier.
But how do any of these things work and this obviously been borrowed from the COC website to make it the the biopsy. But obviously the important thing when you're thinking about these biopsies is that the throw of the needle is beyond where you insert it. So when you're doing an ultrasound guided biopsy, remember that where you see the end of the tip of the needle is not where the biopsy will be taken.
Most of them, such as the true cut will throw about 3 to 4 centimetres beyond the end of the needle. So be aware of that if you're scanning and you can see a large blood vessel at the periphery of your vision. But what are the principles of biopsy?
For me, the first thing is to make sure that you've got adequate sedation. You don't want a horse jumping around that's going to make your life a lot more difficult. So generally I use ditomidine and buorphenol as a starting point, but if I have a very difficult case, then I will use dittomidine ACP and morphine to get them to stand a little bit more still during the whole process.
Then it's important to identify the site. So in this image here, we're going to be looking at the liver, and I'll continue the liver through the next couple of slides. And make sure that you're happy with what you're seeing, with what structures are around and what risks there are, and I'll go through the risks of each individual organ as we move forward.
Once you've identified the site, then you need to determine the depth of the biopsy that you're going to be performing. So in this image of the liver, we can see that the liver is central and highlighted and the right dorsal colon is below it. So obviously we don't want to be hitting the right dorsal colon.
Firstly, I gen I sort of eyeball this measurement, is the skin and the subcutaneous tissue because it does vary, as we all know, with obesity. So some of them will be up to 5 to 10 centimetres before you even get into the abdominal cavity. And then measure from any structure from the body wall to the structures that you're worried about.
So in this case it's a further 4 centimetres, but what's important is that in the vast majority of situations, you're going to be coming in at an angle rather than perpendicular to the skin, if you're doing an ultrasound guided biopsy. And for me, I don't see any reason why you should be performing a liver biopsy without the use of ultrasound in this day and age. I think if you do, then you are liable if there is a complication as to why you were not using ultrasound guided biopsy techniques.
In this situation, obviously, you now have a much larger amount of subcutaneous tissue to get through, but also you suddenly have a lot more scope for safety in, in this situation. The one thing to be aware of, it's not too easy to see in this image, but at the tip of the arrow in the bottom left of the screen are the main vessels going into the liver. So do be aware of those, but if you're getting 15 centimetres into that liver, you'll you'll be doing well with most true cut needles.
So once you have decided on your appropriate depth, you can make a note of that with your with your needles. If you are using a guide to on the probe of the ultrasound scanner, be aware that that will also increase the depth slightly. Once you've decided on your site, clip and scrub the area, so it's an aseptic preparation and infiltrate with local anaesthetic.
Now when doing a liver biopsy or any abdominal biopsy, to be honest, you will get subcutaneous and intramuscular levels, but it's very unlikely to get the peritoneum unless it's a very thin horse. So don't be surprised if there is a reaction as your your needle, your biopsy needle goes through the peritoneum. For me, I normally use a stab incision with a 15 blade, and so they're very small incisions and therefore don't need sutures.
The only time I do suture them is if they're going straight back into the field, with no possibility of keeping them nice and clean for 24 hours whilst that site closes. So as you can see in these images, I am using a biopsy guide and I do find them very, very helpful in things like livers and spleens when you are trying to, you're just going for a general area. I do find them slightly frustrating when I'm going for a very specific small area because they don't give you the ability to move the needle very easily.
They're, they're quite rigid based around the, the biopsy around the ultrasound probe itself. But in the early stages of doing these biopsies, it does make life a lot, lot easier and make sure that you are in the right place and not struggling with trying to guide between your left and your right hand. So what can be biopsied, and I think this is an important question because in small animals they biopsy a lot more than we do, and there's a few reasons for that.
But for me, most things can really be biopsied nowadays. Obviously with some caveats. Liver is very, very common, you know, we do that most weeks.
Kidneys, we do do occasionally as, as well as spleens. Intraabdominal masses are absolutely fine as long as you know what you're looking at and also that they are safe to approach, and the same with lymph nodes. There are some crazy people like Gunther van Loon who are doing the heart, but I think I would strongly recommend that you don't do that, in any situation as I am terrified at the thought of doing it.
So when we consider the liver, what else are we worried about? Because I think whenever you perform a biopsy, the most, two most important things that you need to consider are why are you doing it? So what are you going to do with the information, how are you going to interpret that?
And also what are the risks of it? Because if you don't understand the risks, then you don't know what you're trying to avoid or what you're trying to do. So when we consider the liver, it's very easy to biopsy the diaphragm and in some ways that's not the end of the world.
It's a very large structure and you will have to pass through it on, on a number of occasions. Intestine, you're sitting right next to the right dorsal colon, as well as the duodenum. So some slightly misguided or overextended biopsies will take a chunk of the intestine.
And in most situations, that isn't a problem. But I think you have to be very aware if you do do it, that you should cover these, these sources with antibacterials, antibiotics, sorry. Kidneys, I think, are very important because of the risk of bleeding, as is the spleen.
Lung, you do occasionally hear of people doing as you're having to shoot through a small window, but in most cases, again, you shouldn't be getting anywhere near the lung. Amazingly, on some of the histopathology we have been sent into the hospital to, to analyse, we have seen heart muscle on a liver biopsy, which is slightly terrifying. Obviously that's a left-sided approach rather than a right-sided approach, but it is something that is slightly terrifying.
So what are the risks, and this I think is of all biopsies, but particularly haemorrhage in this case is to do with the, the liver. Infection, so normally I cover them with a one off shot of penicillin due to concerns that the preparation or the probe may not be perfectly clean. I don't touch the probe anywhere near the biopsy site, but it is just a prophylaxis.
I always give them some non-steroidals as well to make sure that they don't have any signs of colic following this. Haemorrhage though is something that I think we discuss on a regular basis, and we do have to be aware of it. So, with severe liver disease, we know that there is a reduction in the production of clotting factors, and therefore a theoretical increased risk of haemorrhage.
And this is something that for a long time really limited the ability to take liver biopsies as people were scared to do so. But, John's in 2008 looked at this and found that in 33 cases that were biopsied, 58 had clotting abnormalities, 58%, sorry, and 12% of those biopsied showed some evidence of, of bleeding following it. But there was no association between those that had clotting abnormalities and bleeding, and no increased risk.
And of those that bled, there were no adverse events. So it really isn't too much of a risk and it's not something that would stop me ever performing a biopsy. That said, I always scan the abdomen and the liver following a biopsy.
To ensure that there is no bleeding before these horses are sent home. If there are any concerns, of which I've only ever had one, I keep them in overnight to make sure that they're doing fine. So how to avoid complications?
Obviously you're going to try and avoid any areas that have large blood vessels, and these two images are from the same horse, indicating that just by moving one rib space, you suddenly get a much safer view on the left hand side of this compared to the right hand side. And so really choosing your spot, that location is absolutely critical to success and really take your time, really think about it prior to starting to clip and prep. And also it's important to consider when not to take a biopsy.
And you know, I think if you genuinely have concerns, then don't take the biopsy because why are we taking it, as I've already said, what are we going to do with the information if this information is going to create a treatment protocol that is going to save this horse and it was going to die otherwise and absolutely crack on. But if you're doing it for academic interest or a definitive answer for the owner, then, really don't do it. So this was a case of a suspect hemangiosarcoma.
So you can see that mass within the liver. And in this case, I decided to elect not to biopsy because of the severity of the hemoabdomen. And really, it was not going to change the outcome of the disease process at all.
So when else not to biopsy in livers specifically? So hyddaid cysts leave them well alone, so that top picture is a very stereotypical hydaid cyst, a perfectly spherical black hole within the liver, and quite often you'll see marked numbers of them within the liver itself. In doing, if you do biopsy them, you're going to release metacyide, sorry if that's the wrong parasitism term.
It was never my forte. But you can increase the risk of repeat infections with them, whereas most hydactid cysts sit and don't cause any problems to the horse itself. Also, the hyperchoic starry night image that we're seeing in that bottom right, these mineralizations, whether they're from a bit of chronic active hepatitis or whether they're from parasitism that has moved around in an aberrant migration.
Most of these are often incidental. That said, they can reflect underlying pathology. So if you pick this scan up as an incidental, then don't do it, you know, if the blood work is completely normal.
If though the blood work is abnormal and you are scanning because of the the blood work, then take a biopsy and see what you can find. But the vast majority of these that I've ever done have come back as fairly unremarkable. So that's the liver, and I think the liver is probably one of the most common and the easiest organs to biopsy.
So I'd be very happy to, to do that on, on the vast majority of cases. So renal biopsies, we don't have too much of an indication in the equine patient to do this very often. The majority of the time, the renal disease we see is fairly acute onset secondary to non-steroidal or gentamicin toxicity, or as people are starting to use bisphosphonates more and more, we do see a bit more with those.
The only time that I think that it is useful to biopsy er really is when you're considering neoplasms to give a definitive prognosis, or when you could consider a nephrectomy of a unilateral renal disease. When performing a renal biopsy, I consider the medium to high risk er due to the severity of bleeding that can occur er because of the blood vessels in this. So, we do occasionally see colic following these biopsies and expect hematuria.
So do warn the owners that there will be bleeding following the kidney biopsy. So, you know, this video is just a nice one showing that you're trying to enter both through the cortex and into the medulla ideally. So, you know, my needle is just at the the capsule of the liver and then that throw is the bit that you can see going further on into it.
But it really is, as you can see in this bottom left picture, very important to assess the blood vessels within there there and make sure that you are trying to avoid the main renal arteries and things like that. That said, it is virtually impossible to miss all the blood vessels in the kidney cos there are so many. If there is bilateral disease, then you want to choose your right kidney if you can because it will be sitting against, or hopefully it will be sitting against the body wall.
Whereas your left kidney obviously will be sitting through the spleen. So if you are forced to do a left kidney biopsy, you must pass through the spleen, and for me it's really important that you test clotting profiles prior to doing this. Because the spleen is just a bag of blood, and if there are clotting disorders, then you have to take care.
Also remember that with the majority of kidney diseases, you're probably going to have a low PCV if it is truly chronic kidney disease and therefore, any bleeding will have slightly more serious consequences than if the, if it had a normal PCV. If though you are considering performing a left sided renal biopsy, then you should consider the use of transnosamic acid or any of these other aminocaruric acid or anything like that. This is just going to increase clot stability as they form and therefore hopefully decrease the risk of bleeding.
There are, there is a wide range of doses, if you look at the Beaver app, which is 5 to 25 milligrammes per kilogramme, as a bolus and then repeatedly sort of throughout, over every 4 to 6 hours. Now there are studies that show that 5 milligrammes per kilogramme seems to be an efficacious dose, so I normally sit in the 5 to 10 mg per 5 to 10 milligrammes per kilogramme dose. So when should you be careful with renal biopsies?
I think careful consideration should be applied when there is a hydronephrosis. So this image on the right hand side shows a kidney that is severely, is a severe hydronephrosis. And there's absolutely no point in biopsying that because if you're lucky, you might get a tiny bit of medulla, but you're more likely just going to go into the urine that's beyond it.
And what information is it going to gain? It's very unlikely that you're going to suddenly find an answer that's going to allow a treatment and therefore you're really assessing whether or not you should be doing a nephrectomy in that case. There's a huge risk of urine leakage following a biopsy because the pressure is quite high in one of these.
So do just be conscious of that, er, and I would never personally biopsy a a hydronephrosis. Renal stones are relatively common, in the equine patient. And then there's no point in even considering trying to biopsy them as they are rock solid, and also it's not going to change your treatment protocol.
So if you're getting the shadow that you're seeing in this bottom left picture, then it is a mineralization that is likely a stone. So generally avoid that. But what about masses?
And this is sort of a general discussion in this this image of whether or not you think you can do it. And I think this is very much skill dependent and should, you should critically appraise both your equipment and your skill set as to whether or not this is an appropriate biopsy for you. So in this situation, we can see that there is a mass in the sort of the axial aspect of the right kidney, and it's in this bottom left picture, approximately 2 by 2.5 centimetres in diameter.
So it's a very small mass and you're talking at a centimetre of 10 to 50, at a depth of 10 to 15 centimetres. Also, you've got to consider what do you have to pass through and what is beyond it. So in this case, you are going to pass right through the whole of the kidney, and therefore the risks involved in it.
But what we can see is that to the left and below the mass is where the renal arteries are, so we should be relatively safe from a bleeding perspective. But remember that the throw of the biopsy needle will go beyond the the mass and therefore could enter the tissue beyond which would be likely large intestine. In my, for me, I felt that this was a acceptable mass to try and biopsy, given the size.
I felt a 2.5 centimetre circle. I could get the needle into that, and also the location.
For me, also, the hopeful diagnosis is critical in this case because if this is something benign, then we can ignore it. If it is something neoplastic, then we need to perform a nephrectomy or chemotherapeutics. So it would absolutely in my opinion, change the outcome of the disease process and the treatment protocol.
Lung biopsies are an interesting kettle of fish for me. When we consider a consolidated lung, as in this bottom left picture, it is a very low risk procedure as long as you're not throwing the needle beyond the end of the consolidation. So for me, if you are worried about a mass within the lungs or you have a severe pneumonia that you need a direct sample from for culture, in which case you could use a fine needle aspirate, definitely.
Then these are very safe procedures. If, on the other hand, you're talking about an aerated lung as is in this top right picture, these are high risk for death and very high for hemoptysis. So in other words, coughing up blood.
Do warn the owners that that will likely occur, that they will cough blood and that they are likely, or there is a risk of dying. I, thankfully, touch wood, have not yet had one die following this, but I know a number of colleagues have. And the reason for that is, you know, with my terrible drawing here, is you don't know what is right below that surface.
Is it a load of lung tissue that is absolutely fine to biopsy? Or is there a large artery sitting 1 centimetre below that tissue right where your knee is gonna pass and you're going to lacerate it? So the only time I undertake a lung biopsy is when you have a severe REO or similar where you are trying to tell the owners whether or not this horse should be euthanized due to the severity of fibrosis within the the lung tissue.
Other, other than that, I don't see any reason to biopsy, and there are other ways you can biopsy via an endoscope, although it's not very efficacious. So next is your spleen, and again, for me, the risk is quite high. As I've already mentioned in the kidney section, I would always check your clotting profile first before performing this procedure.
So why are we doing it though? Again, we come back to that fundamental question whenever you're taking a biopsy of why are we doing it? For me, we can do splenectomies, although very rare in horses.
It is a surgery that is possible. So if you had neoplasms purely located within the spleen, then you could theoretically remove them. The problem is that the vast majority of splenic neoplasms in the horse are things like hemangiosarcomas, which have a very, very poor prognosis, compared to, say, lymphoma or something along those lines.
But that said, I have had a number of cases that were presented as neoplastic ultrasound scans, but then on biopsy have turned out to be abscessation, and therefore very treatable. So I definitely would consider doing that. So this scan that we is playing right now looks like a neoplastic.
Process, you know, it's infiltrating within the tissue and it's the same one as in the bottom left hand corner, but this was an abscess and thankfully that horse did very, very well, with a long course of antibiotic therapy. The one thing to say is that if you are trying to scan and see the sort of the slight changes in that architecture of the spleen, considering a possible hemangioma or hemangiosarcoma, the spleen doesn't exfoliate well, even with your large Gini needles. So don't be surprised if you try these processes and get a very frustrating histopathology report.
And finally, oh no, sorry, a couple more here, intraabdominal masses, again, care, because, you've got to consider what you think they are. So relatively safe in themselves, they're normally fairly discreet and hopefully if they're sitting against the body wall, nice and easy. If though, as in this bottom left picture, you consider this could be an abscess, so you know, this one actually, when you.
Went over and over with the ultrasound sound and you could see the tissue in the middle swirling. Then you've got to be really careful about your consideration. To get to that, I've got to go through the spleen and also the peritoneum.
So if I drag bacteria back through, I'm going to cause a splenic abscess. On the other hand, this top right picture was a large mash that was sitting ventrally turned out to be secondary to a wire penetrating the secum, but a biopsy meant that rather than it being a neoplastic process, which is going to have a hopeless prognosis, we found out it was fibrosis and able to go to surgery, remove the mass, and also remove the wire. So definitely worth considering and something that I've started doing more and more without too much fear.
Lymph nodes are easy to biopsy. I think they're probably one of the easiest things that we can biopsy, whether they are under the skin superficially or whether they are sort of up in the submandibular region. The More difficult ones are your mesenteric ones, unless they are very enlarged and sitting ventrally within the abdomen.
The problem with mesenteric lymph nodes is that they're not normally heavy enough to sit still when you try and stick a needle in them, so they can prove very frustrating to try and biopsy. Lymph nodes that are accessible in the horse are your submandibulars, your pre-scapulas, your prefemorals, even your external inguinal in some horses, although, obviously you're guddling around up between the back legs, so it can be quite dangerous. I think it's very helpful if you have a chronically enlarged lymph node to do this because are you dealing with a lymphoma, or are you dealing with a chronic infectious case that now just has a fibrotic mass?
So it is important, and these are ones that I wouldn't hesitate to perform a biopsy if I were worried. Thyroid is a bit of a tricky character. Because most of the time, the thyroid growths are non-functional.
So in other words, when you test your T3, T4, there's, it's going to be completely normal levels. But if you are concerned and it's a rapidly growing tumour and you are happy on ultrasound scan that it is solid and it is a tumour, then biopsy can be helpful because if it is a benign one, then you may wait until it becomes to a point where you need to do surgery to remove the mass from a size perspective. But also it it can give you a good idea if there is a more more malignant neoplasm.
Obviously, when biopsying, being very careful though, because the jugular and the artery are in very close proximity. So getting that angle along the length of the neck is what you're aiming for, not going perpendicular to the skin. When you consider things like cysts, sorry, then it's important that you don't biopsy them because you're not going to get anything.
So if you scan them and there's a big black hole in the middle of that thyroid, it is a cyst. Opening them and draining them as this was a case that we tried that, it doesn't work, they just refill. And these do need to be surgically removed, otherwise they continue to grow and become a problem just due to pressure in that area.
So, from a conclusion point of view, I think that biopsy is a highly useful technique in a number of medicine cases. And it is relatively easily approachable for many sites. That said, I think as an individual, you have to critically appraise both the, as I said, both the equipment and also your skill set to know whether or not you should be performing that biopsy and the facilities that are available.
In a hospital it's lovely because we can monitor anything and I keep all renal and all splenic biopsies in for at least 24 hours following the procedure, so we can monitor them. So they are not appropriate to be performed on a yard. Liver biopsies, I do feel they can be performed on a yard as long as the site and the area is clean and there are personnel there to keep a close eye on the horse following it.
And most importantly, you have to be aware of every risk of every procedure so that you can counsel the owner, but also so that you know how to avoid those risks. So ultrasound of the eye, slight change of tack here, so that we can have a think about a different technique. Ultrasound of the eye, I think, is a very underutilised modality.
I think most people are slightly scared to do it because it is unusual. And in a number of cases, actually, it's a very, very easy technique once you've had a good practise. And I think it's important to practise on horses that are relatively normal, so that you can get a good idea of what the eye should look like.
What are the indications, and I think assessment of the posterior segment is useful because obviously you can look at the posterior segment with a funding examination. But our equipment is fairly limited in the visibility of the vast majority of the posterior segment. Assessment of cataracts, you know, where, where is the cataracts within the lens?
Or if you've got an obstructive view of the ocular structure. So is there severe corneal edoema? Is there, as in this horrific bottom picture, you know, multiple conjunctival grafts that are going to completely remove any ability to see the back of the eye.
Also, assessment of any corneal lesions, is there a foreign body or something along those lines? And finally, any, any horse with exophthalmus should be ultrasound scanned, and I'll show you why in a bit. So how are we going to perform this ultrasound examination?
So it's important to have a 7.5 MHz or better transducer, as a minimum. If you have a curvilinear as a second probe, then fantastic because that can be used for some of the other structures.
The linear transducer is best unless the only time that you need a, either a microconvex or a curvy linear itself, then is when you're looking for a mass behind the eye. The linear transducers just don't have the penetration to get there. Transalpbr is the easiest and is pretty much the only way I do it in a horse, and using something such as a water-based lubricant such as KY will give you a good image.
Obviously, do not use alcohol or isopropyl or anything like that anywhere near the eye, because you could cause severe ulceration of the eye if you do that. Frans Corneal is possible, although I think of limited extra information in the horse. If you are to perform that, then obviously local anaesthetic using something such as not intrare again, sorry, .
It'll come back in a second on the next slide, but yeah, topical anaesthetic, sorry about that. And also marked sedation so that you don't have a horse that moves. Obviously small animals do that to increase the detail that you see, but I think in our cases it's not too, too often that you need it.
This is a list of useful resources that I, I find er particularly useful when I first started. Whitcombe did a Mary Beth Whitcombe did a fantastic AAP how-to session on, on using ocular abnormalities, ultrasound for ocular abnormalities and ultrasound. Otherwise, these are a couple of different studies that looked at different parts of the eye, and I think if you are going to do it, reading these just gives you a good background before you get to the client.
So, how to assess the ultraocular ultrasound. Obviously the eyelid is going to be closed, but I thought this was a slightly easier way to see it. It's really important that you assess the eye in two planes.
So firstly, I normally go from caudal to rostral with the linear probe in a vertical plane. I then rotate the probe at 90 degrees and go from dorsal to ventral. Making sure that you assess every part of the structure of the eye.
Now, I, normally look at different aspects of the eye at different stages, so the whole depth of the eye to start with and then also slightly more superficial ones at a different stage. And the reason for that is that, well, at least for my brain, I can't look at multiple different areas at once. Also you get far more detail with the ultrasound scanner if you bring the focus into shorter plane and to exactly where you're looking, rather than trying to look at the whole eye in one go.
So additional techniques that are going to make your, your ultrasound a lot easier. Firstly, the aricular palpable block is pretty imperative if you are having, or if you have a painful line. This is going to reduce the movement of the the upper eyelid, although not stop it completely.
So palpate the the oricular palpital nerve over that digmatic arch. Normally just flick your finger from rostral to caudal and you should feel that bundle under there. I normally give it a bit of a clean up and then inject a couple of mLs of local anaesthetic in a fan-like procedure and then massage it in.
As I said, this won't completely block your eyelid, but it should reduce the movement quite markedly. Sedation, as I've said, is absolutely essential if the eye is compromised, so you don't want the horse moving, but also in, unless the horse is absolutely perfect, you will need sedation. Just be aware of to twitches can make things very difficult.
Now, if all you're doing is ultrasound scanning, that's not the end of the world. But if you are going to be doing anything more invasive, then you should maybe consider morphine rather than bornil. So why wouldn't you do it?
What, what would be the indication to not stick a probe on the ultrasound scan, on the, on the eye? Is there a questionable structural integrity? So do you genuinely think that a severe ulcer is down to decime's membrane?
If you do consider that a possibility, then don't stick an ultrasound probe on there because to get good enough contact, you're going to have to put pressure on the eye, and therefore risk the integrity of the eye and risk a rupture. And that isn't something that you really want to be doing. Inappropriate equipment is another one.
Don't use a rectal probe. That's been places that it does not need to go when it's going near an eye. So don't use it.
Also, it doesn't have the detail that you need to assess an eye appropriately. Or if you are genuinely have a lack of confidence, again, practise on some nice normal horses and get your feel for what an eye should look like. But don't go straight in for the abnormal eye because there are lots of things that can look abnormal when they are normal, and I'll go through a few of those now.
So what can be assessed in the eye, there's a lot going on in this eye. So first of all, we can look at the cornea, we can assess the depth, the structural integrity, is there anything in there? Next we can look at the pupil.
Is the size of the pupil appropriate for the degree of light, dark, and so on? The lens itself, we can have a look and see if there is any cataracts in there or anything else that could explain why there's a problem. The iris itself, is there a melanoma?
Is there something structurally wrong with it? Although, honestly, even when I've had colobomas where there is a lack of an iris, it's amazingly difficult to scan that because of the very, very thin nature of an iris. It's actually normally easier to see with the naked eye.
The vitreous humour or gel is very important to assess, especially if you think you have a chronic uveitic episode. So you're going to be looking for detritus within that vitreous humour, remembering that some abnormalities are appropriate for age-related horses. Having a look at the retina, is it detached?
The optic nerve, really assessing that is, are there any abnormalities? Obviously, you can't look at some of the more precise things, but we're also going to look at the areas behind the eye. So what do they look like in reality?
So your cornea is going to look as two bright light, white lines, particularly the decima's membrane as the very bright white line, and we'll look at that in a little bit, or each bit of this in a little bit more detail. The pupil aperture is quite important to look at, so you can get a really nice view from the granuloridica on the dorsal aspect of the eye down to that ventral iris. The lens should present as two very bright white lines, with nothing in between.
And the Irish should have just these two thin branches with oscillary bodies on either side. The retina should be sitting nicely adherent to the to the back of the eye, whilst the optic nerve and optic disc should appear as quite a white structure that is a bit of a a Y shape as it enters the back of the eye. But what artefacts, so we can cause a lot of artefacts within the eye examination, ocular examination, so do be aware of that whenever you're performing these ultrasound scans.
So first and foremost, and the most common one is this abnormality that sort of looks like some crenulations along the top of the of the cornea. This is purely due to increased pressure on the eye. I'm not exactly sure what the changes within the cornea or within the ultrasound scan are that cause this, but it is a very, very common finding.
So if you see that, please don't think it's real, just release a little bit of pressure on your probe and you should be absolutely fine. Next, this isn't the perfect image of it, but if I just sort of remove those circles and then put them back there, you can see that there is some what looks like detritus sitting behind the the iris itself. And it appears that an acute angle of the ultrasound scanner of the ultrasound probe can lead to what appears to be vitreous debris, and can lead you to a diagnosis of ERU posterior ERU.
Be really careful of that because that is a very, very common artefact that you see in ocular examinations. If you are considering it as a reality, then bring your probe into multiple different planes and shoot from multiple different angles, and the vast majority of those vitriol debris areas will disappear. If you truly have vitreous debris, then you're far more likely to see it within the main, main chamber of of the eye itself.
Remember that the, there is often air between the eyelids and the cornea. So if you're seeing a little bit of air, as in this picture, then don't worry about that. What it's going to do is going to cause a bit of a problem with your image if it is sitting over an area that you're trying to investigate, but the vast majority of time it is not clinically significant whatsoever.
So whenever I do an examination, the first thing I do is measure the size of the globe. That's because obviously we want to know is one eye bigger than the other, especially if you're considering an exothalamus, or is there any indication that this could be a glaucomatous eye? So when doing this, you're gonna measure it from the front of the cornea to the front of the retina.
Now do it consistently between eyes, so measure left and right and compare them, and the vast majority of eyes will be in approximately the 40 millimetre region. Now remember that obviously if you're dealing with a small pony, it might be slightly smaller, but that's why we've got two eyes, so we can compare them directly. And again, remember, if you're seeing that crenulation along the cornea, you're likely causing compression and reducing the size of the globe dramatically.
So, be very, very careful that you are not compressing the eye when doing this measurement. As I said, assess bilaterally, so we can see that these two eyes are consistently exactly the same. They should have an identical depth and therefore, if there is an abnormality, measure a few times, make sure it is real, and if one is bigger than the other, then we're going to test for glaucoma, and do an intraocular pressure or look for some other reason for an increased globe size.
So, what are the, some of the indications for globeside? I've already mentioned primary glaucoma. You know, we don't see it too often within the horse, but we do get a number of cases and there are some treatments such as cosopt or acetazolamide, or, or even some sort of slightly more human ones that I op in that have a good effect on these eyes.
So if you have suspicion of glaucoma, the sooner you treat it, the better. Secondary glaucoma, I would say, is slightly more common, especially when you're dealing with a lot of polo ponies, you know, these horses do get bashed in the eye, and they get a lot of fibrin within the drainage angle. This leads to an inability to drain the eye and therefore increased pressure.
Or just severe trauma with debris, haemorrhage and things like that. So this image is one with an eye that's 42 centimetres, sorry, 42 millimetres in diameter. And it's purely because the eye has just got a huge amount of haemorrhage sitting within it.
So we've assessed the size of the globe, and now we're going to shorten our, our image, and we're going to have a look at the cornea. So it should be approximately 1 millimetre thick from the corneal membrane epithelium on the front to the decimate's membrane. It's quite useful to be able to assess in corneal edoema.
So this was one that was 1.7 millimetres thick. The image of the eye is actually the same eye.
And, you know, it gives you a very good idea of how severe it is and also can really help with monitoring progression of treatment. So quite often edematist eyes won't improve visually for a while, but we'll be actually improving thickness wise and so we'll, you know, you can compare that and give yourself a really good idea of success or not. Also, you're going to want to look for things like foreign bodies, stromal abscesses, and also you can assess ulcer depth if you're really worried.
I think more often than not, I assess ulcer depth with a slit beam lamp, and that gives you the best information and obviously your stain as well to see if it is a decimated membrane ulcer. But stromal abscesses are very important. Firstly, indirect ophthal ophthalmic examination is going to give you the vast majority of information you need.
So, you know, this one, the eye is one that was a stromal abscess that I dealt with, a chronic one you can see by the level of angiogenesis that's occurring around the eye. But this ultrasound image is, is the same eye showing that there is a pocket of purulent material within that cornea. And until you deal with that pocket of purulent material, it's not going to resolve.
And that is well beyond my scope skill set, but there are the ophthalmologists who can do flaps to remove that purulent material and therefore resolve these issues. And what you're going to be doing is assessing the assessing the location, because if it's throughout the cornea from, the epithelium stroma and SMA's membrane, then you're in trouble. If it's entering out the anterior chamber again, you're in trouble.
But also what you want to try and check is the anterior segment, the chamber, for any evidence of hype hyperpyion or hy femur, because that's going to again give you a really good prognostic guide. The one thing I would say is that a lot of stromal abscesses are associated with fungus and therefore have a very poor prognosis, irrespective of the surgical abilities of anyone. So again, counselling owners that that is likely going to be an unsuccessful case is sensible.
So when looking at your anterior chamber, we want to be looking at the depth. So it should be approximately 3 to 5 millimetres from the back of Decime's membrane to your iris or to your pupil, sorry, to your lens. It should be hypoechoic with no evidence of debris, and remember to scan right down into that ventral aspect of the anterior chamber because that's the most common area.
But what, what abnormalities can you see? So this one, these images on the right hand side are are what appear to be hyperpyion, but if you have a look at them, they're very hemorrhagic and the image on the left hand side is actually the same eye earlier in the treatment process. This horse was one with lymphoma, and this was a large conglomerate of abnormal white lymph lymphoma cells sitting in that ventral aspect of the anterior chamber.
Also seen very commonly in als with sepsis. So, you know, I always check my al eyes just with direct ophthalmoscope, ophthal ophthalmological investigation, but I will ultrasound them as well if I am concerned. And in severe ER usually you're going to start to see some debris sitting within that anterior chamber.
So it is, although a very small area, it is important to really investigate it very, very carefully. For people with the right equipment, which I don't think any normal person would have only a few places like Lee Hurst do, you can actually measure the drainage angle as an indication of equine recurrence, sorry, for glaucoma as well. But as I say, that is a very specialist technique and not one that is available to the majority of us.
So one of the biggest times you start to see anterior chamber abnormalities is trauma or foreign bodies. So this image shows a foreign body that has penetrated through the cornea and is now sitting within the anterior chamber with a chunk of fibrin attached to it. And that really gives you a good idea that, you know, this, what looks like just an ulcer and some edoema is probably not going to heal without any surgical intervention because that foreign body is going to continuously cause a problem.
The other, oh sorry, the video there just to show it a little bit more, obviously. The other is a blunt force trauma. So this eye on the bottom right was one that was presented following a polo match and you can see where the the mallet sort of hits the centre of the eye, leading to a huge amount of fibrin deposition, and a whole another level of problems that we'll go into in another slide.
So with regards to your iris, for your routine assessment, the granuloridica or corpora Niagara, should be sitting on your dorsal aspect of your iris, but do remember that a number of horses will have a degree of granuloridica tissue on the ventral aspect of the iris as well. So that's, that's the granular retiate there. The people aperture for me is, is one of the things that we're really going to assess because particularly, you know, if you think in this bottom left image, likely this horse has some edoema in the eye, you're not going to be able to assess if that iris is dilated or not.
So you can really see if there is meiosis, which there is severely in this case, or a nicely dilated eye with my midriacis here. So I do that to assess whether or not my atropine therapy has been appropriate, and if not, if we've still got meiosis in the face of appropriate atropine therapy to increase the treatment protocol to even every couple of hours in some severe cases. If you are increasing your frequency of atropine administration, please monitor the contralateral eye to make sure that that doesn't become severely dilated and therefore indicating systemic effects of the atropine.
But what about iris abnormalities? To be honest, the main one that you're going to be talking about is melanomas or cysts. You do sometimes, as I see, say things like collabboma or idial degeneration in severe cases, but they're very difficult to assess with ultrasound in my experience.
So this image in the top right, how do we know if it's a melanoma or a cyst? You know, they both present often as a very smooth spherical mass. Often melanomas will present with a slightly more textured, textured architecture to it.
But what we can see is that in this video, you can see the the the cyst coming and going, and it's this very thin walled with a hypoechoic centre that's been highlighted with the circle in the bottom right hand corner. With cysts, they are generally benign, unless they dislocate from the iris and they can float around causing problems and spook the horse. If though you do want to treat them, then laser therapy is possible to ablate them and, and rupture them, and then normally once that's done, they go away and they don't come back.
Obviously, melanomas are slightly more concerning, so these will, as I said, present often like a cyst, but have a slightly more textured arc textured surface to them. But on ultrasound examination, you're going to see this mass as a a solid tissue that will not appear like a cyst at all. From a prognosis point of view, then these are slightly more guarded because they will continue to grow, and they will continue to cause a problem over the horse's life.
Most of the time until they start touching the cornea, they don't cause any problems, but once they start touching the decimate's membrane, then they cause normally edoema and actually can cause ulceration as well, at which stage there's very little that can be done. I've talked to a few ophthalmologists and most of them are terrified of removing them because they don't do very well in horses, so, surgery is not really an option. The lens is something else that we can easily assess, so it should be anechoic, with very little, just those two, very obvious lines on the, anterior and posterior aspect of it, and should be around 10 to 15 millimetres in depth.
There are lots of different diagnoses for cataracts with incipient cataracts only taking about 5 or less percent of the lens up, immatures at 5 to 95% and matures at greater than 95% of the lens. Really old hypermature cataracts can actually lead to lens shrinkage away from the iris and the cillary bodies. So don't be surprised by that in some of the older horses.
And intramescent cataract can lead to an increased lens size and dilation of that lens itself. So what we look for in the lens is, you know, this is the same horse, it's quite difficult to see, but you can see there's just increased ecogenicity. So we've got the, the posterior line sitting here, we've probably got an anterior line sitting along the top.
And all this sort of tissue here is the abnormal cataracts within the eye. And this one was this eye here where we can see these few little dots, and we can see that it's actually a little bit more severe than you would expect. This is a more normal eye with your two hyperchoic lines.
So the other thing is this, this is the eye that we I presented earlier, and we can see that if we go back to this one, we've got this lovely presentation of your two cillary bodies here and here with the lens sitting right in the middle. When we look at this eye, obviously you've got a large amount of fibrin sitting within the anterior chamber, and you've got a lens sitting here with no apparent association with any of the iris or any other normal structures. So this eye had completely displaced its retina, sorry, it's its lens, and therefore was never going to be a functional eye again, but we did save it because it was a polo pony and they need to have two eyes.
So vitreous humour is something that is also very important to assess, and obviously, you know, these two eyes present why you can't have a look at the vitreous humour in, in the vast majority of horses. You know, the, the lens is very small, unless you dilate it or there's corneal edoema that stops you having a look at it. It should be around 15 to 20 millimetres in depth and should be absolutely clear.
As I've already mentioned, it's easy to have er evidence of sorry. Of vitriol debris around the iris which are artifactual. But in this case, you can see all of this tissue here, this is haemorrhage and this is abnormality.
This is obviously an extreme case, but you will see large amounts of protein deposition within the vitreous if you have equine recurrent UVitis, especially if you're dealing with the posterior ERUs that you see coming over from the, the continent on occasion. Now, when looking at the back of the eye, you need to assess the retina, and it should be an anechoic structure, about 2 to 3 millimetres in, in size. And.
The, there's often fat on either side of your optic nerve, which is sitting here. So don't be surprised if you get these hyper-echoic fatty areas surrounding your optic nerve. You do on occasion get retinal masses.
So this is a an image that says that looks slightly abnormal, and it's just that little lip of a mass sitting here. And also we can see a mass sitting in that yellow circle. The problem with these is that the vast majority of them are benign, but there are some that can penetrate deeper into the, extraocular tissues.
So with these ones, I recommend repeat ultrasound scanning over, every 6 months, ideally to monitor the size of that mass and ensure it doesn't grow and require any nucleation centration of all the tissues around the eye. More often than not though, your biggest concern, these are care of Andy Durham, is that you're trying to assess for a retinal detachment because that's your biggest concern. Is this eye functional or not in a trauma?
If you're getting that stereotypical gold wing picture of that bottom left picture, then that is a, a sure sign that you've got retinal detachment. And you can theoretically leave the eye in place if you, if you wanted to, but you will in the end get micro ophthalmia, ophthalmia as the eye slowly degenerates. So if you do see that, then tell the owners that the most likely thing or the best thing to do is to do an initiation.
When assessing for a mass, so if you have an ex ophthalmus, then you can do a couple of things. One is to use a curvy linear probe or even a microconvex, and assess from the transpo people view, and you will get a good idea of some masses sitting caudal to the eye. You can also use a microconvex in the fossa of the eye to look down or in some cases, as I, I learned recently, you can scan from underneath his facial crest and look up into the the posterior section of the eye.
It is very helpful to do this, but the one thing is if you see a mass behind the eye, then really recommend that you do a CT examination. This is an image from a horse that we recently had very mild ex ophthalmus that I I saw, and I could see a 4 centimetre mass on my ultrasound examination. I recommended a CT based on the history, and it had this mass that was infiltrating throughout the sinuses into the ethmoids and looked like it was going to go into the cavernum of the brain as well.
So in that case, you know, this one had a hopeless prognosis and nutriation was going to be of, of no help at all. I think it's important to try and look at your orbit. It's very difficult with ultrasound examination of the eye, but do have a look at it, because if you are considering a neoplastic mass, then we need to make sure that the bony structures are smooth.
If you think there's a squamous cell chima, carcinoma or lymphoma, then normally that bony structure will appear very rough on ultrasound and on palpation. And if you are concerned about that, then again, a CT should be performed to fully assess any further structures behind the eye. So in conclusion for your ocular examination, it is, in my opinion, essential for a full ophthalmic examination following your direct and indirect ophthalmic examinations.
It's the only way to assess the eye fully when the cornea is obscured, whether that's due to severe edoema or trauma or conjunctial grafts. And it is an excellent prognostic indicator for function of the eye. In practise hands, it is very easy to perform, although it's slightly scary when you first start doing it because you can get so many different artefacts.
But practise on normal eyes for that very reason. And I think the most important thing is to be gentle with the eye, because most artefacts are caused by increased pressure being placed on the eye. Good luck with any of these ultrasound, guided biopsies or ocular examination, and I hope this has helped.
Thank you very much.
