Thank you very much for Sophia. Yeah, so I'm going to, present a, a lecture today on modern upper airway diagnostic and diagnostics and treatments, that we utilise in the horse and is always the way with these talks we'll start with just a little bit of an anatomy refresher. And the anatomy that I'm gonna discuss is basically the endoscopic anatomy of the upper airway, which is basically what we are all most familiar with.
So endoscopically, this is what the upper airway generally looks like, or certainly the, towards the larynx looks like, and the important structures that we need to be aware of, and certainly we'll discussed many times in this talk. First of all, one is the, bilaterally paired ytinoid cartilages, either side, you can see in this particular picture here, these are fully abducted, out of the way of the airway. The important, open space that we need to try and maintain, or, or more importantly, the horse needs to try and maintain, is the trachea, or the windpipe, so the big black hole in the middle, and anything that's getting in the way of that is potentially going to be causing the horse a problem.
Pharyngeal walls or nasopharyngeal walls, as they're often referred to, surround the larynx, more rostral to the larynx, and we can see these all around, the airway. Vocal folds, are particularly important, both from a, disease point of view and the importance to the horse, because they, are exactly what they say. They are the vocal folds, they are the, the, piece of anatomy that allows the horse to communicate, with its colleagues in the fields.
These are found just below, the erytinoid cartilages. The ventricle is a structure, a blind ending structure just, below, or more importantly, more lateral to the vocal folds. And it's basically a sack of tissue, that can potentially fill with air and potentially billow, as we'll see in some of the, some of the videos later on.
The epiglottis is the rostral extension of the larynx. It's the rostral cartilage that extends from the larynx and is very, very important, along with the erytinoid cartilages in closing the airway and preventing food and liquids from entering the trachea and pretty much going down the wrong way, as we tend to call it in humans. .
Connecting the epiglottis to the erytinoid is the aptly titled Are epiglottic folds. And these are structures that traverse the side of the larynx, and they are equally as important and can cause problems. And the other big cause of potential problems in the horse is the soft palate, and we can see in this slightly cordially placed scope position, you can see the edges of the soft palates, and that disappears underneath the epiglottis.
So that's a quick run through of the anatomy of the upper airway, as I say, from an endoscopic point of view. We'll move on to the clinical signs, and these are the clinical signs of upper airway disease, and these are the the ways in which horses will be presented to us as veterinary surgeons. Respiratory noise is one of the most common reasons why the horse is presented for further investigation.
The noises can vary, from, gurgles, whistles, exaggerated what we would call normal noises. And certainly when the clinician is presented with a history of noise, you have to be very careful who is reporting the noise, how often is it heard, when is it heard, and Various things that can give you a few clues and indications as to what's going on. And certainly, working with racehorses, respiratory noise is a really good excuse that's often given by a jockey to a, to a trainer when they come in, and they've not particularly had a good race.
You often hear them say, oh, it's making a bad noise. It's winds wrong. And that's often something that we experience.
Poor performance, is probably more important in competition horses. Respiratory noise is one thing if the horse is still winning races or getting around across country in adequate times, and that's not a problem, but if it is affecting the performance, and in some severe forms of these diseases, performance is significantly affected, that is in Incredibly important. And of course, this is subjective, because performance depends upon the use of the horse.
A horse not winning a race is performing poorly in the eyes of one trainer, but it could have finished second and equally so, a horse performing poorly in a dressar test might not be related to its upper airway, despite the fact it could be making noise. We often find a combination of the two. We often find a combination of respiratory noise and poor performance, and that's certainly the most rewarding, clinical signs that we're dealing with as clinicians.
And of course, the other clinical signs are, or the other clinical presentations, more importantly, the courses are presented for further investigation, is pre-purchase endoscopy. Especially with racehorses and especially with sales, vetting of sports horses, upper endoscopy, is performed in, pretty much as a routine in, thoroughbred, vetting, pre-purchase examinations, and any abnormalities that are seen there potentially will require that horse to have a further investigation. So the clinical examination of the horse, pretty much starts with the general clinical examination.
Auscultation of the chest is important to check that we're potentially not dealing with the lower respiratory tract, problem. Certainly they can be related, and can, of course, be confused with upper airway problems and vice versa, of course. Palpating the larynx and the trachea is particularly important, palpating the trachea for any abnormalities, and palpating the larynx equally for any developmental congenital abnormalities, any abnormal shapes, and of course, palpating the cricorretinoidus dorsalis or CAD muscle, on the dorsal aspect of the larynx is something.
It would be encouraged for anybody doing a vetting of the horse, especially a large horse and a race horse. It's, it's easy to appreciate in severe cases of recurrent laryngeal neuropathy that will come on to more detail. It's easy to appreciate the lack of the CAD muscle.
You can feel the muscular process. And as with any of these clinical, clinical palpation. Of the horse, it's good to compare one side to the, to the other.
And as I say, in certain cases of recurrent laryngeal neuropathy, you will notice a significant difference, from one side to the other. And equally palpating the larynx for any abnormalities, any unusual, gaps between the, between the laryngeal cartilages is something important to do, in the early stages. Any horse that is reported as having a respiratory noise, and the first thing to do is to listen to it and listen to it working.
It's the, essential thing to do is to get the horse cancering, that in some cases, is easier said than done, especially in youngsters. But once you get that horse cancering and you get it's breathing synchronised as one breath per, per stride, you can really hear and work out which is inspiratory. So, inspiratory noises will be as the head is, sorry, inspiratory noises will be made as the head is coming upwards, and expiratory as the head is going downwards.
And obviously you can keep an eye on the nostrils as well to work out whether you're dealing with an inspiratory or an expiratory, noise. And, as I say, lunging in an arena, and as you've seen, lunging in a, arena or lunging ring, is a useful, useful thing to do, in these cases. Of course, if the horse is only making a noise when it's working, go up and listen to the horse working, and do a wind test, as we call it, of the horse working up on the gallops, and of course, listen to the horse being ridden in an arena, if that's its normal job.
Listen to it, work it, and work the horse. As it normally is work, there is no point in galloping a dressage horse up the gallops, if that's not what it normally does. And of course, it's not going to make the noise, potentially at those stages, and equally so, there's no, no point in riding a racehorse around an arena, hoping that on Make the noise in every situation, that isn't the case.
And there are certain things, especially in some sports forces, certain manoeuvres and equitational manoeuvres that can be done that will induce the noise, and these are important, and it's important to to make sure that those are replicated in the clinical examination. Following on from that, the examination of the horse, externally, our first port of call is normally a resting endoscopic examination of the horse, and we've seen this picture already. And basically using either a video endoscope, or, or a fibre scope, depending on what you have available.
Both are particularly useful for this and absolutely, fine for use in these cases. If we're suspecting and pretty much in any case, for the initial examination is ideally done on sedated. Sedatives as we know, as we know, have a massive effect on all muscles in the horse, and there is arguably a significant effect on the upper respiratory tract musculature, in the sedated horse.
So certainly, ideally do not sedate the horses. Obviously in yearlings and to Old horses, this can present a problem. But ideally, examine them unsedated.
The use of a twitch, neck and no switches can be useful. And no switches can either be provided by hand or using an external device, whichever the operator feels more comfortable with, but obviously always taking care with use of the twitch, both for operators and for your scope as well, you can quite easily damage your scope with a twitch. Convention tells us that we should use the right nostril.
It doesn't really matter, but that's what we tend to use. And that gives us this conventional picture that is slightly skewed to one side, but that seems to be what most people are used to, and certainly for sales in thoroughbreds, the right nostril is the nostril that is used. This is basically what we see in most cases.
This is the horse at rest, so you can see good synchronous movements of both of those erytino cartilageges closing. Closing down here to protect the air and then opening up nicely. These are pretty symmetrical opening up, fully opening up.
You can see on this horse here, there's two red marks on either side of the medial walls of the erytinoid cartilages there, that's where the, the, the endoscope has been passed down into the trachea and the erytinoid cartilages have closed over the endoscope, causing a little abrasion there from first examining the trachea. In some cases, you will not be able to get those written on cartilages to fully abduct. The horse will be relaxed, and you can't see full abduction.
And certainly, if you've got an asymmetry there, if that left side of the, the, the larynx, the erythtinoid cartridges, is not quite doing what you want it to do and not quite abducting, you need to see whether it's going to be able to do that. One potential is to occlude the airway. Excuse me.
So, the operator holding the endoscope, then closes both nostrils, giving the horse more to work against as it's breathing, and then as they're released, the big inspiratory, inspiratory breath, will then hopefully allow you to see those erytinoid cartridges fully abducted. The other possibility that you can do, and the other thing that we often do is induce swallowing. Either by using the flushed mechanism on a scope, if you have one attached, or if not, passing some fluid down the biopsy channel of a fibre or videoscope, putting some water, into the upper airway, inducing a swallowing event, and then after the swallow is completed, you should see fullerytinoid abduction.
The other thing that you can do as well is lunge the horse, and basically examine it straight away, lunge it or exercise, it doesn't matter what you do with it, really, but basically, any form of exercise, exercise the horse then examine it immediately afterwards. And as it's taking those recovery breaths, the erytinoid cartilages should be fully abducting at that point. So resting endoscopic examination can give you an idea of what's going on.
Certainly you can diagnose some things as we'll come to shortly, but it can also be misleading and the line papers. That were produced from the Bristol, group, showed that 51% of horses presented for investigation appeared normal at rest, which is not surprising. However, what is more worrying is 57% of these then went on to show a problem at exercise when they were examined on a high-speed treadmill, which is worrying.
. Especially if you're relying on resting endoscopic examination, and 54% of horses had a different problem at exercise than was suspected at rest. So horses that were examined and you thought this is a larynx, then goes on, the larynx is fine that displaces its palate, and equally so. Pallatal problems at rest, can often resolve at exercise and then you'll find that you've got a laryngeal problem going on at exercise.
So resting endoscopic examination is essential, it's important, and you can diagnose some things, but it is not the be all and end all. As I say, dorsal displacement of the soft palate is something that you will see. You will see it often, you can induce it with swallowing, you can get rid of it with swallowing, and you will often see it when you pass the scope into a horse, and you will see this intermittently come and go.
However, as we've said previously, there's no certainty that this will occur at exercise and the previously mentioned paper showing that you will often get false negatives and false positives, as a result of resting endoscopic examination. Permanent DDSP is obviously something, different kettle of fish altogether, but it's equally very, very rare, but I think most clinicians would, not want to diagnose permanent DDSP without seeing the horse exercising, at first, so. Moving on, laryngeal collapse, or recurrent laryngeal neuropathy.
This is basically what we see. It's often the left side of the, the larynx that's affected, and the left recurrent laryngeal nerve is the longest nerve in the body, as we all remember from university, and certainly that seems to take a hit. During the development of the horse, causing a problem, causing atrophy of the cricoretinoidus dorsalis muscle, the CAD, and the other muscles as well as we'll come on to see when we look at some of the diagnostic techniques, the CAL muscle, the vocalis muscle, all can be innovated and affected by recurrent laryngeal neuropathy.
This is what we see at rest, but there is then the potential that this may abduct at exercise. We certainly see some pretty severe, larynxes in horses that will actually abduct and exercise. It's also important to remember what the horse is to be used for, because if the horse has a poor larynx at rest, but can abduct.
For the period of a show jumping test or a dressage test, there's perhaps no point in using particularly invasive surgery to correct that, when you can get by with much more conservative methods. So it's important to constantly remember what that horse is to be used for. We we don't have to treat every horse as a, national hunt racehorse, or, or, or, or an inventor.
Is there anything else going on as well? That's incredibly important. And we've done some other studies with horses following laryngeal interventions for treatment of disease, and we found a lot of other conditions that can occur at the same time.
And as I will come back to many times in this, this talk today, it's Very rare to actually find just one condition going on at once. You'll often find multiple abnormalities, and some of those will only be seen when the horse is exercising. So resting endoscopic examination is perhaps not as useful as we would hope it would be for certainly plate problems and laryngeal problems.
The things that it is useful for are aytinoid chondritis, so you can see this left erytinoid cartilage here. This is the early stages of a horse with erytinoid chondritis, so. Excuse me, an infection, an inflammation of, potentially an infectious inflammation of the leftytinoid cartilage in this case.
You can see here, and you see a swelling of that, this can affect its function, can obviously occlude the airway to a degree, certainly be associated in many cases with respiratory noise, and that is a, absolute diagnosis at rest. Of course, this could be causing other problems when the horse is exercising, but you can Pretty much diagnose that and certainly treat the early stages of this condition with the horse based on the resting endoscopic examination. Eiglottal entrapment.
This is where the epiglottis becomes entrapped in a cloak of the sub-epiglottic tissues, the mixture of tissues beneath the epiglottis, potentially they are excessive tissues underneath there. We're not fully sure there's a few hypotheses as to why this occurs and why this is so variable. But certainly that's what we have, in this case here, and you can see the area that's ulcerated, the submucosal, sub epiglottal tissues here have become, ulcerated, and you can see that the actual normal defined, epiglottis, is not easy to see at all.
Well, you can't see it, should I say. Cleft palate, you can see why this horse was potentially presented, the amount of food, that is in the upper airway. These are classic diagnoses, in youngsters folds, normally with the milk coming down the, nostrils, .
And this is what a cleft palate looks like, so the soft palate has not formed correctly, leaving a permanent fistula between the oral and nasal cavities. And as I say, this is an ideal diagnosis at, at rest. So as I think you've gathered from the talks so far, exercising endoscopy is certainly something that we now advocate in the majority of forces subject presented for upper airway examination.
The original way that this was done, as I've already alluded to, is high-speed treadmill endoscopy, and certainly it is in some institutions still used, and I I certainly still feel personally that treadmill has a, has a role to play in some conditions and some horses. It was particularly useful, and we used it a lot in the early stages. A lot of those original studies came off the back of high-speed treadmill endoscopy.
Disadvantages, or the, not so much the disadvantage, but the factors to consider is that the horse does need to be trained before it goes on a treadmill. You can't just hop a horse onto the treadmill and expect it to gallop at 38 miles an hour, without any training, and some horses did resent it. Most of them were fine once you've given them a period of training, and they did accommodate to it as well.
You obviously needs specialist equipment, not everybody has a treadmill in the garage, and you do need a large team of dedicated. People, as you saw from that, the picture that I showed you there, it takes a lot of people to get this horse onto the, onto the treadmill, keep it on the treadmill and keep everybody, including the horse safe. And I think everybody that worked in treadmill, treadmill facilities, hated it, really.
They all seem to, hate doing the tread doing the treadmill examinations because of the safety factors, which is obviously to, to be considered. Most treadmills, in fact, pretty much all I've, I've seen, can incline, so you can put the horse on a gradient, potentially lowering the ultimate speed that the horse is working at, potentially allowing you to reduce the speed that the horse is working at, as I say, and reduce the potential for any musculoskeletal, injuries. However, it's an unnatural scenario for a horse.
Saying this, a lot of flat race horses are trained on treadmills as well, in addition to their normal routine at the moment. So there is a potential that it perhaps is more natural for some horses, but it's certainly, there's not many. Dressage horses and show jumpers and inventors that are trained on treadmills.
So it is a very unnatural scenario for them. It's a very unnatural surface. It's not what they're normally used to, and this all potentially has an implication on the diagnosis of what we are seeing.
Overground endoscopy, as the microchips and computer technology and battery technology developed throughout the last decades, it has allowed us, or allowed a couple of companies, to create some pretty useful overground endoscopy pieces of equipment. Here you can see a horse, the lead horse in, in, in this pit. He has an endoscope passed up its nostril, fastened to a specialised bridle, connecting down its neck to a computer system, both sides of the saddle, to record and send the images, to a monitor at the side.
And this has allowed us to use this more often. The horses don't need training. They're on a natural surface.
They are working, as they normally would, so you don't take them out of training. You keep them in their normal training protocol, and you can just put this scope on and add it into its normal day. You can work them, with each other.
You can use rider interventions, which is potentially more important in sports horses, dressage horses, show jumpers, using specific rider interventions to induce, the, laryngeal problems that we're potentially seeing. You can work them together. You can basically race the horses, and you can see in that picture I showed you before, just two horses together.
A lot of these conditions, especially soft palate problems, will only really be seen in horses racing, and that is a classic history, as in the horse trains beautifully, never makes a no. He's never pulls up, goes to a race track, pulls up near the end of the race. So ideally in training, you need to run this horse as long as it's is it's, racing for, and have a buddy for it to race against as well, which, of course, you can do with overground endoscopy, you can't really do that on a treadmill.
There's less reliance on staff. Some of the pieces of equipment allow you to do this solo. If not, you can use, one other person maximum really, and then the jockey is all you need to get the horse working, the horses tolerate it incredibly well.
I think out of many, many hundreds, if not way over 1000 examinations that I Been involved in both here and and previous places I've worked. I think we've had two horses refuse to do the overground endoscopy or certainly react badly to it. They all tolerate it after a few minutes of it being up the nose, as we know from other forms of endoscopy that we do, once the scope is actually passed up the nose, the horse tends to relax quite well.
So this is a horse, working up the gallops in Newmarket here, up the hill. It's in its normal string, as you can see them all coming up here. It's racing one of its buddies from the yards, normal jockey that it has, normal partner that it goes training with, and as I say, we can integrate this beautifully into its normal training regime.
As I've alluded to in the past, you can also use it with horses in the fog, as you can see here. You can use it during an arena, get the horse to do what it normally does, get the horse to work in the way that it normally works, so that we're not missing anything, in these cases. And as I say, if need be, youngsters or horses that for whatever reason, can't be ridden at any particular time, you can also lunge the horse, you can use a surfing around them, keeping the equipment on in situ.
You can work them at the lunge as well and get some good diagnoses as well. This is kind of what we're seeing, so this is a video. Excuse me, this is a video of a horse, .
There we go. Working as exercise here, this is typically what we see, so this is galloping, and you can see that it displaces its palates. And this is the kind of picture that we're getting from these exercising endoscopies.
There's plenty more pictures and videos that I'll show you as we go further on into the tour. Sound analysis, this was certainly something that has been around and people have been working on for a long, long time. As we know, horses make different noises with different conditions.
So there's certainly been a lot of work, and there's a lot of work still ongoing into sound analysis, trying to work out whether we can actually define specific noises. For specific conditions, and we can make accurate diagnosis with just putting a microphone on the horse's headphone. At the moment, we haven't been able to do that.
There's no conclusive findings from these studies at present. There's certainly some hints and tips, but there's nothing that at this moment in time is allowing us to implicate eliminate an endoscopic examination. Upper ultrasonography, this has received a lot of, and still does receive a lot of coverage at the moment, and it's certainly something that we use quite often.
There's some new techniques coming, becoming available with different probes. Certainly this is, using a conventional linear probe that we'd use for tendon scanning. We can scan the larynx on the lateral and the .
Potentially also the dorsal aspect as well. You can use the technique to use this to actually allow you to look over the dorsal aspect of the larynx, but certainly the initial work was done on the lateral aspect of the larynx and the ventral aspect of the larynx, and you can get some really nice pictures. So this is the right side of the larynx, and the muscle that we're focusing on, or certainly the early work was focusing on was the cricorretinoidus lateralis, the CAL muscle.
That is also innervated by the recurrent laryngeal nerve, and it is believed that this muscle, starts to atrophy before the CAD muscles. So there was a big hope, and there's certainly some people still utilising this, but there was certainly a big hope that this was going to give us an early indicator of recurrent laryngeal neuropathy and obviously very useful or the the potential usefulness of this in a sales scenario. So this picture here, just to take you through it, so this is obviously the skin at the top, we have got the thyroid cartilage here.
Below that we have the CAL muscle, and then this, and it has two bellies, you can almost make out the two bellies of the CAL muscle, and you can then see the erytinoid cartilage and just off the pitch, this sort of trumpet horn or ski slope or whatever you fancy calling it heads off towards the muscular process on the left of this picture here. So this is the CAL muscle. And this is the contralateral left CAL muscle in a horse with, with recurrent laryngeal neuropathy.
So the same picture, and the two pictures side by side, you can see a difference. And the difference that you are normally seeing in these muscles is that they become more dense. So, As more fibrous tissue is laid down, as the, as the muscle starts to atrophy, you can see that it becomes more hyper-ecogenic.
And this is the, the typical finding that we'll see in horses afflicted by recurrent laryngeal neuropathy. Mhm. It's also particularly useful and potentially transcutaneous ultrasonography.
And there is some work ongoing at the moment to show that it's usefulness and it's perhaps not as useful as we originally thought it was in predicting the current laryngeal neuropathy, but watch this space, that work is being undertaken at the moment at the Royal Veterinary College, in London. But certainly, it is particularly useful when there is a potential for a congenital abnormality. Now, this horse was a horse that was presented, shortly after a vetting.
It was considered that it had recurrent laryngeal neuropathy, . And was bought at a knockdown price in the thought that it would end up just having a tie back or something in the future or something else that will come to towards the end of the the lecture. But in actual fact, I thought it looked a bit strange, and when you palpated the larynx, it felt really, really strange.
And I think you can see on this picture here, this is the right side of the lary. This is the left side of the larynx, and it doesn't really have much of a thyroid cartilage that's pretty much missing. And this is very, very useful to give you an idea, and this is obviously this is something that most of us have in our practises are in the boots of our cars.
If you've got any abnormalities of larynx is putting on an ultrasound probe. And using the scanner that will tell you a lot of information and that horse there, as I say, had some form of congenital abnormality that I'm not going to label without knowing exactly what it was, but certainly the sort of 4th and 6th brachial arch defects are potentially one thing. However, whatever it is, it doesn't have a thyroid cartilage, which is not good for the future use of that horse.
Advanced diagnostic imaging has been used, in some cases, once again, in congenital abnormalities. This is a 4th brachial arch defect, in a postmortem larynx that we have. I wouldn't say we use this regularly, for diagnosis of problems.
I feel that we get enough information from the other things that we have available at this moment in time, but it is a possibility in some cases. So, looking at the conditions individually in more detail, I'm gonna start with soft palate dysfunction, because this is the one that causes us to scratch our heads more than anything else. It's, we've seen this video already.
This is basically what we see. We see the horse exercising away, doing OK. You can then Start to see the palate becoming unstable.
You can start to see these apoglottic folds starting to come in, and then you can see it suddenly, switch and suddenly displace. And the main problem that this causes to the horse is that it can't breathe out. So, it's working away, it can work, it can get air into its lungs, and then as soon as it tries to breathe out, that piece of soft palate comes up like a big parachute, a big sail, and it can't breathe out.
And the normal clinical sign that the horse will present with, in these cases is that it will stop. And this is a classic horse that pulls up, swallows its tongue, or does something of a similar nature, or certainly regard referred to it, as a similar thing. Political instability, is often, often, I don't say every time, but certainly often seen, proceeding, dorsal displacement of the soft palate, and certainly if you look at them frame by frame, literally a couple of strides before the displacement happens, you will see this.
So you can see here the epiglottis, is looking like it's making a bid for freedom below. The soft palate, you can see it just sort of curling around and this piece of the soft palate coming upwards. We also see this, we think, certainly, it's either because we're not exercising the horses as far as we need to or not putting them in a racing environment, but we certainly seem to see this as a standalone condition.
And we certainly have seen this often in A number of horses before and after particular procedures, so the dorsal displacement of the soft palate has has resolved, but the horse is then left with palla instability. And its significance with regards to both noise production and performance limitations is arguable at the moment, but certainly it is a finding that we often see on exercising endoscopic examination. Dorsal displacement of the soft palate, you've seen this picture before, is the, I, I rightly or wrongly refer to as the end stage of palatal dysfunction.
And it's basically, as you say, you can't see the epiglottis anymore, and you can imagine as that horse is breathing out, it, it can't do. That comes up fully, and, basically, it can't get the air out of its lungs. So the first thing it does say is stop.
Dorsal displacement of the soft palate has many treatments, which, as we know, in the equine veterinary world, probably means that there is no one treatment that is any good. And there are a number of treatments available, and there are a number of treatments that we use. One of which is tack modifications, so utilising, Cross nose bands, tongue ties, these are things that we can do with horses.
Obviously some disciplines don't allow certain, tack modifications, and their efficacy is, has been reported, actually. There is a paper show. Knowing that tongue toes are as effective as other surgical interventions for dorsal displacement of the soft palate.
I don't think anyone knows exactly how either of these things works. There's certainly some hypotheses, but certainly, they do seem to add some benefit, whether that's a rider thing or not, we don't know. Thermaquarter of the soft palate has been done for many years, once again, exactly how this works, if you think about it anatomically.
It's quite hard to see how this does work, but it certainly does seem to. There's a number of horses that undergo thermacoterry of the soft palates, on a regular basis, and this is literally what it says on the tin. This is a horse undergoing thermacoterry of the soft palate from the oral aspect, which is just basically burning the palate with hot irons.
It can also be done transcendoscopically from the nasopharyngeal side using a laser. The efficacy of, of this procedure from both techniques is variable, and, it certainly doesn't seem to be the be all and end all of dealing with soft palates. The laryngeal tie forward procedure is the surgical procedure that certainly in its original, presentation seem to offer the biggest hope.
And certainly in horses that it's diagnosed correctly in. And of course, I think we also have to bear in mind that there's perhaps a number of forms of, of palatal dysfunction in the horse. They may not all be the same, and that I won't go into too much detail.
It's out with the, out with the scope of this talk, but there's a number, if you look into this, a number of hypotheses as to what causes these, and there's the potential that there's 2 or 3 things, that cause, palatal dysfunction. The Thyrohyoideus muscle, and lack of activity of the thyrohyoous muscle is potentially one of them, and that's been shown to be one potential contributing factor, and certainly replicating that with a external prosthesis or an internal prosthesis, should I say. Has been shown to good effect, and that is the principle of the typhoid procedure whereby the thyrohyoideus muscle is replaced with a, prosthesis, and basically the larynx is tied forward, hence the name.
As I say, in the correctly diagnosed horse, and obviously with some degree of luck as to the fact, the reasoning why the horse is getting dorsal displacement, the soft palate, this works particularly well, and certainly that gives us our highest return of success in the horses that we do on our practise here. There's a number of other things that have to be taken into account once again, as I say, there seems to be many causes for this condition. Increasing the fitness of the horse is important.
There's no point in doing a tie forward on a horse that's only just come into training, or has only just started working. Because if it's not fit, it's palatal musculature is equally not that fit. And it's incredible sometimes when you just repeat the overgrounded scope six weeks later when the horse is in improved fitness, the pallet is absolutely solid as a rock and not displacing.
Lower and upper airway inflammation has also been implicated, in palatal dysfunction, potentially by lymphadenopathies, the, nerves controlling, the palatal musculature, pass. By a number of lymph nodes, and potentially they can, experience a neuropraxia for a period of time as a result of this inflammation, and certainly treating lower and upper airway inflammations have, resolved palatal dysfunction in a number of horses. As I say, we've had tack modifications, palatal thermacaery, and the laryngeal typhoid.
The future perhaps holds us some hope. We'll come back to this in a bit more detail, towards the end of the talk, because a lot of this work has been done with the recurrent laryngeal nerve at the moment. But obviously, in some cases where there is a neuropathy or potentially a more permanent muscular problem of the palates, the use of external pacemaker devices, I keep saying I mean internal pacemaker devices, potentially has a role to play in the future, but this is something that at the moment is a hypothesis.
It has been tried in a couple of horses, but at the moment, it's a long way off at this moment in time. Excuse me. Moving on to the next condition, that kind of goes hand in hand with political dysfunction, or potentially goes hand in hand with dysfunction is medial deviation of the epiglottic fold.
It's also referred to many text as our epiglottic fold collapse and axial deviation of the epiglottic folds, all of which are the same condition. And this is basically what we see here. So we're looking at a horse exercising here, and you can see, especially as we go into a slower motion, you can see.
These are epiglottic folds being pulled into the airway of the horse, and you can see that picture there, where it's freeze framed, that can cause two things. It causes a noise. The noise is generally a whistle, and we often see horses that can fail sales, vetting, with a whistle.
You then put an overground scope on them, look at them, and it's actually the epiglottic fos that seem to be causing the whistle, and the larynx is solid. They, they can cause a number of conditions, they can be related, sorry, number of clinical problems. You can see in this one here, you've got obstruction of the trachea, you've got performance issue going on in this case.
They can also be related to a number of things. It is believed this once again is something that is potentially being disproved at this moment in time, the fact that these are non-muscular, certainly we've there is some Research going on at the moment showing that there are muscle tissues within these structures. However, the important thing is they are very much dependent on the structures around them for their stability and their tautness.
So if the larynx is collapsing, as you can see in this side here, it loses its tension. And equally, if the palate is unstable, and is moving in a dorsal direction, they equally will lose their tension. So, hence why they are often seen.
In complex with, soft palate dysfunction and laryngeal dysfunction, and you often see them in these cases. And as I say, you can often see them in complex with many other things. They're related to a whistle, or they can be associated with a whistle, and they do cause some form of airway ollusion.
Treatment of them, if they don't resolve with normal palatal interventions, then you can remove them. And transcendoscopic laser resection of these is possible. So this is basically under sedation, local anaesthesia.
You grab holds, you've got a scope of one nostril, you've got a transcendoscopic, a transcendoscope, a, trans-nasal forceps up another one, up the other nostril, grab hold of it, and then laser it away under tension. And we've had some good results with this. This seems to work quite nicely and certainly is often used in complex with other procedures such as a laryngeal typhoid procedure.
Laryngeal dysfunction, is, as I say, incredibly important. You can get it in these milder cases here, whereby you're maintaining abduction of the larynx, but recurrent laryngeal neuropathy, as we've already said, can also affect the vocal folds, and you can get vocal fold collapse as a result of recurrent laryngeal neuropathy. And certainly in a young horse, that will give you an indicator that that's potentially one of the first stages of the problem, with, laryngeal.
Collapse coming in due course, as we can see in this case here. So this is a resting endoscopic examination of the horse, with full loss of its craytinoidus dorsalis muscle, CAD muscle, and an exercise you can see, as that horse breathes in, this part of the, the, the retina cartilage gets pulled right across to the right hand side there, pretty much in some cases, completely occluding the airway. What do you do in these horses?
Well, it's very much dependent, as I've said to you before, what is happening, to the horse, i.e., is it affecting its performance?
Is it making a noise? What is the horse used for? If this horse is not a high performance athlete, then potentially, perhaps not this case, but certainly one of the other cases that I showed you where it was just a vocal fold.
You can do a laser resection of the vocal fold. As I showed you in the previous picture, you do it exactly the same way, removing it. The ventricle as well, traditional hob day techniques.
So in addition to the vocal fold, you then put the forceps into the ventricle, pull, pull the ventricle out, and then cut that off as well. So this is what we commonly refer to as a laser hob day. So this is the hob day technique that has been around for many, many decades.
In some cases as well, and certainly once again in high performance animals, you might want to do laser resection, laser transection of the right vocal fold. The reason why you want to do a bilateral vocal fold, resection, especially with the laser, is the way that the tissues heal following thermal damage. There's an increased risk of, Seeker tricks or webbing forming a crossing, of course, that will then result in a worse problem than you started with.
So what you tend to do, you only remove one vocal fold, and then you work on the other side, just doing a transection of that potentially. All the other potential is that you come back and take that out, 4 weeks later, for example, 2 to 4 weeks later, to remove that on a second sitting. As I've said before, if you're getting significant abiotic fold, collapse.
Associated with la laryngeal problems, you may want to remove the epiglottic fold as well. This is done, as I mentioned before, as a standalone condition. We often do find as well, that we will get our epiglottic folds collapse, even if we're doing tie backs, on horses, as I'll come to shortly.
So you might want to remove these at the same time. Obviously, if this is a horse under pressure to get working, then you do tend to do all of these things at one, particular time. The tie back procedure is, has been the mainstay of the treatment of recurrent laryngeal neuropathy.
This is a post-operative picture of a horse that has undergone tieback, a tie-back procedure or laryngoplasty, and you can see here that the leftytinoid cartilage has been pulled up and away. The tie back procedure basically involves replacing the CAD muscle with two sutures. The majority of clinicians use 2 sutures.
There's the odd clinician that uses one suture to do this. But the, the majority of people use two sutures to hold this back in place. As I say, you will then do the left vocal fold at the same time as well.
And some clinicians will also, as I say, trans. Set this right vocal fold and remove the epiglottic folds at the same time. Once again, as I alluded to a few times, it very much depends upon the use of the horse.
This horse is a show jumper, and is the horse I showed you with pretty much the complete, complete, loss of abduction, that I showed you in a previous slide. So, it is hoped that this is all it will need at this moment in time. Tie back procedures traditionally done under general anaesthetic, and many clinicians still do it.
However, recent advances in in sedation, local anaesthesia, and our understanding of these techniques, we can now do this standing, and this certainly seems to be, our preferred method, in certain horses. Obviously, if we are dealing with a renowned lunatic of a horse. We will still use general anaesthesia, but that goes the same for any standing procedure that we do.
And certainly, we try and do, try and do, we certainly do do a lot of our procedures at our hospital, at our practise, standing, fracture repairs, so doing tie backs kind of followed on quite nicely. So, we've had some good, good experiences with doing them, doing them standing, and as I say, it's our preferred first option at this moment in time. The future and certainly all the present.
CAD really innovation has been around for many years, but the technique by which we do this now seems to have refined it to a point that it works consistently. We're in the early stages of doing this as a profession, but there are many hundreds of horses that have had their recurrent laryngeal nerve innovation. Replaced or more importantly, added to by a C1 or a C2 nerve graft.
This is a location of the nerve, the C1 and the C2 nerves, mainly the C1, being located using a nerve stimulator. Once the nerve is st is located, and then strip back all the tissues. This is a normal stand, normal tie back approach.
And basically just looking for the nerves rather than bypassing the nerves and going straight through. You can locate the nerves when you've got a nice bundle of the nerves, you can then pull the larynx, towards you, and then you can thread the nerves through the CAD muscle. And then hopefully, anywhere between 6 and 12 months later, you have reinnervation of that muscle, to a degree that the horse is able to use its ytinoid cartilage as Mother Nature intended, just using a slightly different nerve.
This is also, as I'm sure many of you listening have heard about the potential use of pacemakers in recurrent laryngeal neuropathy, and that is something that has been used in some horses and hopefully will become. A reality in most cases, the pacemaker actually works on the C1 nerve that we've then previously innovated this muscle with. So it's used as an adjunct, and the main advantage of the pacemaker is that it will bring down that re-innovation time from 6 to 11 months to under 6 months and hopefully shorter in some cases.
Therefore, increasing the potential for its use, certainly the Reliance on an entire racing season out in thoroughbred flat racehorses is a non-starter in all but the most exceptional of horses, and, so the pacemaker might bring it more in line with the traditional tie-back procedure. Epilottal entrapment, we've seen this picture before. You can treat this quite nicely, using a guarded hook knife that you pass up one of the nostrils, and guard it with a scope.
Many apologies. I did have a nice video of this, that seems to have been corrupted and a computer change, and it's the only time I've ever recorded a video of this procedure. You normally see tents doing this in case you hit the ethmoid terminates on your way out with the guarded knife, but this is basically what it results in afterwards.
And you, can release those quite nicely, quite successfully using this technique under sedation and local anaesthesia. Areytinoid chondritis, medical therapy, is your normal starting, starting, starting point for that. So, antibiotics, anti-inflammatories, rest for a period of time, from exertions, can help in the majority of cases.
If not, if the chondritis gets out of hand, you can remove that aytinoid cartilage using an aytinoidectomy technique. Which, is, provide you with variable results, and, it's not something that's done every day, but it's certainly something that we have to do once or twice a year in our population. Nasopharyngeal collapse, takes on a number of forms.
You can get these dorsal collapses of the nasopharynx, you can get these lateral collapses of the nasopharynx, and circumferential nasopharyngeal collapse. Once again, this is an aetiology. It seems to be related to palatal dysfunction, obviously in the circumferential ones, it is related to palatal dysfunction.
And in the past, it was bad news. Well, it was pretty much bad news, and relied on the use of a tracheostomy, pretty much for these horses to be able to cope. Obviously it's now very bad news in the fact that we can't use a tracheostomy, in most competition horses, and pretty much all competition horses now.
So it, it, we're faced with a problem in treating these nasopharyngeal collapses. Neurological involvement in the condition has been shown, and certainly, the team at the University of Nottingham have used gabapentin and managed to get some of these horses, resolved as a result of using gabapentin. And they seem to be having some good, good results in some cases.
There's also a technique that is modified from the treatment of tympani in falls and problems in fals whereby you can enestrate one guttural pouch to the other. And the theory here is that the guttural pouch, don't empty of the air well enough, causing an expand expansion. Of the guttural pouches causing the problem, the nasopharyngeal collapse and transcendoscopically, you can enestrate one side to the other, which you can do quite readily, in the sedated locally anaesthetized horses, allowing an equilibration of the pressures from one guttural pouch to the other.
The only useful adjunct to that is resecting the salpingopharyngeal fold at the entrance to the guttural pouches. Once again, you can do this quite conveniently, transcendoscopic laser, and a loop as well. You use a transcendoscopic electrothermaco tree.
Loop at the end to take the last little bit of it so that you don't damage the, the oste to the guttural pouches. But these are techniques that we've done a handful of. Some have worked very well, and others haven't worked as well as we'd like to.
We're in the early stages of doing these as a profession, and as I say, we've had some good success in some cases. So, quickly, whirlwind tour of upper diagnostics and therapeutics, the whirlwind end to other things. Epilottic retroversion, remains somewhat problematic in many cases.
There has been a laryngeal tie-down procedure mentioned. I have no experience of that myself, and I know people that have done that have had some success, and, and no success. Cricotracheal ligament.
Collapse, we can see this here, so you can see this ligament collapsing underneath. There is a method by which you can imbricate that, reducing that, that was described by the Glasgow group recently, and certainly I've had a couple of these cases that we've managed to resolve using that technique. Ventromedial luxation of the apex of the retinoid cartilages has many names.
Refer to it as VAC or VMA or CAA. There's various things. However, a condition with various names doesn't have various treatments, and the treatment of it is not really been been described yet, and this is.
Basically what we're seeing here where one of the erytinoid cartridges, it can be a precursor to recurrent laryngeal neuropathy, and you will see VA in early stages of recurrent laryngeal neuropathy, examine them 34 months later and you'll have full, erytinoid collapse, but it can also be a standalone condition as well. As I have mentioned many times, you will get multiple diagnosis in many cases. This has got VAC, it's got a retinoid collapse, are epiglottic fo collapse, vocal fold collapse, pola instability.
Where do you start? Good question. But we do see that, quite frequently, unfortunately.
So that's the end of the whistle stop tour. I'd like to thank, a lot of my colleagues and friends, Paddy Dixon, Sophia Barracka, Louis Smith, Fabrice Rossignon and Justin Perkins, and I'll take any questions that you may have. Brilliant, thanks very much, Tim.
Really interesting talk, and really enjoyed quite a lot of those endoscopy videos. So we have one question, regarding if you could just re-clarify the muscles of the, the larynx again, I think it was around the time when you were showing the ultrasound image. I don't know if how easy to look back into your.
Yeah, sure, so the muscles of the larynx, the, the two main muscles, the main muscle of the larynx that we're dealing with is the cricorytioidus dorsalis muscle, the CID muscle, and that's the muscle that. Controls the abduction of the erytinoid cartilage, and if that muscle fails, as a result of a reduction in its innovation by the recurrent laryngeal nerve, and that causes the problem. So basically, that muscle will atrophy, it will fail, and the airway will collapse.
And That's the main muscle that we're dealing with. It's partner, the CAL muscle, the cricoytinoidus lateralis, is also innervated by the recurrent laryngeal nerve, and that acts to add up the erytioid cartilage, so pull it internally, so it works in the opposite way. And it is believed that that muscle loses or starts to atrophy before, the CA CAD muscle.
And that's the muscle that you can, that you can ultrasound scan very easily using an external percutaneous ultrasound technique. And they're the two main muscles that I mentioned in the talk. Brilliant, thank you.
And then just one quick question before we run out of time. So horses working on the bit, are, is that somehow affecting their airways, or does it not really matter if it's just. Yeah, a lot of people do think that it does, and certainly the way in which a horse can it is working, potentially has a problem, hence the reason why things like cross nose bands, spoon bits, and tongue ties potentially work.
So it potentially has. The theory is that it potentially causes a differential pressure between the mouth and the upper airway and certainly may be related to pola dysfunction. As to how we'll ever prove that, I don't know.
But obviously those are the kind of horses that may respond very nicely to a to a cross nose band. And if you can. Resolve your palatal dysfunction with a cross noseband instead of 2.5 grammes of airway surgery.
It's a lot more convenient and better for everyone, so yeah, yeah, exactly. Brilliant. Well, I'm afraid that's all we've got time for, so, thank you very much, again, Tim.