Video of Tendon and Ligament injuries in the non-athletic horse

Good afternoon. Yes, so we're gonna spend the next hour discussing a number of soft tissue injuries sustained by horses, and as the title suggests. The focus of this talk is going to be those injuries sustained by by all equines essentially, with a focus on those more common in older animals.

So we're really going to leave behind the acute injuries of racehorses and competition animals, the superficial flexor tendon injuries, the suspensory injuries, and look at the more general horse population and the problems that they can find themselves in. So we'll be covering a few conditions today and I think one of the themes really that I hope you'll take home from this is that a majority of these conditions can be diagnosed and identified and managed really. In a majority of cases with good clinical examination skills and ultrasonography, and often don't require any more than that.

So very easy to to do a very good job wherever you are and whatever tools you have available. So the injuries that we're going to fly through this afternoon are listed here. First we'll look at injuries of the digital flexor tendencies.

It's a big topic, a lot involved there. We'll have a brief look at superficial digital flexor tendinopathy in the older animal, rather than our racehorse counterparts. We'll look at checked ligament desmitis, so accessory ligament of the digital flexor tendon injuries.

Fluxations of the superficial digital flexor tendon of the calcaneus, of the hock, rupture of the peroneus tertius, and degeneration of the suspensory apparatus, another, condition of older animals. So we'll start with the digital flex attendant. Now this will be a region that I'm sure all of you who treat horses will have seen lameness of this region many times.

It spans a number of different pathologies and injuries, but it's certainly a common finding in the general horse population. A brief look, this is the structure that we will, look at each of these conditions in, so this will be our template for looking at each of the areas of injury for this afternoon. So a brief thing about the anatomy of the tendencies, which is vitally important, particularly given that ultrasound evaluation is such an important part in looking at this condition.

External anatomy. We can see here, a limb photograph with, a fusion of the digital flexitten sheath. It runs from, a proximal out pouch, just sitting above the level of the fatlock joints, and it extends down the palmer aspect of the limb, to between the heel bulbs on the Palmer aspect of the past.

You can see some effusion here on the Palmer aspect of the pattern. And again, approximately, it's difficult to appreciate or you can't appreciate a fusion over the, directly over the Palmer aspect of the fat lock joint. And that's due to the fact that the, tendon sheath is constrained by the Palmer digital annular ligament, which runs from sesamoid bone to sesamoid bone across the back of the pet lock.

This is a cadaver specimen. It's not too easy to see, but I hope you can appreciate the the foot here distally, the cannon bone, going approximately at the top of the image, and the tendons have been reflected distally from the the digital sheath, to show us the palmar sputum at the back of the fat lock, the dorsal aspect of the tender sheath, and you can see the transected ends of the annular ligament at this level. Running through the tendon sheath is the deep digital flexor tendon.

And the superficial digital flexor tendon, so we can see the the deep reflected here, just highlighting another important structure related to injury inside the sheath, and that being the manica flexoria, which is a soft tissue connective band or collar, I suppose. That wraps around the deep flexor tendon, runs from the margin of the superficial around dorsally, around the, the DDF and attaches again on the other margin of the SDF distally, it has this very thin. Distal border, and then extends approximately to join the the sheath wall essentially.

So those are some important features of anatomy. There are other soft tissue, connect connective, meena attachments and other bits, but those are our most, relevant structures. Presentation of digital flex attendant lameness, well, yes, the horses will be lame, signalment wise, this condition can occur in all types of horses.

More athletic animals may be prone to certain types of injury within the sheath, and we certainly see overrepresented in our horse population here at Lip Hook, the cob and pony type breeds that often have effusions of the digital sheath, particularly affecting the hind limbs, perhaps related to an ligament constriction and often injuries within the sheath concurrently. So certainly older type pony breeds are commonly presenting with, with this condition. But essentially any type of animal will present with lameness, can be forelimb or hind limb.

There will be a fusion of the digital flexorendon sheath, often asymmetric, more marked in the affected limb, but often present in the contralateral limb as well. There may be heat associated with that effusion, and more than likely there'll be pain on flexion of the distal limb and a positive response to a distal limb flexion test. And if you pick up the limb and carefully palpate the tendon sheath, often you'll feel thickening through the sheath, abnormal soft tissue, on palpation.

Often just above annular ligament level, and there may be pain on palpation vocally as well. So do take the time to have a careful palpate of these tendencies. It can often give you a clue that this isn't just a an iatrogenic non-significant effusion, that there may be something more severe going on in there.

Now, there's all sorts of injuries that can be occurring inside the digital flexitten sheath that cause lameness and. This may be possible to identify what they are on ultrasound or ultimately at oscopic surgery. These are the some details pulled out of two fairly recent, retrospective studies that evaluated the findings of horses undergoing tenoscopy of the digital flexor tendon sheath for non-septic tumour synovitis.

So there's over 200 cases here, and all had pathology identified within the tendon sheath. The most common lesion being tears of the deep digital flexor tendon. And most common in both studies.

These tears were prima primarily identified within the forelimbs. And these are usually comprised of longitudinal linear splits and tears in the tendon. There's often frayed, recoiled fibres, sometimes granuloma formation of those recoiled fibres, that are identified at surgery.

Tears of the manica flexoria also comprise a reasonable number of cases in these two studies, along with tears of the superficial digital flexor tendon or tears of the tendon sheath wall itself. Manica flexoria tears are more commonly identified in the hind limbs and certainly more commonly for me, seen in those common pony type breeds, so, certainly the Arensburg paper were athletic sort of sport horses primarily, and I suspect that's the reason why they saw a predominance of deep flexor tears compared to Maica flexoria tears. Interestingly, none of these horses were identified to have annular ligament desmitis or constriction through the fetlock annular canal as their primary lesion.

So a number will have had their annular ligament transected to increase the space through the fetlock canal. But they were not considered to have that as their primary pathology. Which is interesting, I suppose in flagging up that although this might be identified on ultrasound or suspected on clinical exam, there is often or invariably something else going on inside this 10 sheath.

So diagnosis of these lesions. Primarily, you'll have a strong suspicion of a digital flexor tendon sheaths lameness on the basis of your clinical examination. Diagnostic analgesia is also very valuable.

I'll often perform or, or, or pretty much always perform diagnostic analgesia, particularly if I'm considering, tenoscopy in these cases. I'll usually place a digital nerve block in the first instance to rule the foot out of the equation, and then I'll perform intrathecal analgesia of the digital flexi. My preferred approach is to, aseptically, clip and aseptically prepare the Palmer aspect of the pastan and then pick up the limb and.

Make my approach at the Palmer Pasan level. So long as the confirmation of the horse makes it possible to do this in an aseptic way. Some of the very sort of big heel bulb called short Pasan horses, it's a little bit tricky.

But that's usually a very nice approach, to perform my diagnostic analgesia. It's worth noting, however, that not all horses block completely to analgesia of the tendon sheath. Presumably because, diffusion of local, if there's a very constricted annual ligament, might be limited.

But certainly, I'll, I'll sometimes, not be surprised to see only partial response to diagnostic analgesia. And if my suspicion is still very strong that this is the area, I might go on to, place a perineural nerve block of the palmar nerves. Just above tendon sheath level.

So the, the back two portions of a low 4 point or low 6 points, injecting 2 mLs of my local anaesthetic, between, just under the skin, between the suspensory ligament and the flexor tendons. And that I would expect to abolish my lameness, convincing. As I mentioned before, ultrasound examination is a very important part of assessing these tendencies.

I'll just direct you, this is a very nice article published in Eine Veterinary Education a few years ago, which has some beautiful images of the structures within the tenant sheath. And it describes very nicely the technique of performing that ultrasound examination. It is very useful, but it can be very frustrating, you know cob type friends that have very thick skin, bristly hair coat.

they can be virtually impossible to get, . Diagnostic quality images from them, and all I can do is encourage you to take as best care you can to, prepare the limb optimally, so very carefully clipping the hair as short as you can in that region, . And soaking the limb for a long period of time in your ultrasound, contact gel.

Sometimes overnight, in some cases, you can place some gel, wrap the leg and cling film in a stable bandage, and plan to image them the next day. This can really help, but isn't always, enough in, in some of these thick skinned breeds. So just looking at a couple of features of of imaging, I haven't mentioned an additional method of performing diagnostic imaging in these horses, published very nicely in EDJ by this Jacksonel a few years ago now.

This is a lateral radiograph, a contrast tinogram of the digital flex of energy, so we have positive contrast that's been injected into the tenner sheath. Which just demonstrates to show us here the, the limits of the tenner she right down into the. Dalton and up into the dorsal recess here and delineating and highlighting the tendons for us nicely.

There's some details in that paper, really using this as a method to help identify tears of the manica flexoria. Details can be found in that paper. A few things to mention just about ultrasonography of the digital flex of 10 sheath.

Here on the right of of this slide, we have a transverse ultrasound image and a longitudinal ultrasound image taken at the level of this red line of the radiograph. I'm sure you're familiar with the anatomy of this level. But we can see here the Palmer border of the proximal sesamoid bones, deep digital flexor tendon sitting within the groove of that, and our elongated superficial digital flexor tendon sitting at the top.

Overlying this is our Palmer digital, Palmer annular ligament and soft tissue and skin overlying that. It can be difficult to isolate, the annular ligaments out of the soft tissue structures, which we'll come on to, shortly. But perhaps more useful is this longitudinal image, proximal is to the right of the image, distal is to the left.

So we can see this is imaged on the Palmer midline, the sagittal ridge of the flatlock is sitting deeply in here. Our deep digital flexor, superficial digital flexor, and you can see, the annular ligament coming in here as you . Look distally down the limb, it starts to comprise some of this soft tissue, thickening going over the back of the, fat lock joints, and you can really see the, the difference in thickness of the palmer soft tissues, to include the annular ligament.

Deep to the tendons, there's a beautiful image here of the manica flexoria. So this is the soft tissue structure that sits between these parallel bright lines, and it can be seen to taper off to a very neat defined point distally. It corresponds to the border of the manicau which we could see on that cadaver specimen.

And just highlights in this image how the distal border of the manica flexoria sits under the annular ligaments, and it's easy to imagine a hypothesis that thickening and constriction of the annular ligament over time might predispose to tears of the manica flexoria as these structures move approximately and distally over the back of the fat lock in and out of the constricted annular ligament. It's just a theory, but it certainly makes sense. Looking at measurements of the Palmer annual ligament, it's something that we all like to do, and I guess it's nice to see what the numbers are and provide some image or some numbers for comparison over time potentially.

So I said it can be difficult sometimes to isolate the annular ligament. Some people do prefer to simply measure the distance between the Palmer border of the SDF and the skin. Just take everything into account and use that as your as your measurement for monitoring of that individual over time or comparison between limbs.

But a nice way of picking out the annual ligament is simply just to move your ultrasound scanner off to the lateral and medial margin of the tendon and the image the . Annular ligament as it runs across the side of the ligaments and attaches onto the sesamoid bone. And then it's usually possible to either measure it in this location or at least to follow it and see where where it sits a little bit more easily.

There's no hard and fast published description of how thick an annual ligament should be. Usually a normal annual ligament will be somewhere in the region of 0.8 millimetres.

Some, writings report that normal is anything less than 2 millimetres, to me, I think 2 millimetre annual ligament would be considered on the, on the thick side. So we've identified our tendon sheath lameness, and we might well have a good idea about the pathology that's going on inside that tendon sheath. The ultrasound can be very useful and, and with practise, pretty accurate, I think, at, identifying the pathology going on in there, but it is absolutely not foolproof and if you've got one of these cob animals, it's, it can be useless.

So, I think if you do find a a a lesion or if you have a strong suspicion of a lesion within the tendency, scopy is certainly indicated to allow further evaluation and treatment of that lesion. Depends on the scenario and, all sorts of factors, but, certainly some cases of teno synovitis can be managed successfully conservatively, if there are no soft tissue, specific soft tissue lesions within that tendon sheath. So conservative management consists of medication with triamcinolone, possibly hyaluronic acid, and rest and controlled walking exercise, and some horses can do fine with this, although I always would recommend advising owners that if there are other lesions such as a deep flexor or manica tear, almost certainly when these horses return to work, the lameness will recur.

Of those horses taken into surgery, with a definitive diagnosis, it's quite a varied outcome of these cases. Those horses identified with the tear of the deep digital flexor tendon don't do that well, unfortunately. Arensburg paper found 38% of those horses returned to work, because unfortunately, we have no effective way of suturing or or closing these tendon tears currently oscopically.

And, sadly they do not heal well within the synovial environment of the tendon sheath. Manica flexoria tears in con in contrast, make great surgical candidates because the manica flexoria can be removed surgically, tuoscopically, and, of those cases, Finley Atel reported a nice number of cases. Of which 79% returned to full work following Maica fluxoria resection, and tuoscopic surgery.

One thing just to mention before we move on to the next, condition is that of a closed sepsis of the digital flexor tendon sheath. Occasionally, horses will sustain a puncture wound in the palm of Paan or or into the tendon sheath at another location, and although they have no wound, or have marked fusion, severe lameness and pain of the tendon sheath due to synovial sepsis. So just a little reminder not to rule that out as a possibility, just because you don't see a wound on the limb.

It may be worth clipping up very carefully evaluating the limb and if you have clinical suspicion, performing synoviacentesis, because. It certainly is, is a possibility with a a puncture wound, Blackthorn, so, and that's not something that you want to miss. So moving on, there's a bit of a fly through tendencies, let's move on to briefly chat about superficial digital flexor tendinopathy of the geriatric animal.

So we're not looking at a horse that's pulled up from from eventing or from racing. These are all the horses that by and large will be brought in from the field with acute severe lameness and a huge, bow on the Palmer aspect of their, metacarpus. So this is unrelated to fast work and certainly, in the late late teens, twenties, that sort of an animal.

The presentation will be very, . Very obvious diagnosis diagnosis will be very obvious, they'll have a, a huge Palmer bow, Palmer swelling, that'll be marked lameness. Heat and pain on palpation, and they will be sore, but if you pick up the leg and carefully gently palpate through the tendon, you might feel changes in the integrity of the tendon or the the structure of the tendon.

And these are chronic degenerative tendons that have had some further insults and have essentially disintegrating, really, you know, it's not a good place to be for these horses. Injuries are often proximal metacarpus level and may extend up into the carpal sheath. You may also see carpal sheath effusion in these cases.

So diagnosis is straightforward, treatment is really along the lines of any SDF tendinopathy, in the first instance. Anti-inflammatory treatment is, is the first port of call, so non-steroidals. I may give a single dose of, intravenous dexx if I'm not concerned about laminitic risks in these older horses, cold and support.

And I'm a huge fan of, of very applying a very good supportive bandage to these cases. You know, we're very decent 434 layer, good compressive bandage if not a Robert Jones, . The downside means you can't use cold therapy because once that bandage is on, it's not coming off too frequently.

But I think losing that ability is more than outweighed by the, the increased comfort that you achieve from supporting this limb and hopefully reducing propagation of the injury, if at all possible. So these horses, I, I get into a box. I get well, analges.

I put on a very good supportive bandage and let them rest up for a few days. I usually come back 4 or 5 days later and remove the bandage and often they are much more comfortable at this stage, although still lame, and then that may be a good time to assess the limb, with the ultrasound. I do try an ultrasound these, they're, they're quite interesting to scan because there is a very, very significant lesion, usually as marked as theF disruption, often spanning a reasonable length of the leg, do clip up into the carpal sheath region because you want to be able to follow follow proximately to the limit of the injury.

And I always scan both legs, as a matter of course, you may see changes in the contralateral limb, of course, as well. So these horses do do need time and they do need rest and they need to they need to be managed like any tendon injury, essentially, usually because of the degenerative changes in the ligament, they have a guarded prognosis for returning to any level of riding work. Usually we're looking to achieve pasture soundness or perhaps light hacking in these animals.

Sometimes it's a problem to, to keep them on box rest. These older horses that are perhaps retired anyway or semi-retired, they may have additional issues. Hock away for example, that makes it not easy to manage them in a stable.

There isn't always the option to manage them as you'd like to, but they really do need to be confined and a given time and and walking. But I think it is fair to say that many do re-injure, some do re-injure when they return to turn out, and often you see that even further proximal to the original injury. Not, not a particularly great outlook to see in these cases, but with diligent management, they can certainly settle down.

So let's move on now to our next soft tissue condition, and that's of desmitis of the accessory ligaments of the deep digital flexor tendon. Otherwise known as the chuckling ones. Quick recap first, again of a bit more anatomy, that is the checked ligament itself.

The check ligament is a continuation of the palmar carpal ligament that comes from the palmar aspect of the third carpal bone, back of the carpus, and then runs distally down the limb, dorsal to the deep flexor tendon, and palmer to the suspensory ligament. To the level of the mid cannon where it wraps around and merges into the deep digital flexitendum, as you can see, I hope in these nice cadaver images. It's a large structure.

It has the same diameter as a deep digital flexor tendon. And so it's very easy to to image and to identify as a, as in a a a a site of injury. Its function is to passively carry load and share some of the load of the deep digital flexor tendon.

At maximal extension of the coffin and fetlock joints, it carries passively, some of the load of the limb during locomotion, which prevents overstretching of the deep digital flexor tendon. What we do know is that degenerative ageing changes occur in the checked ligament. And so, forced to failure is lower in older horses as compared to younger ones.

So it very much is a condition seen more commonly in the more mature older animal. In the hind limb, the checked ligament is present in the majority of horses, but it's very small and may even be absent. Pathology in the hind limb is rare and if seen is usually more severe actually related to adhesions between the ligaments and surrounding soft tissue structures may be associated with flexual deformity and inability of the horse to place the heel to the ground.

So these cases present, as I've met for reasons I've just mentioned, in more mature animals, it would be very rare to see check ligament is mis in animals under 10 years old, and usually more often into the teens. The horse will present lame, usually unilaterally lame. And, it's often a, a typical swelling, at the location you would suspect.

On the medial and lateral aspect of the limb, at the, level of, the checked ligament in the proximal third of the metacarpus. There may be heat and pain and palpation of this region. You don't usually see much in the way of a palmer bow to the limbs, more of a lateral swelling.

So, so pretty much walking onto a yard, if you see, you know, if this is your lame leg that you're being asked to look at and you see a swelling in this region, you can be pretty sure that you're, you'll probably know what you're going to be diagnosing. Lameness is usually sudden in onset associated with, occurrence of the injury. So diagnosis, as in many of these conditions is on clinical exam, palpation but also ultrasound examination is useful.

A few things to note on ultrasound exam of the checked ligaments, as I said, it's a similar size to the deep flexor tendon. It runs in a very slightly different orientation to the deep flexor and superficial flexor. So if you're imaging specifically the checked ligament, you're getting that, on incidence as the brightest structure at this level of the limb, surrounding soft tissue structures will usually be a little less eogenic.

Because you're not quite on incident to those when you're on incidents to the check ligament. The, it's important to assess the margins of checked ligament. They should be neat and well defined and often with pathology, well, the whole ligament's enlarged, .

And tends to sort of wrap around the deep flexor, and have less distinct neat margins to it. So scan around both sides of it. The structure of the ligaments will have a reduced ecogenicity with pathology.

There may be anechoic regions through the ligaments, but there's not usually a, a distinct corage ligament like you might see in a SDF in a, in a racehorse, for example. It's also a good idea to, to see if you can assess for the presence of adhesions, particularly in cases that may have been going on for a while. So this requires you to pick up the limb and try and get an image.

Maybe if you have somebody who might be able to help you, if you're able to flex and extend the the fat lock, you should be able to image the tendons moving independently, sliding across each other. If you can't, then that might suggest adhesion formation, which is important to know about because it will affect outcome in these cases. And adhesions can occur between the checked ligament and the deep flex, as you might imagine, but also between the checked ligament.

And superficial disal flexor tendon as well, at the margins of the, of the of the ligament. And as always, do compare with the other limb. We'll help give you information about relative sizes, .

And the condition of the other, other leg. So treatment again, conservative management in these cases, there's very little in the literature about checked ligament injuries, published outcomes, really there's just a small case study by Sue Dyson, that found that 10 out of 13. Horses managed conservatively with forum desmitis, we're back to full work at 6 to 9 months post-injury.

So really recommended conservative treatment to start with 3 months of box rest and controlled walking with a view to slowly increasing exercise levels if if things are going well. Obviously in the acute stages on steroidal therapy, . Cold hosing, anti-inflammatory based treatments to start with.

And it's important to maintain good foot balance. Often these horses grow, heal, and, they need to be kept with good foot balance, and stop them sort of raising their heels, as this won't, help the function of the limb in any way. Repeat ultrasound exam is useful.

You should see over time the epigenicity of the ligament return and it may not quite return to normal, but you should certainly see improvement in the appearance on ultrasound. And we do know that horses have a reduced prognosis. Well, obviously if they recur, you know, things aren't going so well.

Horses that are identified to have concurrent superficial digital flexor tendon injury, have a reduced prognosis, and, and horses that are exercised on the injury, as you'd imagine, don't heal so well and may end up persistently lame. Adhesions also reduce the prognosis and can ultimately result in fle or deformity of the limb. And that's where walking, controlled walking exercise is a really important part of the treatment process to try and prevent those adhesions from occurring.

But by and large not too common, and, you know, the majority of limbs for limb check ligament injuries, with a bit of, rest and walking to do very nicely. It does seem to be a trend though that, yeah, you can get one fixed and then the next year they'll do the opposite limb and you'll have to go through the process all over again. Unfortunately.

So let's move on now to have a look at some conditions of the hind limb. Have a little bit more anatomy to, to discuss, to look at these quite interesting conditions, I think, to see out on the road. They really do have some quite The next couple of conditions, so we do have some quite specific gait deficits, which are very easy to diagnose on on clinical examination alone, so very useful and to be able to recognise these and pick them up.

So the next thing we will look at is laxation of the superficial digital flexor tendon from the calcaneus, or the point of the hock or tuber calculate. The anatomy in this region, I'm sorry, this isn't a great picture, I've got a slightly better one coming up, but you may be able to see in this left hock, there is luxation of the SDF tendon. It sits to the lateral side of the point of the hock, certainly this whole area is a lot thicker than the skinnier, right hock in this case.

Anatomy, the sort of distal cross proximal to the hock, the SDF tendon, runs, sort of wraps medially around the gastricnemia tendon to become the most caudal soft tissue structure on the, on the caudal aspect of the, the distal cross. And it runs then distally down the caudal or plantar aspect of the limb to insert a pastin level. And as this tendon runs over the point of the hock over the calcaneus, it widens and changes in its structure to form a cartilaginous cap which sits over the bone of the calcaneus.

This, cartilaginous cap, I should have a picture, is attached to the calcaneus. Medially and laterally by a thick retinacular band, this, cadaver specimen is a. Such a transverse section of cut through, of the hock.

You can see the calcaneus here. This is the planter aspect of the limb, and this is the SDF tendon, or fibrocartilaginous, about to become fibrocartilaginous sitting over the point of the hock, and you can see there is a medial band wrapping and attaching onto the calcaneus and a lateral band doing the same, attaching onto the calcaneus. And luxation occurs, the most common cause of luxation is due to tearing of this medial retinacular band off the calcaneus, which means the medial side of the SDF is no longer attached, allowing the SDF to luxate laterally onto the lateral aspect of the tarsus.

These two ultrasound images show, the ultrasound findings of such a case, so in a normal. This is just proximal to the hock, the transverse section, the gastronemius tendon and the SDF sitting over the top of it. They're nicely lined up, on top of each other, with displacement.

This SDF can be seen sitting to one side of the gastric anus tendon, with irregularity surrounding it, showing displacement on ultrasound examination. So presentation, there's no real signalment predilection of this condition. It can happen in any animal, any type, breed, age, size.

There may be, it may be more likely to occur in horses with a straight hop confirmation. it's not been fully established. I, I don't think.

So, really a, a traumatic sudden onset, condition that can happen in any type of animal. Initially there will be severe lameness, and I think it's very disconcerting for the horse to suddenly have a change in the way their hock works, particularly if the luxation is an unstable or partial luxation whereby the superficial flexor tendon is able to move on and off the point of the hock, depending on whether the limb is flexed or extended. I think this can be very disconcerting for the horse.

They may be stressed, they may repeatedly kick out of the limb. So it can be quite dramatic initially. Things settle as the horse becomes used to it, or perhaps if the tendon becomes permanently positioned, usually naturally, things can settle down.

And diagnosis again is certainly achievable on on a good clinical examination. This is a much better picture that shows a permanent luxation of the SDF of the point of the hock. You can see it just sitting completely in the lateral position, not on the point of the hock.

And this is, yeah, a permanent luxation. The hooks extended, but the, the tendons still sitting out of position. Evaluating these animals, you may see this, and you know that that's your, that's your problem, if that's, a recent, occurrence in the horse.

Although if subluxation is occurring or unstable luxation, the SDF might be in a normal position at rest and will only move off the hook into an abnormal location when the leg is flexed. So you might not see anything particularly at rest, but if you observe the horse walking, stand behind the animal, observe it walking, and focus on the hock, you will see the the tendon flicking on and off as the horse walks, and this might be, . Quite resented by by the animal.

If you're able to trot the horse, you will see it as as a lame lameness on that limb, which will be reasonably severe in the initial stages. Sometimes you can, in a good, well behaved horse, you can actually put your hand on the hook as you walk them and really feel it flicking on and off. You might also appreciate local swelling in that area, more chronic cases can have peri tenderness thickening in the region, and calcaneal bursa effusion as well.

Ultrasound examination, I guess it's not imperative. I think you have your diagnosis on your clinical examination, but it might be useful or interesting to allow you to evaluate the SDFT, allow you to evaluate the retinacular attachments and see whether there's complete rupture or. A rupture or occasionally these, don't occur due to retinacular tearing.

You can actually get injuries to the fibrocartilageous cap itself and holes in those, and that should be identifiable on ultrasound as well. Treatment of this condition. Well, initially these horses will certainly benefit from some analgesia if they're very distressed and potentially some sedation as well, but they should usually relatively quickly settle and will be left with a degree of lameness.

If the luxation is permanent or becomes permanent and the tendon is sitting in a permanent, usually lateral location due to a medial tear of the retinaculum, then surgical treatment isn't warranted. It's very difficult to successfully reattach the SDF over the top of the hock. So, conservative management's recommended and they'll stabilise and get used to having a tendon in that location and, and be able to return to, to work.

So we'll discuss in a moment. If the luxation is intermittent and unstable, with the ligament continuing to move on and off the point of the hock, then that's an irritating kind of scenario to be in irritating to the tissues and will cause ongoing discomfort for the horse. The, there's a couple of options, but the most sort of.

Reasonable option, I think for treating this condition is, to perform. Tenoscopy of the carpal sheath with the aim being to complete the transection of the retinacular tear to create a permanent luxation of the SDFT tendon so that it sits permanently lateral and can settle down in the manner of these conservatively treated permanent luxations. And this is a nice keyhole surgery image taken from a paper by Wright and Mitchell.

Which, is showing us looking approximately up the carpal sheath, of a horse, so the calcaneus is here and the gastrocnemius tendon is extending approximately away from us. The fibrocartilaginous cap of the STFT is is here and the tendon again extending away from us, and the retinacular attachment has been completely transacted. It's all been tidied up, debrided, cleaned up, and the SDF is permanently moved to the side now.

Away from the calcaneus, and this is just an example of the amount of soft tissue that comes out of these, calcineal bursa following these resection procedures. There's a lot of thick and angry soft tissue in there and a fair amount of tidying up to do. Reattaching or suturing the fibrocartilage to reposition the SDF in its correct location has been reported in small numbers of cases, but there's significant difficulty with achieving that, and immobilising casting hot post-surgery, and, keeping things where they should be, after that sort of repair, a screw repair is, a little bit challenging.

So outcome of these cases. And there's one nice review of 19 horses that were operated in the manner I've just described to create permanent lateral relaxation of the SDF for treatment of unstable laxations. 15 of 19 of these operated cases returned to full work.

Although two later luxated the contralateral hind limb. And really the outcome you'd imagine to be similar to to horses that are treated, conservatively, they essentially ended up with the same condition. And we expect a good prognosis, although these horses do have residual mechanical lameness, you know, the SDF is not sitting where it should be, and they do have a slightly odd gait as a result.

And so this certainly limits some uses, some of these 15 out of 19 horses were used for pure dressage, for example, and that might be difficult to achieve, in in this condition, but there's plenty of horses out there that are jumping and doing other things, although I would say that. The fact that there is a residual gate deficit is a bit off-putting for some owners, and you may find that they. They sort of I'm quite happy with with what's left, even if the horse is is comfortable essentially and and happy doing its job, and they might often elect to .

Back off the work that they do because they just don't like the idea that the horse has a gait deficit. And that's obviously their their choice with that regard. So the horses, yeah, they'll never look normal, but they can certainly do a good level of work with this condition.

So the next condition that we'll move on to now is that of peroneus tertius rupture. I'm not sure how many of you will have seen this condition, but it's something that does stick in your mind once you've seen a case, as, as quite a a a cool diagnosis. Again, very sort of evident clinical picture, 100% possible to diagnose this condition on clinical examination.

And I think we can all appreciate that this is not a normal picture of a horse, even if you can't quite work out what's wrong about it, you can see that it's not, it shouldn't be like that. This horse's leg, essentially because the stifle is in virtually 90 degrees of flexion and the hock is extended, and as we know, the reciprocal apparatus should not allow that to happen. So back to a bit more anatomy, a review, of the relevant parts of the reciprocal apparatus is required to know why, why we have the, findings that we have with fibulars or perineus tertius rupture.

Perus tertius is a tenderness muscle. There are no muscle fibres in it, it's essentially a tenderness band that forms the . The cranial portion of the, reciprocal apparatus in the horse, so it links the function of the hock and the stifle on the cranial aspect of the hind limb.

It originates at the distal femur and. Runs down the cranial lateral aspect of the tibia sitting between the lateral digital extensor tendon and the cranialis muscle and the cranialis tibialis muscle, . Yeah, cranial actually.

It's at the level of the hock, divides and then inserts on the dorsi proximal aspect of the third metatarsal bone, . And so linking. These two joints, in, in motion, combined with the effects of the STFT at the back of the leg via its retinacular attachments onto the calcaneal bursa, as we've just discussed, but also, other things going on in the back of the leg.

So rupture of the fibulais tertius, as you can see disrupts that this function and allows independent flexion and extension of the stifle and hock joints. So usually, well, this condition can occur in any horse. It's a an acute, usually hyperextension injury that causes rupture of the ligament.

Spontaneous rupture can occur, or seemingly spontaneous, it can occur in falls and other animals, but usually there'll have been some sort of traumatic event. Occasionally there's a, a physical trauma, a wound over the cranial lateral aspect of the cruz which will. Of course, transection of the ligament directly, tendon directly.

Common injuries that would cause this is anything that causes forced extension of the hock when the stifle's flexed or vice versa. So putting that speed, putting a foot in a hole, that sort of thing, you're likely not going to know exactly what happened to cause the rupture in the first place. And you know we keep seeing these pictures.

I'm sure you've seen it in all sorts of textbooks and, and online. This is a Pythaonomic presentation if you're able to flex the stifle extending the hook, you must have, a pernius tertius, rupture. But it sounds daft to say this, but you will only, identify this if you do this test, and I'd certainly be the first to admit that I wouldn't necessarily attempt this in every hindlilous case that I see.

So. A few other clues that you that can point you in this direction, on your gait assessment of these forces, or perhaps this is a reminder if you're to, to try this on every island moments that you see, and you never know, one day, one of them might have ruptured its pony its tertius. Yeah, so, these horses walk, if you look carefully, if you stand on the side and watch, watch them walk past you, they will have increased hoc extension, more than you'd expect, or, or asymmetric in the hind limbs.

And because of the increased extension, you often see a little dimple at the caudal cross, so 10 or 15 centimetres above the points of the calcaneus on the back of the limb, and you just see a sort of little dimple where the. And there's more flaccidity in the back of the leg because of the increased extension of the hock. And if you see those things or suspicious, then certainly pick up the limb and, and, do this test.

So, so yes, in theory, easy to identify, but actually very easily missed because you may not do the, the relevant manipulation tests to identify it. And certainly I've common commonly seen horses that have been examined a few times before, before this is picked up and not necessarily surprisingly. So diagnosis, it is a pathognoic presentation.

Ultrasound examination, can also be helpful or allow you to visualise the tear. The proneus tertius is really easy to image, you know, it's not an area we scan commonly, but don't, let that put you off. It's the most eogenic structure on the craniallateral cross, and if you follow it, you'll see a rupture.

It's usually at the mid-level. The tibia occasionally can be distally sort of over the front of the hock. Again, image both limbs for comparison, but you will certainly see disruption, swelling, and, an absence of that academic, academic band.

Treatment again is conservative and has a good outcome. So 3 months or so box or pen rest constriction allows fibrous union to occur and restoration of the reciprocal apparatus function. Ultrasound monitoring is interesting to do.

Ultrasound scanning is interesting to do, but actually, the location of the tear, or whether there's a wound or not doesn't affect the outcome. There's no association been shown there. So really it's a case of giving these time.

It's just a small retrospective study of 21 horses, 15 of which returned to full work. I couldn't find the full details of exactly the details of these cases. However, my experience certainly is it's a few I've seen have done absolutely fine.

These 21 horses had a mean or 15 horses had a mean convalescence of 41 weeks, and those that did worse were the ones that weren't rested sufficiently or were diagnosed late. I guess those two factors come together. More than likely, and this is a great picture showing very clear extension of that hook and reciprocal apparatus failure.

So that's basically covers all of the, the main conditions. I wanted to discuss with you today. Just finally, I just wanted to mention, thinking about things that happen to older horses, certainly suspensory ligament degeneration shouldn't be missed out of this list, although there's not a huge amount to say about it really.

Suspensory ligament degeneration and progressive hyperextension of the usually hind fat joints is something that we do fairly commonly see in older. All the horses, and this really is due to progressive degenerative breakdown. Of the hind limb suspensory apparatus, there's rarely a specific lesion or injury and results in slow progressive over time, hyperextension of the hind joints, and they really can head very close to the ground in some cases.

Often horses seem very tolerant of this as a condition. They'll often be retired horses out in the field, and they seem to get by really quite OK. Almost, in every case it will be a bilateral condition, however, so a little bit hard sometimes to appreciate.

The exact degree of lameness that it causes. Most often these will be certainly older animals. I've seen plenty of warmbloods, ex- competition warmbloods, they've done a lot of work over there, time, and brood mares as well.

They often have a straight hot confirmation, and this may be secondary to previous more acute proximal suspensory desittis and changes in the suspensory ligament are evident on ultrasound scan, but more often than not, it's, it's more of a sort of degenerative lengthening of the suspensary, either at the branches or through the ligament as it degenerates. Allowing the flock to drop. It's more commonly seen in Andalusians and Pasophenos, perhaps as a slightly different pathogenesis, specific other causative factors or genetic predisposition hasn't been elucidated.

But these horses are certainly out there and you'll certainly be asked to manage them, or look at them. There's very little that can be done though, in all honesty. These are usually horses that are, retired and managed with analgesia as required.

Shoeing is often attempted just to try and help support the hind limbs a little bit. Planter extensions do make sense to support the, planter aspect of the limb. Often they'll also be put into heel wedges, which doesn't really follow for me as a particularly appropriate thing to do.

Certainly planter extensions do make some sense. And usually in these animals because their athletic requirement is low, that's really enough to just keep them comfortable and manage them, ongoing out in the field. So that sums up all of my the bits and pieces I wanted to discuss with you today.

If you do have any questions, I would be more than happy to take them now. Fantastic. Thank you very much, Rachel.

That was a great, tour through some of the, common conditions you wanted to, explore then and some real good food for thought as well. As Rachel says, we've got 2 minutes before, Russell, starts. So if anyone does have any questions, please do pop it in the Q&A box.

To see if anyone's got anything coming in, but no, that was really good. Thank you for that, Rachel, and, hopefully, I think, Russell's partners will be a good well rounded, afternoon of sessions. Oh, we've just got someone popping in here.

. Just an amateur thought, with old horses on them, sorry, I'm just see shorthands, so I'm just trying to decipher it. Thought old horse sus ligament degeneration I presume it is. Yeah, yeah, maybe they started life with relatively long low pasttern configuration.

WRT selection for their working life. Does that make sense, yeah, it does, and I think often these, yeah, there will be confirmational factors that will increase the likelihood of, suspensory degeneration or these old horses and, probably a, you know, a combination, not all horses will have long patterns, but, but, will, will, develop this condition, but. Yeah, absolutely.

I don't think it helps them increase lever arm, I guess. And, probably, yeah, and often, a finding in these kinds of cases. But of course, it depends on their workload as well and what they've done in their life and, how much strain these legs have been put under over the years.

No problem. Thank you very much for that. Thanks for asking that question, Henrietta.

OK, so, well, all it needs for me to do is say thank you very much, Rachel, that was great.