So thank you and welcome to the webinar on the approach to investigating horses with back pain. The areas I would like to go into today are the presenting complaints of horses with back pain and the behavioural manifestations. We're also gonna look into the conditions and causes of back pain and then really go on to the detail of the clinical examination and also look at the link between back pain and lameness in general.

In terms of investigating further, further, we're going to look at diagnostic imaging of the back and diagnostic local anaesthesia techniques, and I then want to finish off with some case examples. OK, so the behavioural manifestations of forces with back pain can be quite variable, and a resistance to attack is one of them, resistance to being ruined is something on frequently report. We will notice some pain and, and palpation of the back and there may be some reduced mobility, or even lameness on the lunge when the horse is being worked under the saddle.

The horses may show signs of poor performance, and that can also be very variable depending on the discipline the horse is working in, and then we also see some unwanted rhythm behaviours that may be even dangerous, such as rearing or bucking. What, most of these sort of behavioural manifestations of courses with back pain have in common is that they are not very specific. So I think if we are presented with a history or sort of starting to, to approach a course with suspected back pain, it's really good to stay open-minded.

And many of these issues and manifestations can also be produced by other problems, that, for example, resistance to attack, it could be the attack itself that the horse is resisting to. Or it may have some pain coming from the rib cage areas and it's even reported that some horses with gastric ulcers may exhibit signs like this. So staying open-minded, I think it's a good idea with these sort of fairly non-specific signs.

If we look at the conditions and causes of back pain, we have quite a few. So, initially, of course, we're thinking of causes of primary back pain, and on the top of the list, there will be the impinging dorsal spinous processes and there will also be the arthropathy of the articular process joints of the thoraccal lumbar spine and this will be ventral spondylosis. Or the mopathy of the supral interspinous ligaments, and we may encounter horses that even sustained fractures of the withers or any other parts of the spine, and we also see horses with myopathy.

But then there also cases with secondary back pain or conditions that may mimic back pain and a really, really important point I think here is lameness, not only hi lameness, lameness in general, and horses that have actual sacroiliac joint region pain or neck pain may just look like a horse that has a back problem. And then a really important point as well is the rider and attack inflicted back pain. So the horses with a poor saddle fit, or horses that are trained with unsuitable techniques such as the overuse of draw reins, the horse rider connection might just not be good enough.

There will be poor riding skills that cause the horse actual back pain. Excessive right of way is always a very delicate and difficult topic to talk about, and, I think, yeah, something to, to, to bear in mind in certain situations as well. And also the lack of horse fitness or strength, a case or cases come to mind that may have rehabilitated from a different injury and then going back into work.

And then I'll present her pretty quickly with some back pain. Well, that might just be a horse that has an underdeveloped back top line and that's just not ready for the job yet, and we have to sort of go back a few steps and, and train the horse differently. So, so just a sort of a different reason why the horse may, may develop back pain.

We start with the clinical examination. I try to have a systematic approach and really evaluate the horse with a perceived or suspected back problem just as any other orthopaedic case. So I will feel all the legs and the neck and the head.

And the pelvis. But, when, for, for the, for the purpose of this talk, so we move into the actual clinical assessment of the back. I think one important point is to remember that less is more here.

So being really gentle, trying to motion, palpate the voices and just see, how the Reflexes are how the horse moves away from pressure and what the muscles do while the horse is moving its back, always going back and feel the axial musculature here, while we look at the back and, sort of lumbosacral region and inflexion and extension. It gives us a lot of information. We can feel the dorsal spinous processes, and again, to feel Mobility, lateral lateral flexion of the back.

It's nice to hold one hand at the tail and then move the horse away. Also, the sort of punctual, moving, and pressing on from dorsally, shows us how supple and how loose the horse is and how the muscles and the horse itself reacts to this movement. And at the end here of the video, I put some pressure on the spermum just to arch the back up a little bit and again feel across the muscles and see how the horse goes with the movement.

So to me, this would be a good example of a, a nice and normal back of a normal horse. And then something we encounter very frequently are these hypersensitive voices. So, we approached the horse of the horse's back and gently palpate.

Over the back and you see the sort of twitching and moving away, even just with the, with the fingers. I find these clinical signs, or these reactions of the horse, in terms of hypersensitivity, really quite difficult to put in a clinical picture. And I think there's a lot of room for overinterpretation.

Equally, it's nothing we want to ignore because hypersensitivity might just be that sign that the horse has got a sore back. So I think it's a clue, but it's something to look into the, big picture, and, a good reason to, to try and collect some more information about the horse. Some horses are really apprehensive as a.

In the back and I think that's commonly the case in horses that may have already had some, some other or many people look at their backs and treat the backs, and I usually sort of leave it till last, so I'll palpate the legs and everything else first, and then sort of carefully go to the back. And, you know, the subjective impression that we sometimes get is not always easy to put in the whole clinical picture. We need to be careful not to overinterpret here.

A little bit easier to interpret. I find horses that exhibit some spasm of the axial musculature. And this pony had that, so with a little bit firmer, but gentle, so, but the firmer pressure with the sort of front part of your hand.

You, we can move along the back on either side, on the left and on the right. And you can see that muscle twitching there and what you Feel when you feel over the back here, there's some reasons of hardening of the muscles. And what helps me to really go into the depth a little bit more here is to do that zigzag serpentine movement across the apexxial musculature, to feel for, for areas that are firmer than others or where we get some more reaction than in other areas.

The dorsal pressure, and that's the same horse as you can see. Can sometimes be also repeatable and therefore, in my opinion, more reliable. So here, putting some pressure from dorsal on the cranial lumbar area, the horse tolerates the movement really well.

And if you go a little bit Further caudal, you have a very clear pain response, and the horse tries to restrict the movement and go against it. If these signs are repeatable, I think this is a little bit more to go on and gives you more of an idea where to look next to investigate that case further. From the static physical examination, we now go to the dynamic assessment and we look at the horse moving, and here, it's important to also look for lameness.

So I'd like to see the horse in hand, walk and trot in straight lines, and then see the horse on the lunge, ideally on different surfaces on the soft and on the hard surface. It's a nice idea to see the horse, lunging with tack, but without the rider. It's also a good moment to see how the horse reacts when it's, when it's being tagged up and a good way of safely assessing the horse with the, with the tag.

Of course, the written examination is really nice and if at all possible, I will do the written assessment, but, in some horses, it might just be too dangerous and we have to come up with other ideas here. The problem or the interaction between back pain and lameness is really common, and in this study by Landmannal in 2004, they looked at a population of 805 horses with orthopaedic problems, and they found that 74% of horses with back pain were also lame, and 32% of the horses with lameness also had a back problem. So, therefore, I think it would be a mistake to trying to isolate a horse's back and don't look anywhere else.

It's important to stay open-minded. And what was also found in a different study here from Cava from 2017 that lameness reduces back mobility. So we see these horses that have a a rigid back and, some of these horses, when they have the hind limb las blocked, like in, in the study, they will increase the range of motion after having the hind limb las blocked.

Yeah. So here, the, the, mechanics and the movements of the horse and the front and the hind and being connected. By the back, is something, really important.

So we should always perform a gait analysis on whether that's subjective and or objective. And if we do find an asymmetry, for example, in high limbs, we should not overlook it because it can be very frustrating to treat the back first and still have the high. Lanes and always having to go back because the only thing that can happen if the horse has got back pain because of a hind limb asymmetry, gait asymmetry, it'll only come back every time after treating and without actually going into the, the main problem, which might be in some cases the lameness, you won't be able to treat the horse's back pain successfully.

I'm lucky enough to work with an inertial sensor system, and I really like using it on horses, and I think it becomes more and more available these systems that you can even use with the horse on the rider here on the left side, and with some systems you can even assess the back mobility. And that might just give you that extra objective information that you need to get to the bottom of the case. These are images of the regates his team, by Til Luau, who's based at the Royal Veterinary College in, in London.

So lunging with tag, I've got this horse here as an example, and we'll come back to the horse's story later in the cases. But, what I can say is that this is not a youngster that has got the sadle on on the first time, and, this can just show how useful it sometimes is. So this horse was already assessed and had no, overt lameness or abnormalities.

It was lunged in that pen before without the saddle on. And I, once the horse is moving, you'll see. That the voice now is really quite reluctant to go forward when it does.

It's has a very irregular movement, it's tail swishing and just looks in general stressed and unhappy under the saddle. If you then ask the horse to do a little bit more, he just goes into the canter, it starts poking and then goes into a bronking movement as we might know it, from horses that have the saddle on for the first time. So, you know, we'll, we'll talk about this a little bit more, but of course, this gives you the basis.

This would be too difficult to see under the saddle with a rider board, but like here, you can now try different saddles, different paths, maybe just, just A normal lunging girth to, to look at the horse's reactions and, and see, and you could even from here start and, and do some diagnostic local anaesthesia on the lunch if it is repeatable and you can rely that every time you put the saddle on the horse does this movement. With the examination, I find really, really important because some horses will only show how bad lameness when they are actually under the saddle and before on the luncheon in hand, you don't see it. So for that reason already, it's, it's important, not to miscellaneous, that's relevant under the saddle.

But also you can learn a lot about the horse rider relationship and how, how things go and just sort of see the signs. And I just picked this voice because it shows some very clear signs of sort of unwillingness, and, is rearing here, tail swishing, and, despite the riders of being quite strong about asking the horse going forward. It keeps on, on doing, doing this.

What I think is important here that yes, we see an unhappy horse, and it's certainly showing some unwanted behaviours under the saddle, but it doesn't have to be a back problem. This horse could also have stifle pain or neck pain or tooth problem. It could have a poorly fitled saddle or it might just not like the pushy style of the rider.

So again, here, yes, we can see the problem and that's an area that we can work with and investigate further, but It doesn't necessarily mean that the horses back pain, and I think that's something that comes off from the rider or from the owner. The problem is only there when the riders on the horse or the, the, the, the saddlers in the back. Therefore, it has to be a back problem.

That's often not actually the case. So once we've collected all the information from our clinical examination, the question is what should we do next? Should we go into imaging or diagnostic local anaesthesia?

And I think that's something to decide individually in each case. So if I had an, an obvious lameness, then I would certainly attend to investigate that further and diagnostic local anaesthesia might be a good first step. If the signs are very unspecific, or I have an area where I have an abnormal clinical finding that I'm convinced about, then diagnostic imaging might be a logical next step.

So looking at the diagnostic imaging of the back, we can apply the standard modalities, radiography and ultrasonography. And we also have an advanced imaging modality cytography to evaluate the the spine. Starting with radiography, we want to visualise the vertebral column with the dorsal spinous processes, the intervertebral articulations, and vertebral bodies, and we can acquire lateral lateral views and also oblique projections.

The image quality is variable, usually in the more cranial part of the spine, better than further caudal, and that depends very much on the equipment we use, the breed we are looking at, and the body condition of the horse, bigger horses being harder to image here and getting some good, good quality of all the structures. This would be a setup of the sort of standard 3 images that I would do in a standard case. I like using coins as radio page markers so I can refer back, from the radiographs to the horse and see where, where a potential problem is.

We want to do overlapping radiographs so we make sure we've imaged all areas. So if we always have the two coins in the picture, we can be sure we haven't missed any, any parts of the spine. And this is how the sort of 3 images would then look like.

And if you have any clinical indications of looking at the withers, might be worth going a little bit further cranial, like a very flat wither area or anything else, . Sometimes it's also nice to see some vertebral bodies a little bit further cranially, further caudal, the image quality usually isn't good enough to, to see much depending on your horse, but in some horses, you can also, just sort of go and and go all the way back to the sacrali to image, depending on the horse's condition. So what we can see here quite nicely is the dorsal spinous processes here on top, and then below we've got the vertebral bodies, we've got the ribs and sometimes we can also get some idea even on the lateral latervis here of the intervertebral articulation, or at least on the very ventral aspect of our interspinal spaces.

If we are interested in a particular area and we want to zoom in a little bit, it's nice to collate a little bit to reduce scatter so you get a nicer picture and you are able to assess the bony structure of potential signs of impingement a little bit more closely and then a little bit more detail. In terms of assessing the space, the interspinous space, and the distance between our dorsal spinous processes from lateral to lateral radiographs, we have to be a little bit careful. There are a couple of factors that influence the appearance of the radiographs, and I think this paper from 2016 showed it really nicely.

They worked on cadavers here and had acquired lateral lateral radiographs and also CT images. And they took sequential radiographs of each dorsal spinous process and focus and performed measurements. And then they found that well they, they, they evaluated the effect of the geometric distortion by having a focus spot.

X-ray beam, and obviously, the only one space being positioned central to that, and everything for cranial and caudal positioned further out. And they found that this distortion markedly affected the appearance of the interspinal space. Yeah, and this is, what, what this diagram shows here, sort of images of interspinal spaces, despite them being the same size.

Theoretically on the horse will look smaller, the further away they are way here from the from the X-ray or from the centering point of the X-ray beam. So, it's the position, where are we centering on? That affects the appearance of the, space.

And then here you can see quite nicely that also the shape of the dorsal sinus processes will affect that appearance. And on top here, we've got the lateral lateral radiographs and on the bottom, we have a, a transverse section of the interspinous space sort of looking onto the DSPs from the top. And if we just take the, the last one as an example.

If we are centering here on the interspinal space, we get that picture, sorry, here, we get that picture right in the middle. And this sort of is, is, illustrating the size of Get a small space only. If we centre a little bit further cranially to the left here, and it's on the side because of this oblique shape, here we shoot directly across this, and we have in this case, a larger space.

And if we then X-ray from the caudal, there's hardly any space, yeah, no, no space in that area. So it's not only where we centre, it's also the the shape of the dorsal spinous process that can be variable that will affect the appearance and the size of the interspinous space on our radiographs. And another factor that influences the distance is the head and neck position.

If we have a low head like in the middle picture here, the, space will be bigger if we have a high head position of the opposite effect. And we'll have a decrease of interspinal space and to be able to compare before and after treatment and in general between horses, I think it's a good idea to aim for a neutral head position where we position the, the muscle at the shoulder height. And I think what also should tell us here is That, yes, we can say that there is some crowding of the dorsal spinal processes, but going in and measuring them and really going from a millimetre or to a centimetre, a specific, I don't think we can always be that specific because there are too many factors influencing the radiographic appearance, so we should be careful with that.

From the lateral later radiographs, we can also move on to oblique projections. this would be a lateral 20-degree ventral lateral dorsal oblique view, and, ideally we send a 15 to 20 centimetres ventral to the dorsal midline and align the x-ray plate perpendicular to the beam. And as close as possible.

And we will encounter in the thoracic spine, some superimposition of the ribs, and they're highly curved in that area. And on the lumbar spine, we would have some superimposition of the transverse processes and abdominal structures, which makes the assessment here require the oblique views very, very difficult. And radiation safety are put here because We usually need some quite high exposures, and they're also not the easiest images to do.

And I think it's, it's definitely something to, to bear in mind, but I personally don't do them routinely, on every horse I X-ray on the horse's back. The appearance of these antivertebral articulations can be quite variable, again, depending on the technique and, and equipment and horses, and I find it makes comparison and interpretation sometimes quite difficult, especially if we're dealing with only subtle changes. So certainly.

Challenging image to interpret, in my opinion. Here, this would be an example of a normal horse of the caudal thoracic intervertebral articulations, and you can see the joint spaces here, quite nicely. These are the ribs that we set that are sort of in the way and dorsal spinous processes here.

So that will be on a bleak view. Looks like. Sometimes, what is a little bit nicer is if you have a bit of a bigger sort of field of view and you get them all next to each other, it's a little bit easier to compare.

So again, another example of a, a normal horse here without any significant radiographic changes in the intervertebral articulations. So what are we looking for on the radiographs? We look for remodelling and crowding of the DSPs, the dorsal processes.

We look for. The models, facet joints already on the lateral lateral radiographs and potentially on oblique views, we look for ventral spondylosis and for possible fractures. The DSP or the degree of impingement can be quite variable and so can be the reaction that's formed by the impinging bones.

Here on the top right corner, we've got a mild impingement, but already with a sclerotic rim here at the back, of, on the caudal aspect of the process. Then we've got moderate changes where we already got some lytic areas here that you can see this sort of around radiolytic parts and then here an example of this was we will see later again in the cases is really quite severe overriding dorsal spinous processes and marked remodelling changes. This is a horse with examples of the remodelling of the intervertebral articulations and very ventral aspect of the interspine spaces already visible on the lateral to lateral radiographs, so.

Here on this radiograph, we get some osteophyte formation, remodelling, a new bone formation on these joints and you can see that they look certainly different to the neighbouring joints on that area. This is a horse with ventral spondylosis, so we get new bone formation on the ventral aspect of the vertebral bodies, and usually what you can see is some different stages of the disease. He, the, spondylosis makes it very mature and rounded appearance where here, the bony bridge looks a little bit more regular.

And here you still have some sort of space there. Sometimes, you obviously have the overlying lung pattern which makes more detailed, structural evaluation of the bone, difficult, and, but this would be a good example of a horse with quite extensive ventral spondylosis that affects, at least 3 spaces here in that image. OK, from radio radiography, moving on to ultrasonography, can we scan there?

We can scan the supraspinous and interspinous ligaments. We can look at the bone surface of the dorsal spinous processes. Can we get another view of the thoracic and lumbar into vertebral facet joints, and, in my hands, well, in my opinion, a really nice additional way, to, to look at these joints and quite sensitive to, to obvious changes.

And we can also look at the apexio musculature. So starting with the supraspinous and two spinous ligaments, this is here a video, so we place the probe and longitudinal orientation midline. It's really, really important to make sure that we scan in between the processes.

So what we want to see is the Hypereogenic line and the interspinous ligament in between and the supraspinous ligament that pulls along here. The reason this is important is that if we scan off to the side like illustrated in this picture, it would be the number one, so the probe just off midline, we still get a very beautifully longitudinally fibered pattern here, but this is actually the fascia of the musculature rather than the supraspinous ligament that we actually want to look at. So here in position 2 when we are midline longitudinal orientation, we can see here there's the surface of the dorso spinous process and the ligament running in between.

There are some anatomical variation, variations to be aware of. So in the cranial aspect and the thoracic spine, the supraspinous ligament appears thinner, and also a little bit wider, whereas towards the back, towards the lumbar spine, the subspinous ligament is thicker, therefore also a. But narrower, not to be confused with swelling of the ligament in the lumbar area.

This is an anatomical feature of it that, it, it gets thicker and usually also more homogeneous for the caudal, probably due to the curvature of the spine here at the back. And what we can assess longitudinally, we should also assess transversely, and this is a video here, again, moving from cranial to caudal, from process to process and looking at the supraspinous ligament. In between.

It's always helpful to tilt the probe back and forth and I, as you can see, it's frequently also a heterogeneous appearance and we should be really careful again not to overinterpret that. A lot of horses have a heterogeneous appearance here. And also it depends a little bit how we tilt the probe, so especially in that saddle area, to get the probe on incidence, like on the left side here, you would have to tilt your probe forwards a little bit.

This is the exact same space on the. Right, but with the tilt sort of, perpendicular, to the floor. So this is the kind of, tilt you want slightly towards cranial, to get the image on incidences, and, and, to fully evaluate that area.

Possible findings there on the supraspinous ligament, maybe a loss of longitudinal fibre fibre pattern, the very common heterogeneous appearance and some ulcers even show some anthesophyte formation. As you can see here at the bottom, you can see the sort of little hooks that are formed on either side, where the ligament attaches on to. What we should really be careful is sort of questioning the significance of these findings, .

And put it into a clinical, perspective. Some of these changes can be quite marked, but it needs to fit with the clinical examination or other, findings that we have so far in the workup, and if in doubt, it's always good to potentially perform a diagnostic block. Of that area.

To sort of determine a little bit more the clinical significance of these heterogeneous of the heterogeneous appearance of the supraspinous ligament in the saddle area. this study was done. They had 3 groups of horses, they had Horses, with, unrelated, back pathology, and ridden horses, and unridden horses, and, they, the hypothesis was that unridden horses were less frequent.

Affected by changes in the supraspinous ligament, and then the other two groups, and the results were that there was actually no significant difference, and the majorities of findings were in the area of T14 and T17, so that that typical cell area. The question is a little bit, why does the supraspinous ligament appear that way in this region and the thoughts are that horses might just have demitis without any clinical signs in that area, that, that is possible, that we might actually deal with enough incidences artefact, frequently in that area. And it might be due to the supraspinous ligament fibres not being under tension in that part of the curved spine.

It might be a specific exercise or saddle that's used that's causing these changes, but, certainly some, some more studies with, with higher numbers needed to establish that a little bit further. But what we know at the moment is, a lot of forces have that without having problems. So before we jump to a conclusion, it's good, to, to put the, put, put the signs all together and confirm potentially with the diagnostic block.

What, becomes a little more interesting is if the area of concern, is very focal. So, this was a horse here that had, confirmed back pain in the area where there was a change, so this is the normal fibre pattern here, of the dorsal spinous process that's a direct neighbour. Going one area a little bit further cranial, you see that large anechoic area here where the supraspinous ligament runs to, so going comparing the neighbours, if the one in front and one behind look very different, then it's more likely to be significant here.

Other findings might include very subtle changes, so this was of course with back pain in that area confirmed by diagnostic local anaesthesia and on the radiograph, we found that really a small opacity here and so we zoomed in a little bit, you can see this really small round area. Potentially of mineralization within the ligament and an ultrasound, you can pick that up. So here we've got the dorso spinous process here and here, that's the ligament and this hypereogenic area represents that small area potentially of dystrophic mineralization.

Within the ligament. The dorsal spinous processes, with the ultrasound, we only have a very sort of superficial view of them, and ultrasound certainly is no substitute for X-raying. We sometimes see are these sort of, separate centres of ossification.

This is a horse here that has this sort of extra hyperagogenic areas there. This is the dorsal spinous process, an extra line here again here and here. Sometimes, not always, but, often you could see on the radiographs the same findings, and this is most likely physiological and these are cartilage caps with separate centres of ossification.

Study by Hoer in 2005, a third of assessed horses between 3 and 7 I had exactly these caps. Other studies were questioning whether that's an insertion or calcification or sort of flakes of lifted off, perioste to trauma. in my opinion, this is more unlikely and I think, it's more likely to be physiological.

Because in spines, it's it's, you can sometimes see a sort of narrowing of the space, but because we can only see the surface and we've already seen that the shape of the DSP can be quite bearable, . It's just, you don't, just don't get enough information to have the full story. So I think ultrasound should always be combined with with radiography, even if we use a probe going really nice and low to the ventral aspect, it might add some information to ultrasound scan this, but I think it shouldn't be used in isolation.

For, for these conditions affecting the dorsal spinous processes. Thoracic and lumbar intervertebral fosset joints, we need a convex probe for this area. We have to go quite deep, scan, scan very deep, and also here there are differences in horses, some heaviert warm bloods.

You find it very hard to get a nice picture, as in most thoroughbreds, you get, get a very nice detail on the joints. It's important to remember the anatomical differences of the facet joints in the back, so the, in the thoracic spine, the joint is positioned very close to the dorsal spine is processed, so very axial, and has a very large mammary process. You can see that here in the specimen.

So in the specimen, we, we have a view from dorsal. These are the dorsal spinous processes. These are the facet joints and these are the mammary processes and right next to the GSP there's already the joint space, and here's some, some remodelling of the joint.

And moving on to the Lumbar, spine, you can see that the joints move further away, sort of, yeah, further away from the dorsal spinous process and, we can get a, a slightly different view and a different appearance ultrasographically. And this is what it looks like on the ultrasound scan. This will be the position of the probe.

Then you can see the dorsal spinous process here, here would be the rib area. This would be the mammillary process. And this is actually the joint space.

It's very close to the DSP. Whereas on the lumbar, spine, you've got your joint space here and you've got your articular processes right in this corner of this sort of, yeah, it almost looks like a little box, and next to the dorsal spine is process and the transverse process here. Mm.

You can even determine if you have a really good picture, which one, which vertebra is affected, it's the caudal or the cranial, articular facet here. So sometimes you get really, really nice detail. And then you can also assess the joints in the sergen plane by positioning the parallels with the midline.

You have to be careful not to confuse the joints with the ribs or the transverse processes, so you need to be really, really close. To a midline to visualise these and then you have the joints and you can assess the size and shape and compare to the neighbour. So this would be a horse with an osteoarthritis and the lumbar articular facet joints.

You can not only see the difference between left and right, so you have an enlargement of the joint compared to the other side, but you can also compare to the neighbouring. 4 or 5 here being a lot larger and more regular than the neighbours in front and behind. And this would be a specimen how it looks like and this is why we get the picture.

So you get a much larger facet if you have an arthritic joint, whereas with the normal joint, it looks nice and neat and you've got this little box here, as we imagine it or we can see it on, on the ultrasound. Arthritis can be quite severe, and I think we can then imagine how painful that condition is. Here, it's it's even ended up in a in a fusion, of the joint there, and it usually has also an effect of on the neighbouring joints by mechanically, but also, it's not uncommon to see horses that are, have many joints affected and also on both sides.

So this is how, how a severe case would look like. Again, really some marked severe enlargement compared to the neighbour who's really only half the size and also not only enlargement, but even a sort of, yeah, a convex area of, of a hypertrophy of the joint surface here. So ultrasound, I think in the right case, with the right, with the right horse and a good image quality can be really, really useful to assess for osteoarthritis of the facet joints in the back.

So, centigraphy is a nice advanced imaging modality that we can apply to horses with back pain. And it's important to remember what we are actually looking at. We're getting information about the dynamic processes of bone modelling and remodelling, which may be adaptive or pathologic, but it doesn't always have to be associated with pain.

So again, just another puzzle piece and certainly not the answer to everything. And also not In the back, but it really helps to further assess radiographic and autosonnographic findings, maybe to decide how likely it is, that these findings are clinically significant. It allows us the assessment of the whole spine.

It's useful in large hos where we don't get, the chance to ultrasound scan and don't have nice image quality on the X-ray. And it certainly is also helpful to rule out other pathology that commonly Mimics back pain for such a sacroiliac pain and the sacroiliac joint really being only imageed entirely by, by centigraphy. Yes, there are parts that you can scan, with an ultrasound scanner, but, cytography being a way to, to rule sacroiliac, pathology, certainly out.

It's easier in that area and therefore important. We acquire several images here to cover the entire back, and that may also be dependent on what, what we are, suspecting, but at least we want 3 images that again are superimposed or not superimposed but overlapping to ensure we Look at the entire spine. It's nice to have large parts of the ribs there as well, because also that can be a problem.

And so then we can do additional views if we suspect some problems and we have some dorsal views and especially in this area, you can hear see the lumbar spine, the transverse processes. And the facet joints would be on either side here of the DSPs, which are the the black dots here with the marked uptake and this is a really nice way of visualising the, the facet joints as well. And then going further cranially here, you see the ribs, so that being the, the, the caudal aspect of the thoracic spine.

And here in between the shoulder blades. We get a good spot even also of the very cranial part of the Of the spine of the thoracic spine. Increased radionuclide uptake associated with the DSPs comes also in different severities.

We may get some mild generalised uptake along the spine. So normal would be that we don't see any uptake here. With us, we always get some, but here in the area, we shouldn't get any, so we might have some generalised uptake or there is some moderate focal uptake on the dorsal spinous processes here or we get some mild multifocal uptake.

We sometimes see, especially in younger horses that may be due to that separate centre of ossification. This is a 6 year warm blood is that we do get some multifocal uptake in the area, but the image quality, if it's good enough, you can see that the outline of the dorsal spinous process is here and you get the impression it might not be that close. To be sure, in these cases, I would always recommend doing an X-ray, to be sure, and this is actually the correlating radiographs.

This horse has got no impingement and no kiss, no evidence of kissing spines, but there's just some activity here, in the dorsal spinous processes, which is what we see on the centigraphy images. An example of increased uptake in the interverteal articulations, we can see here. So this is the right side, that's the right kidney mass out and we can have here a focal increased uptake of a lumbar facet and we've got some bilateral problems here, but that would be an indication that there is an increased lunar modelling associated with the facet joint, in the lumbar spine.

There are several studies who looked at centigraphy and radiography, and in this study from Zimmerman and I from 2011, they looked at 604 horses that went underwent centigraphy and radiography of the thorac lumbar back, and they found that the severity of the radiographic lesions were associated with the sintigraphy abnormalities. Again, T14 and 17 were the most commonly affected. They found a breeding age effects, so especially thoroughbreds and older horses were predisposed for findings in these areas.

And what's interesting is that severe DSP lesions were more likely to have osteoarthritis in the antivertebral articulation. So if there's one problem in the back, we, frequently see also other pathology going along with that. And, what's also interesting is that some horses with radiographic signs of kissing spines had no increased uptake associated with the TSPs, sort of giving a little bit of an indication whether Centigraphy can help us differentiate between the kissing spine lesions that are active versus the ones that are not active.

So potentially something to think about. In this study, the group tried to put it into a, a connection with the clinical setting and the clinical pictures, so they had 582 horses that were presented for perceived back pain, and they found there was a significant association between the severity of X-ray changes and back pain and the severity of increased uptake and back pain. They also found again that horses with facet joints were more likely to have back pain than horses that just has had DSP impingement.

And the horses, the highest likelihood of back pain with the horses with both DSP and impingement and facet joint away. So, a connection of pathologies makes it certainly more likely, that the horses also have back pain. So once we've collected our imaging findings, we might want to check how it fits in our clinical picture and diagnostic local an analgesia is a really good way of doing so.

And I just wanted to sort of go a little bit into detail of the back injections. We can do an interspinous injection and here the preparation would be. To determine the exact injection site, so there's always good if you have used coins, or any other radio peg marker to refer back and then you can clip the marker and then, refer back to the holes from those.

We can identify the actual injection site by palpation, but I really like to use the ultrasound scanner just to make, make sure and mark out where, where exactly I'm going in. Of course, the usual aseptic preparation. We performed, I always wear sterile gloves, and what I really like is to use a small subcutaneous lab of local anaesthetic under the skin at the injection site.

5 mL or mL of, of local anaesthetic is enough. And if you use these 20 gauge needles, then horses don't really react to that. Whereas the bigger needles that we use.

And for the interspinous injection, they do react. And I find you can work much more precise and it's a lot less stress if you use that. And if you want to block a horse, you obviously want to avoid to also sedate the horse, because then later on, you don't know what actually made the difference.

So to me, the subcutaneous bloods for these injections really, really help, to have a horse that's, that's behaving during the injection. The needle size you want to use is at least 20 gauge or bigger, because otherwise there's a risk of the needle breaking off. And I like to use 1.5 inch long needles, but depending on what you want to do, you might want to use larger needles.

There are a couple of different approaches that you can use. I like to work with the midline approach where only in the one needle, midline, push it under the skin and redirect under the skin, to the left and to the right. The advantage is that you only use one needle that you redirect.

But, in some cases it might be easier, other people might prefer and that's also a very good option to use the two needle approach where you place one needle to the left and one needle to the right of midline for the injection. And what we want to do is power median injections at the level of the interspinous space to the left and to the right. And this would be a video of the sort of one needle approach.

So, going under the skin and then moving the needle across to one side and trying to go sort of fairly perpendicular to the floor, . Into the skin, inject, most of the local anaesthetic deep and then the rest as you pull out, and then redirect the needle here, tenting the skin, a little bit, pushing it across and placing the needle on the other side and repeat the injection on that area. Well, so, and, especially here, if you use a local anaesthetic web, you don't have any problems redirecting, most horses don't mind at that area.

Another option is to inject the intervertebral articulation articulations and for that you need an ultrasound guided injection. It's a deep injection, so we need a spinal needle as well, and that's an approach to use for medication of an arthritic or affected joint. Here, you want to get your ultrasound image again.

So we've got our joint. Here, ultrasound, probe, position that way, the needle would come in this way. It's, not necessarily a true articular injection, but you want to get as close as possible, so you want to make some contact with the bone and also stay within the border of the multiitous muscle here.

And that's the sort of red just highlighted the area. I want to aim for, nice and deep. So this is how a video would look like of an injection.

You can also do it by positioning the probe closer to midline and the, needle on the other side. I find it easier that way because I always find it very surprising how close you actually have to be to midline. And, then we, under the ultrasound guide and place the needles on the left side here.

Now, you've got a video of the needle, going in. So this is the needle here. And you can see it's too flat, so you have to go steeper.

You want to be, at least within this area of the multifidus here. This is the bone. So redirect the needle pulling out again and going again deeper.

Now, the needle is a lot steeper, going down and actually hitting here bone and hitting contact and here you can, you know, you can inject. Your medication and you are in the right spot. So that will be an ultrasound guided injection.

Of the intervertebral articulation. In the back. OK, so moving on to some case examples.

And to start with, one was that we've seen a radiograph earlier already. It's a 2 year old thoroughbred racehorse in training, and the complaint was that the horse showed a recent drop in performance. The horse was referred for a whole body bone scan at the train's request, but the clinical examination at the clinic found that there was some mild left fall in lane as grade 1 to 2 out of 10.

And we were surprised when we found the centigraphy images here. And you've got some really severe increased uptake on the dorsal spinous processes here which then prompted us to take an x-ray and this is the x-ray we found. With really marked overriding, dorsal spanish processes, marked bony remodelling, cystic lesions, and yeah, definitely one of the worst facts that I've come across and this, this case was interesting because we really only X-rayed because we found this, this increased uptake.

What we also found bearing in mind that left for limblaus is that this horse had some increased uptake associated with the middle carpal joint, with the radiocarpal bones here on the medial aspect on the left more than on the right. So this is the left carpus from a dorsal view, this is the right, and this is the hot spot here. And on the radiographs, you could see that there was some remodelling and some sclerosis of the dorsal aspect of the radiocarpal bone, a really common sign of racehorses having a metal carpal joint disease.

When we blocked the lamus. It could be localised to the middle carpal joint and was 100% positive. And I picked this case because, it's unusual in its severity of the back finding, but not too unusual that this horse had a different problem despite the severity of the X-ray finding, because the reduced performance improved following treatment of the middle carpal joint disease.

And the back seemed to be for this horse in this case, not the main issue to fix the poor performance. And also in the history that everyone was surprised that this horse had some, some, some back issues or some back findings, and I think for other cases it tells us to, even if we have obvious findings like kissing spines, especially. We should stay with an open mind and make sure we always link our imaging finding with the clinical picture.

And For that, we can use diagnostic local anaesthesia, definitely. But sometimes that might not be possible, either because of the area that we found the, the problem or because of the horse's temperament or because of the clinical situation. So sometimes what really helps is to do a trial medication, or medicate the horse and then assess over several weeks whether the behaviour or the problem improves.

So certainly something to think in mind or to bear in mind if diagnostic local anaesthesia is not an option. Case 2 is also a case that we've already seen, so this is the bucking bronking horse and The story of the source was that it was presented in summer 2014. For the investigation of a suspected back problem, and the horse has been under saddle, everything fine, and then started to be reluctant to go forward.

That got gradually worse and it's then started showing signs of signs of this cold-backed behaviour. Clinically, the horse seemed to have some pain arising from the, from the back. It showed no significant signs of lameness.

X-rays of the back were without any findings and also ultrasound of the back of pelvis were normal. And I just wanted to draw your attention here to this image. So this is the back here, and I just wanted to show you the ventral aspect of the vertebral bodies without any signs, no, no abnormalities.

So the question then was, OK, what to do with this case, next, we certainly tried launching this with different tack, and every time we got a tack on, it reacted, so even different saddles, . And we discussed a be test. I think that's also something to consider maybe even prior to referral where you medicate the horse with nobutisone and the horse continues to carefully exercise and you see whether the behaviour changes.

And this is something that the people Actually, went for. Of course, intigraphy, was also something that, I would have recommended in this case. Written examination, I would have hesitated because of the severe behaviour of the horse and diagnostic local anaesthesia was something that we sort of discussed to be, to, to do on the lungs potentially.

So, we opted for the cortisone trial, and that will be the dose that I would give for these days, so 2.2 milligrammes per kilogramme body weight, twice daily for 4 days, followed by 2.2 milligrammes once daily for another 10 days.

And then While on the medication and also once you take the medication off and see does it improve on the medication and does it deteriorate after finishing the course. Really big problem is the objectivity here and yeah, it's always worth talking, talking to, to clients about that and or or to whoever assesses it at home, because they know they are feeding a medication to stay as objective as possible. So the trial turned out to be positive, according to the owner.

But then we sort of lost touch a little bit with the case, and they did, a few further inventions, interventions at home. Sintigraphy would have been our next step. At that time, they couldn't decide to go for it.

But they also found that the, poor performance didn't improve and the behaviour didn't improve. And June. 2015 repeat referral happened for antigraphy in that case.

And this is what we saw here, and I was really surprised because we have some really quite marked increased uptake associated with the ventral aspect of the dorsal spinous processes here in the saddle region. And of course, if you remember, on the radiographs, we had no signs. Of course, in the first, I thought, oh, have we missed something here?

So I went back and couldn't see anything. So we X-rayed the horse again and what we found, sure enough, is also some clear bone remodelling here on the ventral aspect of the vertebral bodies. So this horse had a ventral spondylosis, and it's an interesting case because we actually picked up the horse while it was forming it.

And before we had some radiographic evidence, at least, it would have been interesting to know whether there would have been already some, some sintigraphic. But radiographic evidence, there was no, no sign of the ventral spondylosis. And usually it's quite difficult to establish the clinical significance because as we know, ventral sponylosis might be an incidental finding, but it's also known from other species that ventrospodylosis can be very, very painful, particularly when it's forming, so, at a young age.

And as much as we have to make sure that we rule out other causes and, and cases here, it really all make, made, made a lot of sense. Unfortunately, no specific treatment for this area, because something we don't really have access to on the ventral aspect of the spinal column. But, yeah, interesting case here where we have a significant spinylosis form with only 10 months.

So always worth to go back to the cases if we don't see anything or, as I say, consider some advanced imaging if the X-rays are unremarkable. Case number 3, we've got a 12-year-old crossbred mare, and it's used for general riding. It's been in the owner's possession for 6 months, not uncommon for us to find these horses, when they show some written behaviours after they changed owner.

The campaign forced that the horse showed some discomfort when ridden. This is the sort of horse's appearance here. So, What I wanted to point out here is that is that the musculature of the hind end and so on is, is acceptable, and, also the, the top line is acceptable for a general riding horse.

The palpation here of the back was normal at the beginning, was a normal range of motion, really nice and soft, muscle, and really not much to remark on. When we then moved on to see the horse in a in a dynamic scenario, to see the horse trotting away. You might see some subtle right behind the lameness.

Yeah, . When the horse comes trotting back towards us. You might just show a subtle left fallen asymmetry.

Certainly not very much to go on. On the left brain, on the heart, left for limb name is a little bit more obvious. And here on the right vein, we also have a slight right fall and lameness.

And a slightly shortened stride on the right hand as well. On the soft surface, maybe you can still see a hint of a, of a left forelimb here. And on the right right here some mild right hi and lameness.

The cancer, yes, not very much in portion, but again, you sort of always have to remember what kind of forces you're looking at. But what we did notice, was right at the first sort of lunging, the, even though we did only a few laps of cancer, the horse starting to sort of breathe heavily and it could certainly be unfitness, but, It was sort of the more the horse moved, he sort of, the more reluctant he was to go forward. And then you can see the sort of wide nostrils here and sort of slight distress sort of facial expression.

And, when we looked at the horse and the saddle, again, it started working OK, maybe a little bit rushed. . And then it started.

Being reluctant and starting with some tail swishing, and then really sort of obvious here, sort of bucking and not wanting to go forward. And this really got, despite the rider. Being fairly firm.

Trying to push the horse on, he sort of would go again, but the clinical signs got worse and worse. The more laps the horse did. Directly after the exercise, the horse was unwilling to move, so where it stood, it stood.

It wouldn't move around anymore. It's made a stiff sort of back appearance, and when palpating the back, you suddenly get that twitching and also some pas in your muscle spasm. So as the next step, we X-rayed the back and there was some mild impingement of the dorsal spinous processes here.

But also some very subtle reaction. But because of the signs getting worse with exercise, we checked out, the muscle enzymes and what we found here was a sixfold increase of AST and a 23-fold increase of CK. And I think this is a good case to remember that muscle pain, and also exertional myopathy.

Can look very wearable. And if you have a horse that gets worse with exercise, that's always something to bear in mind. And don't always expect the typical tying up sort of presentation.

Horses may also have an exercise intolerance, reluctance to go forward in stiffness and can also have variable lameness here, like it was in this case. Of course, we have a gate asymmetry and we've got a predominant right hand left for lameness, and we also have some radiographic signs of Subtle or mild DSP impingement. But if you have the myopathy, I think it's good to sort of treat that first and, and try and manage this first, with some, some management and diet alterations and assess that further.

There may also be other reasons for the horse's lameness, but, also exertional myopathy can cause variable lameness here. DNA testing and, and muscle biopsies and possible next steps to investigate these, these muscle cases further. Case 4 is a 12 year old mayor used for low-level, competition, and, it was suddenly resisting work under the saddle.

I was nervous when being tacked up. The saddle was recently refitted, according to the owner. And, this is the sort of, video she took, so the horse.

Is being tacked up and as soon as the girth tightens, and the horse starts getting nervous, usually a very relaxed horse stands there, doesn't move. The video is actually longer but I just wanted to show, you know, this sort of behaviour here and it starts sort of being nervous, moving around, not standing still, swishing the tail and even with the saddle being on for a while and the whole owner moving away from the saddle, stopping to sort of tighten the girth, the mare is still nervous here, moving around. Under the saddle, the signs are subtle, constant fishing with the tail, not wanting to go forward and sort of leaning downwards a little bit, where the sort of complaints by the rider, just a very different feel of the horse at the trot, you can see it's not really truly going through the back here and having not a very nice posion tail swishing.

Constantly and generally, maybe not the happiest horse. And Of course, now there are many, many things that we can do as we've all discussed, but if there is a problem with tacking up, I always think it's really important for us, vets to also check the, the, the tack. And ideally have a saddler that we trust to work with to have an expert opinion, but, also for us to check the saddle and sometimes it's really easy if the saddle sits like that and we can move it around like that.

It's certainly not a good fit. Really, really important is to look at the saddle without any cloths or anything, just like that, and maybe even put the, a girth on, and you can see it's sort of not even touching the horse's back here, on, on the side, and it's very clear that this is a very poorly fitted saddle. And, this is common.

Poor saddle fit is common. And according to a study from the Animal Healthris from 2015, they found that more than 30% of the horses with saddle fit checks, at least once a year, had ill-fitted saddle saddles. Yeah.

So, poor saddle fit is, is a very common problem and also certainly a common cause of, of back pain. And If there is as much as there are other causes for being girthiness and so on, but if, if there is a problem when the horse sees the saddle, I think we should zoom into the saddle as well and check that out. And often enough, we will find the problem there.

Case 5 is a horse with a, a history of insidious onset of performance and unwanted ridden behaviours. This is how it looked like. So the owner actually for months now, got worse and worse, and now she can't even get the horse into trot and shows tail swing and kicking out as soon as she asked the horse, to trot.

And we have a back x-ray here that shows a very, very subtle, bony reaction and a slight narrowing of the, interspinous space. So very. Something that, you know, probably we would maybe be inclined to sort of overlook, but clinically, it's, it's all made the impression that the source does have a back problem.

So if you would block a reduced space like this, you might Just get a response like that. So, now, the, the owner, is, is trotting the horse, and I think she's even encountering it. What is really a nice luxury to have is if you have a second rider to, to test, so especially if you have maybe an inexperienced owner, to get an experienced rider.

On board and ride it before and after your blocks is good as well. Just to see whether it's a potential rider horse relationship problem. And, it's nice to see that both riders have the same improvement, or the same after the block or the same problem before the block.

So, so, this horse here, trotting and cantering much, much better now. So we have to establish the clinical significance of imaging findings, using diagnostic local anaesthesia where possible, of course, considering our safety aspect. And yes, the severity of the pathology can sometimes be misleading, yeah, so we had an example of a very severe kissing spine case where it wasn't the case, and we have a case of a very subtle DSP, and it, it was the problem.

So as much as commonly things correlate, they don't often, and if we don't, if, if we get tangled up in the complexity of the case, maybe going back and and checking out the, the, the, the findings again does make sense. This was a young inventor, that always worked well and fine, and then suddenly it started from one day to another, to be reluctant to move on the right. And that got worse the more the rider used the leg on the.

Right side. So, it goes on the ride, the rider tries to sort of bring the leg and the horse kicks out at the leg 8, gets more and more nervous, and the situation getting always worse. So rather than working the horse through.

the voice showed signs, like bucking or even not even wanting to go into the trot again, like you can see here. This horse had cintigraphy and what we found was a, fracture of the rib just in the area where the leg goes onto. Ribs, sometimes, I, I don't think it's a very common cause of Showing problems that may, may mimic back pain, but always something to consider.

And cintigraphy is certainly something that, in my experience, really helps to assess that further. Sometimes the problem we have with ribs is that they, heal as a fibrous union, so this is an ultrasound image and you can see a clear gap here, which is really nice and round, and this is, . A postmortem repair that had a fracture which healed in exactly that way and these might sit there and might be really quiet, whereas others, you know, might be an acute onset and a recent fracture, so stigraphy can certainly help establish those.

The last case I want to show is this was that showed some Bucking behaviour, especially in cancer. Again, a suspected back case, or even a psychc kind of problems. The canter quality was poor, and under the saddle repeatedly every time asked the horse to canter, it would buck and sort of struggle to maintain the gait.

And this problem was solved also by blocking, but not the back of the sacroiliac region. But the Deep branch of the lateral plain nerve. So 10 minutes after blocking both proximal suspensory ligaments, the horse called cancer.

So a nice variety of forces that show that were presented for perceived back pain, that had a variety of either back problems or other orthopaedic issues that are, that are potentially making these problems. So to summarise, there are a number of conditions causing a mimicking back pain. We should stay open-minded when approaching horses like that, presenting with suspected back pain.

We should never overlook lameness and back pain and lameness are frequently linked. We should perform written assessments where possible, and, a lot of the times, if we follow a systematic approach of the workup, we will, reach a diagnosis. OK, thank you very much for listening.

And that's the end of my talk.