Hi, my name is Rachel Tucker. I'm a surgeon at Lippek Ecorn Hospital in Lippek, Hampshire, and I'm going to discuss with you in this lecture, advances that are being made, in the investigation and treatment of neck pain in the horse. This is a topic that I have become particularly interested in through our, ability to CT the necks of horses here at Licor Hospital.
This, imaging modality has really opened my eyes to the things that can happen and are going on in horses' necks. It's really, opening up our understanding, greatly and is also posing us lots of questions that we don't yet know the answer to. So the condition of neck pain in the horse.
In this talk, I'm going to discuss relevant anatomy of the cervical spine. We'll discuss clinical signs, presenting signs and the clinical examination of horses neck. We'll talk through the different options for diagnostic imaging and diagnosis of neck conditions.
We'll then go on to discuss . Pathologic conditions of the horse's neck and I'll use a few imaging examples to highlight some of these conditions. And then finally we'll talk through a range of treatment options, pros and cons, at the end.
So the horse's neck. Is highly adapted. It's got to Achieve a lot of functions in the horse.
Obviously, a prey animal needs to have its head down to graze, but also needs to be able to look up and look around it easily, scan the horizon, keep itself out of trouble. We clearly also ask quite a different set of challenges of a horse's neck, and this image on the right is clearly a very extreme example. This is not normal for for any written horse, generally speaking.
But it just highlights really the difference between the straight neck grazing animal, and, an example of of what we might be asking those horses to do. Looking at the anatomy of the neck, should hopefully, be aware that there are 7, vertebra in the neck of all horses. Sorry, we've got one missing on this, slide.
C1 and C2, the atlas and axis, are highly modified, compared to the other cervical vertebra to support the head and to enable a large range of movements. The joint between the occiputs of the skull and C1 is responsible for a majority of the dorsoventral. Movement of the neck and can flex 86 degree range of movement, which is far greater than the more cordal vertebrae in the neck.
Going down, C3 to C5 are described as typical cervical vertebrae. They are all, all three very much the same. The C6 vertebra has a slightly shorter vertebral body and Can be identified through the fact that it has additional ventral lamini projections of bone of the ventral surface of the vertebral body, which is an anchoring point for stabilising muscles of the neck.
T7 is much shorter and has a small spinous process and no transverse for. So looking in a bit more detail at these vertebrae. This is, A cervical vertebra in transverse sections are looking and on.
Essentially, and this is helpful for looking at radiographs in particular. . The vertebra is a cylindrical piece of bone, the the vertebral body, which articulates with a cranial and caudal vertebra, .
Via, A joint which contains a disc. And then the spinal cord runs dorsal to this vertebral body surrounded by, this neural arch. It's described as, so essentially a, a bony tube, to protect that, spinal cord.
Successive vertebrae joined together, create the spinal canal. And then spanning from, these two structures are bony projections, essentially, which the site of attachment of ligaments and muscles. So cervical vertebrae have transverse processes, very small dorsal spinous processes.
They don't have a huge function as compared to the thoracic spine, and then a ventral crest. In addition, to, the vertebral body articulations, there are also, articular process joints. Which, are very, relevant for clinical conditions of neck pain.
As I mentioned previously, the C6 vertebra is slightly adapted in that it has these ventral lamina, . Which have quite large cranial and cordial tubercles, is the attachment of the longest collie muscle, which is the ventral neck stabilising muscle and, which also causes neck flexion. So these articular process joints sit one on either side of the vertebrae.
They are smooth cartilage covered oval joints, which have synovial joint capsule and contain synovial fluid. They have a relatively large range of motion. They're very mobile, particularly, laterally and to some degree, so particularly dorsoventrally and to some degree laterally in the mid neck.
Their volume has been shown to be approximately 3 mil, but they can be distended much more than that, . And sinusitis and joint inflammation, increased joint fluid can. Can increase the size of these joints significantly.
Importantly, also to know is that. There's a notch that sits just below these articular processes through which exits the . Segmental spinal nerves, .
Between each vertebra. This is a pathological section just showing the articular surface. This car surface and the smooth oval shape of these articular process joints.
So clinical signs of neck pain. Now this talk, I'm primarily discussing only neck pain in the horse. Clearly, another important clinical sign of neck conditions in the horse is after ataxia, and due to cervical spinal cord compression, causing upper motor neuron issues in hind limbs and also potentially the forelimbs.
I think Johnny Anderson has spoken before on webinar that and that there's other things available, so I'm really focusing on the condition of neck pain in this lecture. And that presents primarily, to me, usually as a subtle condition, but it also may be seen as a more acute, more severe finding. So you may be called because our horses found in the stable or found in the field with seemingly low fixed head carriage, unwilling or unable, seemingly to to move their neck, particularly or lift their head up.
They may be having difficulty eating. Getting into a hay net or even getting down to the ground. And they just seem sort of locked and unhappy and, and, generally so.
Differentials for this. There are other differentials, . A recent intramuscular injection in the neck, for example, an abscessation or sauna secondary to to a vaccine.
Those things will need to be taken into consideration in in these examples. But otherwise, you might be asked to look at a horse that just has reduced performance. They might have changed in their behaviour, become grumpy and willing to work, less less willing to work on the bit, for example.
I've had owners report that horses. They just don't seem as happy or as confident jumping their horses, they feel they describe them as feeling restricted or restricted over fences or spread fences, . So these aren't automatically always, don't turn you in immediately on a condition of the neck, but it's an often, a similar set of findings when we look back at our neck cases.
These are often a collection of signs that that we see. We also see recognised horses that can have fallen gait deficits, whether that's a slightly shortened fallen stride orc. Stride, perhaps a hopping type lameness as characterised by Sue Dyson in a in a case series a few years ago.
We also see horses that are tripping or stumbling, seemingly completely out of the blue, often, not just lazy horses, not paying attention to their feet. So all of these horses warrant a careful clinical examination. Now things may seem obvious if you've got an acute case and they just can't move their neck or they've got a a real obvious focal region of pain.
But, but often the more . Need quite a careful clinical exam. And this is an area that I'm always feel like I'm trying to improve my skills up because I think in many cases it can be quite difficult to get a good neck exam in in horses, particularly if they're a bit spooky or distracted or in an unfamiliar environment like we have here often.
When they come into the hospital. So it's important just to take a step back, like in many cases, assess their behaviour, how they're responding to their environment, what posture they choose to take when they're they're left at rest, and whether they prefer to stand with one leg in front of the other, whether they adopt a normal neck position, whether they seem to be stretching it forward or holding their head a little low. palpation is also important.
Looking for any asymmetry or an abnormality in muscling. There may be muscle loss or wastage atrophy. There may be pain, particularly of the brachiocephalicus, and neck muscles, .
You may see hypertrophy. It's not something I've don't recognise there may be asymmetry. You might be able to simply feel the transverse processes, .
Signified in these locations on this image, you may be able to feel them more readily, you may be able to feel the articular processes more readily, indicating muscle loss in in some regions. So palpate carefully along, feeling for the, the bony structures, muscular structures, and looking, for pain, or asymmetry primarily. Range of motion is an important thing to assess, but in some cases this can be a little tricky.
I would definitely recommend standing a horse against a barrier of some sort of fence or wall or having them in the stable, so that if you ask them to move their neck, they don't cheat by swinging their bum or moving their their legs. And then you should do your best to assess the horse's range of motion through a lateral movements, flexion, and also extension as far as you can. So I'll often, take some pony nuts or a carrot and just ask the horse to bend their nose from side to side, and they should be able to quite easily and smoothly without lunging or sort of jerking their neck.
They should be able to move their chin around to the girth on each side, around to their, hips on each side and around to both tarsa as well. And ideally without trying to sort of cheat by rotating, through C1, C2, and, and just sort of lunging, you, you can get a feel about whether there's quite a smooth, movement of their neck and quite even movement through their neck, or whether they're, they're essentially keeping their neck straight, but just twisting and flexing, at the atlas and axis. So I I think that range of movement through sort of C3, 45, actually isn't .
That's great. Most of their movement comes at the the front and the back of the neck, but, but occasionally you do see really sort of boarded regions of the neck, which may well be abnormal. They should also be able to stretch their nose forwards and up for a treat and then down between the knees and their fetlocks, without any difficulty.
Then follows gait assessments, and these horses need to be assessed for lameness, a neurological exam, ideally as well, and, just neck position and posture as well. Some horses will really hold their head to the outside of the circle on the lunge, or they'll have a very low neck carriage, or they'll sort of throw their head around if they're asked to, . Pups when ridden or or with side reins, they just don't like .
Being asked to put their necks in certain positions. So this, you know, to do thoroughly, just needs a little bit of of time taken just to work through all of these steps. So next steps, cervical imaging.
So we'll talk now about radiography, sintigraphy, ultrasound, computed tomography, and also, where myelography, can be of use. So a radiography X-ray is our mainstay option really for imaging the horse's neck. It's been around for for a long time and it's very, very useful, but, .
Really needs to be done carefully and well and takes a bit of practise to get nice, neck x-rays in the horse. It allows assessments of bony abnormalities, and you can get an idea of some soft tissue, concerns as well by by looking at, for any signs of stenosis of the vertebral canal, which might indicate spinal cord compression. The lateral radiographs are are routinely taken.
But the bleak views are also very useful, to remove some of that, superimposition of these large 3D vertebrae. Particularly useful because dorsoventral views are, are rarely obtained. You know, certainly you can't get DV views of the majority of the horse's neck.
They're just too much tissue and it's just logistically not very easy. But, in some instances it is possible to get DV views of of the pole and, and most cranial spine. And occasionally in folds, particularly useful, in cases of suspect fracture in that region.
I couldn't find it, but I've got a lovely . DV radiograph of a C2 transverse process fracture, which was taken in the field and sent to me for review and you couldn't see that fracture on any of the other images. So it was a real key well it was a diagnostic, the diagnostic step in that case was the fact that the vet had thought to take that, slightly unconventional image was really worthwhile.
There's something to think about in certain cases. So I just pulled up a set of lateral radiographs taken here recently. There would also be a pole shot which I've just missed off.
In, in this case. So tips for taking lateral radiographs of the cervical spine, I think, it is very much easier to get good laterals in a clinic environment. So it's all possible have the horse come in.
But if you're in the field, particularly. Certainly make sure that the horses stood on flat level ground, it's nicely sedated with their heads supported on a headstand or something else steady, and that the handler is stood directly in front of the head of the horse so that they can hold their head straight and they can look down the horse's neck and make sure that everything's straight. The horses stood square, the neck straight, the head straight, which then means that you can, direct your X-ray beam.
perpendicular to the, to the floor, essentially, to get your lateral views. Signs of a good lateral are, basically when the transverse processes, completely align with each other, that tells you that there's no obliquity in any direction, so very slight obliquity in in this image. looking at, at these transverse processes, but, but these ones are nice.
And that highlights that, a divergence of the X-ray beam means that often, only a portion of your radiograph will be true lateral and often the periphery you you start to lose that that true lateral view. Another clue is when the articular processes line . Superimposed over each other.
And nicely, which leaves you this air space of the intervertebral foramen. if that's obliterated, it could mean that there's enlargement of the articular process, obstructing this view, or it could mean that there's some rotation of the image. So here we've got C2, C3.
And, C3 to C4, C4 vertebra, C5, so these three vertebrae all look identical to each other. Also worth highlighting that that sometimes it's helpful to put markers on the horse's neck, particularly with portable X-ray machines that have a small, plate, detector, it, it can be easy just to miss little bits of your, sequence of neck x-rays, and they're quite hard to use some of these small plates, just to make sure you haven't missed anything. And down the neck.
we have C5, C6, articulating with C7, which corresponds with C7 here. And then right at the base of the neck, we're looking at the C7 T1 articulation and T1 has a spinous process here. You may see a small spinous process also on C7, and that would be a normal variation.
. Yeah. So oblique projections, if you're able to take them, are particularly useful for imaging the articular processes because it separates the articular processes and allows you to look at them from different orientation. These images are taken from a paper .
A good review paper written by Dema Paowski in EBJ, which just compares a radiograph with a specimen, and shows that, . These views which are taken from a a a ventro, . Lateral to dorsal lateral projection angled at 45 degrees.
Through a majority of the neck, although once you get to the base of the neck, you need to angle your your X-ray beam, a little more to 55 degrees, to get through sort of C56, 67 region. And And tip I guess would be to focus your, your beam approximately 15 centimetres on the neck, 15 centimetres below, the position of the vertebrae, at that 45 degree angle, place your plate perpendicular to your X-ray beam as close to the neck as you can, so you end up moving it away a little bit. And, ideally you'll take, ventral to dorsal laterals on both sides of the neck to highlight, .
The, both sides of the articular processes in the same way. And this allows you then to look through the joint spaces of the near, articular process joint. We're essentially looking down this, this gap, which means that you can look at the, get a nice look at the articular margins and get a bit of an idea of the size of these articular process joints.
And then it also highlights the far articular process joint, dorsally on the image. So again, you get a nice look at the shape and size, and remodelling. There.
So it's a useful image if you're able to obtain it. Just a couple of example images here, key points really for assessing radiographs of the cervical spine. I'm often particularly interested in the articular process joints in cases of neck pain.
So I'm looking at the size, their margination, . Whether they're they're large. If they're enlarged, you can see a loss.
This is a radiograph on my neck of a horse with quite marked changes. So there's a loss of this in this sort of dark, gas into vertebral foramen of both of these sites, . In the base of this horse's neck.
There's clearly, remodelling a new bone, potentially a fragment of bone, sitting up here, . On these lateral views. And then on the bleak views you can look at the joint spaces to a degree, to assess whether they're narrowed, wide, and irregular, at all in their outline.
So quite a lot going on in in these articular processes. We'll also be looking generally for any other abnormalities, developmental abnormalities, signs of fracture, callous formation, changes in relationships between the vertebrae, looking for any signs of cord compression, . He's a little off topic, I suppose, of this talk, but you're still going to be looking for any signs of cord compression, or developmental orthopaedic disease, for example, coral epiphyseal flare, the growth plates of the vertebral bodies, particularly in younger horses, extension of the dorsal lamina.
And you can take your measurements if you if you need as well to look at sagittal ratios that might indicate core compression in some cases. So X-ray is is very useful and very worthwhile doing and worth taking care to get us as good a lateral views as you can. To help you in that interpretation.
Moving on sintigraphy, this is something that's used quite widely as a more general imaging modality generally for for investigation of of poor performance or non-specific issues. It's not used so often when we already strongly suspect a neck issue a neck complaints, unless we're looking more broadly for other findings at the same time, because it is a little nonspecific and And considered to be fairly incentive for for the cervical spine. I think it is useful, for sure, for looking at both articular process enlargement and increased radiopharmaceutical uptake in active and pathologic and articular processes.
This is the example images of a horse that had marked arthropathy. You can see, on this right image, C4 5 and to a degree 56 articulations are, are big, and this one's certainly big and hot, and it's important to take left and right lateral images of these cases. And this also, we'll have a look at him again in a moment.
Ultrasound. Now, I need to use ultrasound more. I think it's something that I, I always mean to to get out more regularly to look at the cervical spine in horses.
We use it very frequently in necks to guide injection of the articular process joints, but it's certainly reported to be useful for assessing some of the soft tissue. Structures of the articular process joint, so the, the joint capsule to look thickening of the joint capsule, should be 1 millimetre thick or so, but it is reported to be up to 10 millimetres thick in some some cases with presumably long-standing sinusitis. So joint capsule thickening, it's possible to look at the joint margins for remodelling, enlargements.
This image below is a picture of an articular process joined to a horse that had a fragment, a fractured fragment. At the margin of the joint, which can be seen here. It's not a smooth white curve of the, of the oval shape of the, joint, but certainly fragmented.
Articular margin. That wouldn't for me be enough. I don't think I'd hang my hat on that as a diagnosis just by looking at ultrasound, but in conjunction with X-ray it can really support a diagnosis.
just also not forgetting that the neal ligament and neal bursa can be a source of neck pain in horses, and ultrasound can be useful there, to look at that bursa for fusion, synovial hypertrophy, and to look at the mal ligaments and the occipital crest for, enthusiast change. So CT computed tomography, and this is we're very lucky to be able to, to image horses using CT, and, CT scanner has been in use here for 5 years or so now. We've imaged about 70, horses' necks through the scanner under general anaesthesia.
. All horses will have plain imaging of their cervical spine and head and a reasonable number will also have positive contrast myelography performed at the same time. We have a wide bore gantry, a bariatric scanner, the 80 centimetre bore, which means that we are able to image the entire c cervical spine of the vast majority of horses. I've heard it reported and discussed that that it's just not possible to CT the whole neck, but, but it really is.
And we have only had one or two horses really in recent years that we haven't managed to to image all the way to the start of the T1 vertebra. So this is the setup. This is a, a 600 kg or so, 5 year old warm blood, that we imaged fairly recently.
So looking from from each end through the scanner. And just highlighting that we are a little bit of healthy shoving, we can, we can get these horses image right up, and get the the cranial edge of their scapula right up into the into the machine, to image. The whole neck.
CT takes, doesn't take very long at all. A plane scan, the horse might only be anaesthetized for for 15 minutes or so, just long enough to hoist them onto the bed, takes only a few seconds to, to acquire, the CT, we then reposition and take their head for completeness, and then, place them back in the recovery box. Myelography is .
It's useful. We'll come on to that in a moment. So CT it's 3D multiplanar reconstruction, removes all of the issues of superimposition, you know, looking at these 3D vertebrae via 2D X-rays.
This hasn't come out that well actually, but it just shows us sort of Non-standard view of a horse's neck and taken in this way to highlight these loose bodies, bone density bodies, spherical bodies that are sitting at the margin of this articular process joint. So it just allows us to manipulate images in a way, to, to get a much better look at these joints, and also to, to, reconstruct the images and look through as slices in in any plane that we want. Slight thickness is 1.25 millimetres, so, it allows a lot of detail to be viewed.
There are some limitations of CT, mainly in that, there are soft tissue conditions that it can't tell us too much about, and nerve conditions, neuritis, myositis, early into vertical disc disease, disc changes, and these sorts of conditions, MRI is clearly would be optimal, but that's not something that's in clinical . Clinically available, particularly at the moment. And we can view CT in tissue windows, but we don't get that sort of functional angle that you get from an MRI.
CT myelography is is also transforming our adding a whole new set of information to our to our interpretation of net conditions. . This is a lateral and a transverse image on the same horse showing positive contrast and myelography has been performed.
. So this is sort of analogous to a traditional lateral radiograph that we'd see. This horse certainly at the base of its neck, you wouldn't have any concern over spinal cord compression, but when you look in cross section here at this level, you can see that there is cord compression laterally caused by degenerative joint disease of this articular process. It's enlarged, there's a large osteophytes here medially, and that is .
Causing a loss of di column and this also was a tactic. So it can be very useful, and it's teaching us more, as we go, with this modality. Occasionally we have the fortune of being able to image one horse in a number of ways.
So this is a horse that was sent in for investigation of poor performance, generally, a few areas of concern, lameness, neck stiffness, and it underwent bone scan, and showed enlargement of C45 and C56 articular processes on the right side. Cradrographs were subsequently taken which showed some abnormality of these articular processes, the suspicion that perhaps of a. Of a fragment or some irregularity here dorsally and and sort of enlargement of the articular process here obscuring some of the invertebral foramen here.
And there was a desire to pursue this, so the horse then had a CT scan. And that reveals clear fragmentation, fragments and smoothly marginated fragments at these process joints. There were two, in, .
The C45 articular process joint and 1 in the 56. These aren't the same fragments exactly in this case, but these are examples of of of some of what these fragments look like. So those rolling around these small joints with 3 millimetres volume, is certainly considered to to to be likely to contribute to neck pain in these cases.
So we've already started to talk about some of the conditions that we're finding in horse's necks that cause pain and in some cases they attack you as well. And we can't entirely separate the two conditions. We're just gonna run through this sort of differential list, the most relevant conditions for neck pain, .
OCD in younger animals, often associated also with ataxia and the traditional warbler, presentation. More importantly, probably the most important is articular process, joint osteoarthritis, degenerative joint disease, which doesn't sit as as its own entity as there can be associated problems, which we will discuss that of cervical nerve root compression, the presence of, of loose bodies or fragments in these joints. And as seen on that CT myelogram, the potential for spinal cord compression too.
Osteomyelitis is a differential, and particularly in younger animals. We've seen, fractures, subluxations, and then there are soft tissue conditions such as mucal ligament issues, mucal bursitis, intervertebral disc disease, neoplasia, all much, much less common, but certainly can occur. And I'll just mention morphologic variations as well.
So APJ osteochondrosis, this is seen, has been described histopathologically in in all from all sorts of sources now, particularly in horses, young horses diagnosed with cervical cord compression with warbler syndrome. It may be represented by, small fissures in the cartilage surface. That's something that's difficult for us to identify, antemortem.
But also we can see larger irregularities, particularly on CT, in the joints, . Including lucies, subchondral cyst-like lesions within the articular processes within the vertebral bodies, often spread throughout the neck, particularly in the cranial cervical spine of younger animals. And these can be associated also with degenerative changes.
And these are two articular processes, one from the left and one from the right side of the neck of a 12 month, yeah, a yearling thoroughbreds, . These lesions were confirmed as OCD, on histopathology, but also you can see that this facet joint, this process joint is much larger than the contralateral side, is irregular in shape, and has this this joint margin lipping as well, which are all signs of degenerative process. So things don't exist in isolation.
There's much more . That can all be going on in combination in these cases. This is an OCD case that we CT scanned a little while ago now.
It's a 6 month stallion that presented with neck pain and ataxia. I think in reality the ataxia was more of a of a relic presenting feature in this youngster, but, just to, to demonstrate really that . Some OCD signs in this course, with fragmentation of the articular processes, or as a, markers of the presence of developmental orthopaedic disease.
So osteoarthritic changes are are very commonly seen, and it's worth noting that enlargement of the APJs of the base of the neck has been recognised in non painful horses, those with with no evidence of neck issues. So to some degree, enlargement may be a normal feature in older horses, so shouldn't be overdiagnosed, particularly on radiography. .
Features that we might see, as I've mentioned, are a joint enlargement as seen here. lipping of the margins, irregularity of the joint space. And this enlargement can cause narrowing of the outflow tract of the spinal nerve.
And this is something that that I'm interested in. I don't think we know enough about what what effect this might be having, having, but you can certainly imagine that neuritis, radiculopathy, nerve root compression, . Could certainly be occurring in these cases.
This is a, a transverse reconstructed CT image of an event horse just 5 years old, presented with neck pain, really grumpy horse, this was, didn't like moving his neck, cantered and trotted on the lunge with the neck head held low, and on closer examination, was, was, grade 1 out of 5, ataxic in the hind limbs. The, these are, the C6, C7 facet joints which are very enlarged. And irregular with markedly narrowed into vertebral foramen to see there.
So these are fairly extreme examples of of osteoarthritis of these facet joints. So looking at this this condition of radiculopathy, it's certainly something that's been been shown very much to occur in man, with neuropathic type pain rather than inflammatory pain. and, analysis of, Nerve samples, work being done at Colorado State, Kevin Hauser and colleagues, they are describing histopathologic findings of, of nerve inflammation.
As you might expect really looking at the CT images, this is a specimen, . And our interns did a nice study looking at these nerves, and the transverse process has been removed of this vertebra just to show, number 3 here. This is the spinal nerve exiting from below the articular process joint, in this, .
In this dissection. So something else that we're recognising in conjunction with arthropathy, primarily are these discrete. Loose fragments or or loose bodies where we're describing them as, because we're not entirely sure that they're fragments.
They rarely have clear, fragment bed location that we can tell that they've come from. And in the 1st 55 horses that we, performed an XCT on, 12 had, Had fragments identified on CT. So, so currently we have an incidence of 24% of our CT cases having these fragments identified.
As I mentioned, they are almost invariably associated with OA, but I've also been identified in conjunction with other findings such as. compressive myelopathy, in warbler cases. So it's difficult to specifically say how significant these fragments are to to neck pain, because they are not really found on their own as a as an isolated condition.
But certainly, we don't really know whether it's a, you know, the chicken or the egg. Does the, does the fragment, produce arthritis or does arthritis and fragmentation? This fragmentation hurts secondarily to the arthritis, .
We've presented and published an EBJ article discussing these fragments in more detail. And histopathology suggests that they may. Be more accurately termed as osteochondromas rather than osteochondral fragments.
Histopath has shown that these, fragments, I keep calling them fragments, . Consist often of small core of necrotic bone or cartilage, surrounded by concentric layers of cartilage that presumably have been laid down over time. This can occur through being nourished by the synovium.
So, small fragments can grow within the synovial environment of of sitting in a joint, and can enlarge over time and by looking . And the microscope of these fragments which we have removed to date that suggests that this is the aetiology of of a number of these fragments. These images just show .
Orthogonal views on CT of a fragment, which could also be seen nicely on an oblique radiograph sitting here at the margin of the articular process. This is one that we subsequently operated and performed arthroscopy on the articular process joint, and you can just see some rounds here on this arthroscopic image, reaching to to grab this fragment here, to remove it from the joint. So, a potential and useful new treatment option here, thanks to CT providing us with more detail of these of these fragments, as a number of them are surgically accessible and we are beginning to operate on on very selected cases of these.
Moving on to other less common conditions of the neck causing neck pain. These are images taken from a four month fall which presented with neck pain, stiffness and discomfort on rising generally from sleeping, but also had an intermittent pyrexia. These images taken 10 weeks apart show real obliteration of this end plate of the vertebral bodies here and complete loss of of the disc space and.
This was consistent with the diagnosis of of bacterial osteomyelitis, and after some intensive antimicrobial therapy, this is, where, things ended up. So certainly quite a lot of damage occurred here. We're also seeing some some more puzzling cases.
This is a a radiograph of a Connemara pony that had quite a long history of poor performance, not quite right, didn't really jump as well as he used to, . But we ultimately imaged him because of sudden onset, reasonably severe ataxia. On this radiograph, you can see that the dorsal lamina of the spinal cord is very irregular and you can sort of follow it along, here, here, and then there's a big step.
And there appears to be some bony protrusion into the spinal canal, which is widened at this location and narrow here. It's a little bit of an odd picture really. We didn't quite know what to make of it.
We were lucky enough to be able to CT this pony. And this shows, . A really an unusual picture, but clear, cord compression and loss of the dorsal myelographic dye column here, .
It's quite hard to know exactly what this, this is a a chronic injury of some sort, we suspect, compressive injury, somehow the dorsal lamina. Of C6 is overriding the cranial dorsal lamina of C7. And I think we're never quite gonna know the the exact process of this horse.
But at the time of CT imaging, there was no palpable, . Abnormality in this area, the horse had a pretty good range of movement of his neck, . .
Yeah, there were no signs of acute injury, particularly. A quick mention of a morphologic variation at the base of the neck, because there's some debate as to whether this is a source of neck pain in horses. So there's there's many papers, X-ray based papers out there discussing the normal variation of C6, C71 in horses.
This is one of the more common findings in that . This is a transversity of C6 vertebra. This is C7.
You can see in the C6, that's the ventral tubercle on this left side is absent, as is . The, vertebral foramen here, which carries the vertebral artery in vein. And then you move back to C7 and you see that it's appeared, it's here, and it shouldn't shouldn't normally be here.
And this is a finding reported in somewhere between 10 and 30% of horses. There are people who strongly believe that it has no effect on the function of the horse's neck, but others that suspect that asymmetry of the attachment of longest poly muscle to to this . Tubercle, can, be a source of pain or poor performance.
One study of 100 horses, those found to have this neck morphology did have a higher likelihood of neck pain and warm bloods were overrepresented. My experience to date, I'm not sure what I think. I've seen some horses with subtle and, neck issues that have had this condition, but also many that, .
. Also with neck pain that don't, so I think it's very hard hard to call. Soft tissue conditions, all rare, and in some cases, difficult to diagnose, can play a role, we think in neck pain and are probably overlooked because they're difficult to diagnose.
So, muscle muscular issues, ligamentous issues, and this is a nice example. These images are taken from a paper by Helier out from that radiology and ultrasound showing ligamentum flavour enlargement. As a cause of well, in this case it was ataxia, but just an example of soft tissue structures that we might overlook that can cause conditions of the neck.
Sinnoitis is likely to be pathological and any any time that we recognise it, whether that's on CT or on ultrasound. But again, I think, potentially overlooked, and CT myeography, and ultrasound can help us here, if we, if we use them. A few other, again, rare conditions that I won't dwell on too much at this stage.
Moving on to treatment. Now, it's all very well us having these new insights into all sorts of pathologies of the neck, but I think it's fair to say that we're still relatively limited in the options that we have usefully to treat these neck conditions, given that in most cases away is a factor and that's something that we struggle to to to treat in any location in in our animal patients. So in some cases, rest is indicated, particularly those more acute painful, .
Next, oral analgesia certainly plays a role, but I'll come on to why it may not be as effective as we hope it might be. I'll discuss some other systemic medications, joint injections, the option potentially for for nerve outflow track medication, discuss briefly some physical therapies and also surgical options. So conservative management of neck pain, vast majority of cases, as I mentioned, rest is important or, or at least limiting those movements that are particularly painful, certainly until some treatment's been instigated.
Oral NSAIDs are mainstay, pain relief, anti-inflammatories, such as the albutasone or, sibuzone Daolon. Although there is some discussion that neck pain cases, particularly those which are likely to have a component of nerve compression, these cases they have a component of neuropathic pain rather than primarily just inflammatory pain and sinusitis. And so.
We know that neuropathic pain does not respond so well to these non-steroidal anti-inflammatory drugs. And, and therefore, It's certainly an area that we we don't yet know enough about, but it may be that oral non-steroidal drugs don't necessarily have the same effect as they might do in joint pain in in other locations in the horse. Gabapentin, therefore, becomes a sensible, theoretically a sensible option for for managing that neuropathic pain, and regulates calcium channels and so works on on nerves directly.
However, it's a little bit expensive and also very disappointingly, the bioavailability of the oral gabapentin is, is very poor. At 20 megs per gig it's been shown to have a bioavailability of 16%, which means that in the vast majority of cases are unlikely to reach therapeutic levels. Now bioavailability varies greatly between horses and and different situations, so it may work in some cases, .
But it also may, may not, or cost may prevent its long term use. Sic steroids may have a role, particularly in the acute cases. I'd often given an acutely painful horse .
Dexamethasone is a sort of more potent anti-inflammatory, but it's rarely a useful medication as a normal long-term drug in horses due to the potential for side effects. Bisphosphonates have been discussed as having a role in managing bone-related cervical pain. There's one study that reported bisphosphonates for children to improve the flexibility, mobility in the thoracol lumbar region of horses with suspected facet osteoarthritis, in the thoracol lumbar region.
That's really all we have in the literature as far as I'm aware. It's not something that I, would currently use, but perhaps something to, to consider. Intra-articular injection really is, is, mainstay treatment, I think, for management of neck pain associated with, articular process abnormalities.
So the, the arthropathy type cases. This image just shows me medicating . The left articular process joint of this horse towards the base of the neck, under direct ultrasound guidance.
I've got the the curvilinear ultrasound probe with a sterile glove over it in my, in my left hand. To take the image that you can just about see on the screen there, the, needle, . I don't know if you can quite see it's coming in from the, the top left of the screen and going into that joint space there of the curve of this articular process, and satisfyingly there's some synovial fluid in the hub of my spinal needle, so I know that I'm in the joint there, .
Would you triamcinolone as a I mean stay Steroid here, these are relatively high motion joints and and certainly trainone is going to spare the cartilage better than. Depomedrone, you start prednisolone, well, with that generally recognised a total body dose of 18 milligrammes, . Used pretty much, pretty consistently with medicate, articular process joints bilaterally.
It's quite rare to, well, it's quite rare to be very confident of your diagnosis of a lesion being unilateral, unless you have the benefit of CT of course. And there's some good papers here to to discuss the technique for facet joint injection, if required. Physical therapy is very little evidence as to what effect various physical therapies have in the management of these neck conditions.
Physiotherapy, may play a useful role for soft tissue management of soft tissue, . Injuries or muscular tension associated with deeper joint pain, of course, you need to be fairly sure of your diagnosis before you start manipulating a horse's neck in case there is a fracture or something that would certainly contraindicate any sort of manipulative therapy. Often horses will have some sort of therapeutic exercise programme, whether that's carrot stretch type exercises or ridden exercises with the aim of mobilising joints and activating or strengthening the hyaxial and hypoxic musculature.
Well I've not found any really good evidence of exactly what exercises. And achieve what goals, and this is still very much an empirical and used method. But at least it's controlled by the horse.
So, they're not going to electively put their neck in any position that is out of out of their comfort zone, if you like, which may be a good or bad thing depending on what you're trying to achieve. Acupuncture may certainly play a role in providing analgesia for, for neck conditions. These are the sort of adjunctive therapies that are used in man, for cases that are have neuropathic components or less inflammatory conditions.
. Tends transcutaneous nerve stimulation has been shown to modulate pain, and, but there's no research to support it or, or otherwise in horses. Extracorporeal shock wave therapy has been described certainly to treat mucral ligament asmopathy. It's Has a role as analgesia and stimulating healing, particularly of a ligament insertional injuries, and, has been shown more generally to reduce pain and increase range of movement in humans with cervical pain.
But there's again, I know that anecdotally that it's it's been used to manage neck pain in horses at other sites of the neck. I have little experience of its use myself, and I've been unable to find any literature again to support it or otherwise. Perineural injection is a new sort of discussed option, that's been reported very recently by Andrew Wood and out of out of lip book and Cruz Sanabria in another paper, both published in 2021.
. Both of these papers are looking at the technique of perineural injection of the cervical nerves in cadavers, and there are no published reports of their use in clinical cases. We have injected a small number of horses with anecdotally good results so far, but this is early, early days. I, finally, just to, mention, the surgical options that exist for managing neck pain in horses.
Essentially that boils down to two options at this moment in time. There's a slowly increasing amount of literature looking at arthroscopic evaluation of the articular process joints. This paper has very recently been published in vet surgery, and we have this paper reports 3 cases whereby Horses have had fragments arthroscopically removed from their articular process joints.
We have another small case series of 5 horses where we've removed fragments, going through the review process at the moment. This is a technically challenging surgery, but certainly, in this total of 8 cases, 7 horses with the presenting signs of neck pain without ataxia have shown significant improvements in their . Presenting signs.
So it does appear that these fragments are clinically relevant and that certain, in certain cases, fragments can be removed with, with good results. The one course of those cases that has not done so well had marked arthropathy at other sites and and also low grade ataxia. Improvement was noted, but not resolution.
Just a few arthroscopy images, showing the inside of a synovial synovial articular process joints, including images of of fragments inside here and taken from that that surgery paper that's just on LED. And these are examples of some fragments that we've removed from these articular process joints. Very finally, cervical vertebral stabilisation, or lobular surgery, is traditionally, described as a, as a treatment to stabilise the spine and and cervical spine and reduce ataxia in horses, but it does have a role in managing arthropathy as well.
It's been shown that articular process joints reduce in size at a year post warbler surgery. I guess as, you know, Wolf's law, and these bones are no longer in use and, and, and shrink, essentially. So, there is a role that, this surgery could play in the management of neck pain, cases without ataxia, but I think it's fair to say that that is very rarely performed, currently.
Partly, I suspect because it is such a, a technically demanding, expensive, and, a surgery carries certainly reasonable amount of risk, to the horse, along with it. My last slide here just really a couple of final thoughts to summarise what I've just been speaking through for the last hour or so. I think that diagnosing and treating neck pain in horses can be challenging, particularly as many of these horses can have quite vague initial presenting signs.
So diagnosis and investigation needs to be thorough and quite detailed, . There are a range of diagnostic imaging options that can be very useful in evaluating the neck, but, their, their value can certainly be maximised by obtaining the best quality images possible, and particularly good lateral radiographs. And Where possible, advanced imaging can add a huge amount to the understanding of and the diagnosis of these net conditions.
And, advanced imaging is becoming more widely available throughout the UK and and. Elsewhere, and, where possible, they can certainly be utilised to good effect. Obviously accepting that, there are costs and in some instances, a small amount of risk included in that process.
I think certainly our mainstay treatments of facet joint disease is intra-articular medication facet joints, with some practise and and under ultrasound guidance, and they are very readily performed these injections, and, and can be hugely effective, certainly, very regularly have great feedback, good response, and horses returning to a good function for a reasonable length of time following . Corticosteroid joint injection. It's worth remembering that surgical options do exist, so not something to be completely discounted in selected cases.
And finally, I think there's an awful lot that we still need to learn about the horse's neck, the underlying disease process is, what's driving these conditions, why young horses can have such marked arthropathy, and what effects that . Neuropathic pain has on these conditions, where there's radiculopathy, fits in, in, in the, the, the wider picture. And also where the soft tissues overlying these, vertebraph play a role.
Myofascial dysfunction is, is a topic of discussion in some fields. So that's my, speedy run through, . Thank you all very much for listening.
I hope that's been some use to you all. Thank you.
