Assessing some accessible parameters like the colour of the mucus membranes or the paw pads, auscultating the thorax, palpating the peripheral pulses, checking the temperature may help us suspect some of these conditions.
A crucial part of the hands-off neurological examination, especially when we talk about spinal diseases, is the assessment of the gait. In neurology cases, there are two essential things of the gait that we should assess.
One is the VMF (voluntary motor function) or movement, and the other is coordination. Not very frequently, but in some cases, some neurological disorders may display lameness as well.
So, if we talk about VMF and have a decreased VMF, we say that this animal is paretic, or we have paresis. A paretic animal can still be able to walk, in which case we will have ambulatory paresis. When there is no VMF, we talk about plegia or paralysis.
And when we have plegic animals, we should assess pain perception or nociception, so the ability to feel pain, with a forceps squeezing toes, for example.
Hence why we only assess nociception in spinal disorders when we have animals with plegic limbs. If we have paresis, we should not check nociception.
Talking about coordination, especially when there is a big crisis among the coordination,
we say that this dog/cat is ataxic. And then use the prefixes mono, Hemi, para and tetra to say which limbs are affected. If they have ataxia, most spinal diseases will be proprioceptive ataxia, but as you know, there are other two types of ataxia: cerebella ataxia and vestibular ataxia.
As said before and this is not a typical case of foraminal disc extrusion, discospondylitis, or Degenerative lumbosacral stenosis may present with lameness generally as a result of nerve root signature, but this is not common.
Getting into more detail, if we talk about neurological examination, it is essential to differentiate signs of upper motor neuron and lower motor neuron disease. So, talking about anatomy, the upper motor neuron cell bodies are within the brain, and these neurons are responsible for three things:
Initiation of voluntary movement,maintenance of muscle tone for support against gravity the regulation of posture.
This upper motor neuron activates or inhibits the lower motor neuron, which is the neuron in contact with the muscles.
These cell bodies are in the cervical-thoracic and the lumbar intumescences.
Hence, the clinical signs of the neurological dysfunctions that we will have in cases of upper motor neurons will be very different from lower motor neuron cases. Proprioception or postural reactions can be decreased or absent in both instances. Still, as you can see, the spinal reflexes and the muscle tone will be either preserved or increased in cases of upper motor neuron disease, and there will be reduced, absent or highly decreased muscle tone when we have diseases affecting the lower motor neuron system.
If these animals have muscle atrophy with upper motor neuron disease, normally, this atrophy is the result of disuse, so it will be slow and mild. However, if we have a lower motor neuron problem, this muscle atrophy will be neurogenic, and it will be quick and severe.
So, after having done this examination and having deficits in some limbs and depending on the type of deficit that we have, we will be able to tell where the lesion is within the spinal cord, and as we know, we have four spinal segments which are C1-C5, C6-T2, T3- L3, L4-S3.
So when we have a C1-C5 spinal problem, it’s very likely that we have UMN signs in all four limbs. When we have C6 – T2 disease affecting the spinal cord, the deficit in the thoracic limbs will be typical of the LMN, so we may have decreased perception, but we will also have a poor muscle tone, we may have decreased reflexes in the thoracic limbs, but in the pelvic limbs, we will still have a UMN presentation.
With T3-L3 and L4-S3 myelopathy, we will have normal thoracic functions, we will see exceptions in just a few minutes, but in the pelvic limbs, it will depend if it is T3-L3 myelopathy we will have reserved spinal reflexes, or we may have absent proprioception.
However, if we have an L4-S3 spinal cord problem, we will have a poor muscle tone, atrophy, decreased proprioception in the pelvic limbs.
It’s important, especially when we talk about spinal cord diseases and even more so in an emergency setting to grade neurological dysfunctions because it will tell us a lot, as we will see later, about prognosis.
There are different classification systems, but this one is very simple and helpful. We have five grades from the mildest 1 in which we have no neurological dysfunctions, but we only have spinal pain to the most severe one, which is 5 in which we have paraplegia, so inability to move the limbs voluntarily without nociception, without pain perception.
So, when we talk about acute spinal diseases, and this can be an exception to what we have said two slides ago, it is very important to know a syndrome called spinal shock. This is a condition seen in acute and severe thoracolumbar myelopathy.
These patients that normally have T3-L3 myelopathy, if we are correct, should have preserved spinal reflexes in the pelvic limbs because the spinal reflex arc is anatomically spared.
But these dogs may exhibit transient hypo or areflexia caudal to the lesion in T3-L3 myelopathy.
In dogs and cats, spinal shock is genitalia considered to be short lift. However, there’s evidence that pelvic limbs we draw reflexes may be decreased for periods of 12 to 48 hours.
It’s multi associated with chronic myelopathy, so vascular accidents in the spinal cord, but we see as well very frequently an acute disc disease.
Another abnormal and very distinct and characteristic posture is the Schiff-Sherrington posture. We may see this in thoracolumbar or cranial lumbar myelopathies, and this happens to a disruption of the ascending tracks that inhibits the thoracic limbs extensive muscles.
Therefore the result is extensive hypertonia of the thoracic limbs, as you can see in the dash in the picture with paralysis or severe paresis of the pelvic limbs. This is when dogs are in lateral recumbency because when they are healthy in a standing position, there is a normal motor function in the plastic limbs and normal proprioception in the plastic limbs.
Schiff-Sherrington posture is merely an anatomic phenomenon, and there is not we can note anything regarding notice for attempted ambulation, which happens exactly the same with spinal shock. So there is no problem associated with the presence of Schiff-Sherrington or spinal shock. It just suggests severity.
3-LOGICAL CLINICAL REASONING
So, after having done our neurological examination and taken a good clinical history, automatically our differential diagnosis will narrow down. Taking into consideration the most common conditions that we can see in each breed, species and age group, we will also contribute to approach each case accordingly.
It’s very important to remember the temporal behaviour of each aetiology to come up with a differential diagnosis. For example, vascular diseases are peracute in onset, and neurological deficits tend to be quite drastic and dramatic to start with. With time though, these signs tend to stabilise or even improve with no physic treatment, and this is completely different if we compare it with how paraneoplastic or some degenerative diseases behave.
In these cases, clinical signs are likely to be chronic, long-standing and slowly progressive.
5-STEROID-RESPONSIVE MENINGITIS ARTERITIS
So the first disease I am going to talk about is steroid-responsive meningitis arteritis. This is a condition seen in puppies or very young dogs; although it may happen in many breeds, there is a strong breed predilection, with beagles, boxers, and Weimaraners being over-represented.
Since the disease doesn’t affect the spinal cord parenchyma, neurological deficits like paresis or ataxia are not seen. Instead, the most clinical signs are rather systemic.
These include neck pain, lethargy, fever and anorexia. Blood work can increase the suspicion of responsive meningitis arteritis, and we see clinical-pathological signs suggestive of acute inflammation like neutrophilic or even monocytic leukocytosis, hyper global anaemia or hypo albuminia. And the value for the biomarker is the C-reactive protein which is very sensitive but also unspecific, so it can increase in any inflammatory disorder.
6-STEROID-RESPONSIVE MENINGITIS ARTERITIS
For this reason, simple imaging of the spine may help us rule out the causes of severe neck pain and pyrexia, for example, discospondylitis or even atlantoaxial subluxation or fractures.
In order to further support the diagnoses of SRMA, the spinal fluid analysis should be performed and should confirm the presence of pleocytosis with a predominance of neutrophils, as you can see in the right bottom picture.
In warm countries with a prevalence of vector-borne diseases, this should also be ruled out. So, since we are dealing with immune-mediated disease, the cornerstone of the treatment is immune suppression, and this is successfully achieved in most cases with corticosteroids, initially at immunosuppressive doses and then gradually dose decrease should be done upon clinical examination and C- reactive protein monitoring.
Auxiliary immunosuppressive drugs like cyclosporin, azathioprine or cytarabine are not normally required. The prognosis is good in most cases, but we can see relapses, especially if the dose decrease of the Prednisolone is too quick or if the duration of the treatment is too short.
7-INTERVERTEBRAL DISC DISEASE
This is a broad term widely used in veterinary medicine and in composis arrange of lesions affecting the intervertebral disc. The intervertebral disc plays a critical role in the stability of the intervertebral column, effectively binding individual vertebra together to provide support to the entire axial skeleton while allowing multiple nia movements.
There are three main parts: the nucleus pulposus that we can see here, which is a gelatinous bean shape mass that seats slightly dorsally within the intervertebral disc; then we have the transitional zone that represents the transition from the nucleus pulposus to the annulus fibrosus, and finally, the annulus fibrosus which consists of inner and outer regions that are both characterised by concentric fibrocartilage lamella.
The first type of disc disease is intervertebral disc extrusion, or intervertebral disc disease Hansen type 1. This consists of chondroid metaplasia, calcification of the nucleus pulposus, which ultimately results in a type of intervertebral disc herniation whereby a calcified nucleus pulposus acutely extrudes through a ruptured annulus fibrosus into the intervertebral canal, causing spinal cord compression and, in many cases as well contusion.
Chondrodystrophic breeds are more commonly affected, or it may happen with any breed and pretty much at any age. Neurological dysfunctions may be variable from plegia with a stenosis section to spinal pain, and any single spinal cord segment can be affected from the neck to the lumbar area.
Simple radiographs and routine blood tests are unlikely to be relevant in the diagnoses, and in most cases, what we need is advanced imaging like MRI or potentially CT or myelogram.
How can we treat these cases? So we can treat them conservatively or surgically. To treat these cases conservatively, we should do to instigate strict cage rest, potentially up to 8 weeks, because this is the time that annulus fibrosus requires to heal up.
It’s important to provide our patients multimodal analgesia using NSAIDs, potentially gabapentin, paracetamol, opioids for a few days or a combination of them. This will depend on the intensity of the hyperesthesia/pain they may have and potentially as well on the side effect that each individual dog may have on certain medications.
Pharmacological and even manual bladder management is required, especially in non-ambulatory patients. Physiotherapy and hydrotherapy can help as well, especially in cases of severe neurological dysfunctions.
And surgery will boost potentially the best outcome in dogs with a high grade of spinal cord disease, so mainly non-ambulatory dogs or dogs who don’t respond to conservative management.
8-PROGRESSIVE ASCENDING-DESCENDING MYELOMALACIA
When we talk about intervertebral disc extrusion, it is crucial to bear in mind this condition:
progressive ascending-descending myelomalacia. This is an irreversible softening of the spinal cord parenchyma that happens in dogs with severe spinal cord injury, normally in dogs grade five, plegic without nociception. This is irreversible, progressive and catastrophic and life-threatening, requiring euthanasia in the vast majority of the cases.
So, it’s not a common condition, and it only happens in 2% of the whole population of dogs with intervertebral disc extrusion. Clinically these dogs with grade five spinal cord disease develop new deficits of spinal reflexes; for example, in the pelvic limbs on the poenia reflex, we have a cranial travelling of the cutaneous trunci reflex, we may have flaccid abdominal muscles, Horner’s syndrome, even flaccid limbs deficits and specific pain, anorexia, difficulty to keep sternal recumbency and respiratory failure.
So as I said, it is uncommon, only 2% of the whole amount of dogs that will have acute spinal cord compression and disc extrusion; but it may be more likely if we talk of dogs with being great five myelopathy (percentage increases a lot); it is more common when we have a rapid neurological deterioration, having a dog that in just a matter of 12/24 hours period goes from ambulatory to non-ambulatory or even paraplegic.
French Bulldogs seem to be more represented in this disease, and it happens more often when we have mid to caudal lumbar discs compressing the lumbar intumescence.
Normally the onset of clinical signs of this condition of myelomalacia happens in this window of time from 2 to 5 days after the onset of the neurological deficit, although we may have a delayed presentation.
9-INTERVERTEBRAL DISC EXTRUSION . PROGNOSIS
So talking about prognosis and as you remember this grade, we said before 1 to 5, as you can see, the main cut off is feeling pain or not feeling pain. If we have a dog that has nociception, the success rate is as high as 97% or even 93%. However, chances drop significantly by almost 30% when we have dogs that don’t feel or don’t perceive pain.
And why is it very important, especially when we have paraplegic dogs, to assess pain perception?
10-INTERVERTEBRAL DISC PROTRUSION
This consists of five-grade metaplasia of the disc and progressive thickening of the dorsal annulus fibrosus, which ends up protruding dorsally into the vertebral canal; It typically happens in non-chondrodystrophic breeds over the age of 7 years, suggesting that this type of disc degeneration represents a consequence of late-onset age-related changes in comparison to chondrodystrophic dogs.
Considering the age group that we are dealing with, simple imaging may be useful to rule out all differential diagnoses with similar clinical presentations such as spinal neoplasia or osteoarthritis. We are talking about aged dogs, so performing blood- work, urine analysis may be recommended to check for diseases commonly seen in senior dogs like chronic kidney disease, endocrinopathy, systemic hypertension etc.
Normally this dog will have a clinical history, being chronic, slowly progressive and long-standing, although we may have some acute and chronic presentations.
Treatment can be conservative, which will consist of moderate exercise restriction, instigating multimodal analgesia (and this can include NSAIDs, gabapentin, paracetamol and other pain relief). In these cases, a holistic approach may be recommended, and they will definitely benefit, many of them, from physiotherapy and hydrotherapy and potentially other alternative approaches.
Surgical treatment is an option in dogs with a high grade of myelopathy, so basically non-ambulatory or severely paraparesis dogs. In cases when conservative management fails, we need to be aware that the goal of spinal surgery in cases of chronic disc protrusion must be different to start with to cases of acute disc protrusion because sometimes a full recovery may not be achieved, and it is common to see a temporary post-operatory neurological deterioration in these cases.
11-ACUTE NON-COMPRESSIVE NUCLEUS PULPOSUS EXTRUSION
This is an extrusion of healthy and dehydrated nucleus pulposus material through the annulus fibrosus, which erupted and caused spinal cord contusion with minimal or no spinal cord compression. Since the disc material does not degenerate, this condition is more common in non-chondrodystrophic breeds. Cats may also be affected by this disease with the same clinical presentation.
The clinical presentation is basically peracute onset of signs of spinal cord disease. Normally it is associated with vigorous exercise and trauma. We normally see often high grades, so in dogs with severe, para, mono or tetraparesis, it tends not to be painful after 2 or 3 days or beyond the clinical signs, and many times, the neurological deficit will be asymmetric.
Although a presumed diagnosis is achieved with advanced imaging, MRI, simple imaging like radiographs will help rule out causes of traumatic spinal injury, like fractures. And this is particularly important because, as we have just highlighted, the onset is normally linked with trauma.
It is important, when possible, to achieve a diagnosis because the type of management may be different from other causes of acute spinal cord injury, like vascular events that we will see shortly. So in cases of acute non-compressive nucleus pulposus extrusion, rest is essential because the annulus fibrosus, as I said, is ruptured; such an intense physio or hydrotherapy may cause further nucleus pulposus extrusion, eventually potentially resulting in spinal cord compression.
The treatment, in this case, is then conservative, it is not a surgical disease, and this conservative management consists of strict cage rest, multimodal analgesia for a short period of time, only a few days.
Bladder management, in many cases, is essential and, as I said, gentle hydro and physiotherapy.
The prognosis to return to ambulation is generally good, but in cases of plegia with no nociception combined with certain emorraifying and severe spinal cord injury, these are associated with a much poorer outcome. It is not uncommon in these cases to see long term urinary and faecal incontinence.
12-FIBROCARTILAGINOUS EMBOLIC MYELOPATHY (or fce)
In this disease, the embolasing material is fibrocartilage from the nucleus pulposus of the interactive disc, which may enter the vascular bed that supplies the spinal cord and acts as a clot or as an embolus. Non-chondrodystrophic breeds, especially miniature Schnauzer, are predisposed.
The presentation is very similar to the acute non-compressive disc extrusion, so it is para acute. It tends to be associated with physical activity. Often we see high grades of myelopathy, and this disease is not painful. It is very common as well to see an asymmetry of the neurological deficits.
MRI is required to achieve a diagnosis, and in cases like this exercise, the restriction is not required. On the contrary, early rehabilitation helps with recovery. So again, treatment is basically providing these dogs with nursing care, physio or hydrotherapy, intense bladder management in some of them and again, pain relief. is not required.
The outcome is generally good in the vast majority of the cases, although we need to be aware that it may be guarded to poor in large breed dogs with severe neurological dysfunctions.
13-FELINE ISCHAEMIC MYELOPATHY
This is a similar condition to the canine counterpart. The presentation is the same, so is the peracute onset of clinical signs. It’s especially common in old to geriatric cats, and there is a predilection for the cervical spinal cord segments.
In a relatively high proportion of the cases, we may find an underlying disease, and these are common chronic diseases, hypertension, hyperthyroidism and heart disease.
The treatment is the same as in dogs, but if an underlying disease is found, it should be addressed accordingly. The outcome is good in the majority of the cases.
14-FELINE AORTIC THROMBOEMBOLISM
The presentation is also hyperacute, and it is basically pelvic limbs dysfunction. In these cases, though we may see a hypersthenic area at the level of the pelvic limbs, we may find as well very commonly very weak or even absent femoral pulses, the limbs will be cold, and the nail beds and pulse will likely be cyanotic due to the high hypoperfusion. Frequently we will find an underlying heart disease that in cats will commonly be hypertrophic cardiomyopathy.
Normally the thromboembolism will get lodged at the level of the aortic trifurcation, so performing an abdominal ultrasound and echocardiography will be advised.
The treatment will consist in addressing the cardiopathy, instigating antiplatelet and thrombolytic therapy, pain relief, physiotherapy and bladder management. However, we need to be aware that the outcome tends to be poor, and relapses are frequent.
15-TRAUMATIC SPINAL INJURY
This normally happens as a result of road traffic accidents, fights, falls and bites. Consequently, we may come across vertigo subluxations and fractures. We should take into consideration that not only the spinal cord or the brain are important but also other organs.
In many of these cases, we will have other organs or cavities involved. For this reason, a comprehensive, holistic approach should be made, first of all using the ABC system, to ensure adequate Airway, Breathing and Circulation and then checking, as I said, other concurrent problems like limb fracture, or hemoabdomen or pneumothorax.
In these cases, the handling of the patient will be really careful, and we may have to use chemical restraint. Simple imaging may be adequate in the vast majority of the cases, but it’s important that we take two views as we can miss really important findings.
Conservative management may be considered in these cases if the neurological dysfunction is mild, if there is not a lot of discomforts or if the displacement of the vertebral fracture or subluxation is minimum.
Analgesia will be required, and very importantly, strict rest and limiting the movement of the spine, in these cases using a splint, a brace or a cast. Nursing care will be essential.
Surgery is necessary in some cases, and in order to assess the stability of the spine, the three-column system should be used. So the dorsal column consists of the lamina, the spinal process and their associated ligaments, the middle column consists of the dorsal longitudinal ligaments, the dorsal annulus and the dorsal cortex of the vertebral body the ventral column is the ventral longitudinal ligament, the ventral annulus fibrosus and the ventral cortex of the vertebral bodies.
So if two or more of these columns are disrupted, there is instability and surgery is required. The aim of the surgery is to reduce and stabilise the fracture.
We need to be aware that in cases of spinal cord involvement with fracture or subluxation and if dogs or cats have a Grade 5 myelopathy, so plesia without nociception, the success rate even with surgery is lower than 5%.
16-TAKE HOME MESSAGE
Finally, and to summarise, please use clinical reasoning. Common things are common, and having knowledge of diseases for each group, species, and breed will help us.
These are essential data to consider because we will not approach in the same way an old cat with paraplegia and cold legs: legs and a middle-aged Dachshunds with paresis or a very young beagle with neck pain. And lastly, and please bear that in mind, as you have seen, not all spines are surgical.
Please, if you have any questions, any queries, any doubt, we will be very happy if you send us an email, and we will get back to you as soon as we can!