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The intervertebral discs are situated between each spinal vertebra and act as a cushion to provide strength and flexibility to the spine. They have a semi-liquid centre called the nucleus pulposus, which is protected by a fibrous outer layer (annulus fibrosus). The term ‘herniation’ means that the structure of the disc is damaged allowing the disc material to move and cause pressure on the spinal cord. This tends to occur in the thoracolumbar (low back) region and in the cervical (neck) region. There are 2 main ways in which the disc can herniate. 1. A healthy disc can rupture as a result of trauma such as a road traffic accident or a fall from height. 2. Degenerative disc disease (Intervertebral disc disease - IVDD) The majority of disc protrusions are secondary to underlying disc degeneration. This can occur in 2 ways:
Type I: Occurs because the nucleus loses its gelatinous nature and the disc becomes more cartilaginous. The annulus fibrosus tears allowing the nucleus to bulge out and put pressure on the spinal cord (disc extrusion). Common in chondrodystrophic breeds such as Dachshunds, Shi Tzu, and Pekingese. This process can start occurring as young as 2 months in affected breeds but signs usually show around 2 to 4 years of age. Symptoms will occur suddenly.
Type II: The discs lose their water and protein content and slowly become more fibrous. This causes progressive thickening of the outer layer of the disc, which presses up on the spinal cord (disc protrusion). This type of degeneration is more common in the regions of the spine that are particularly exposed to physical stress (the lower neck, mid-back and lower-back) and is more common in older large-breed dogs. The signs are usually less severe and slower in onset compared to type I.
Symptoms and diagnosis
Spinal pain is the main symptom of disc disease. The dog may have a low head carriage, hunched back, and be reluctant to move/exercise or cry out when moving. Neurological signs may also be present and will depend upon the location of the lesion. Symptoms can range from mild weakness, loss of coordination and ataxia to paralysis, faecal or urinary incontinence and loss of sensation in the legs. Definative diagnosis can only be made using either myelography (X-rays taken after the injection of dye around the spinal cord so that problems can be identified within the spinal cord), CT (computed tomography) or MRI (magnetic resonance imaging). These tests can help confirm if there is a disc protrusion, where it is and will also show up other causes.
Treatment
Treatment depends on the location of the lesion and the severity of the symptoms. In some cases dogs will respond to conservative management, although recurrence in the same area is quite common. Strict cage rest is required initially and drug management to reduce pain and inflammation. Acupuncture may help with pain relief. Physiotherapy is essential in maintaining joint motion and muscle length and assisting the recovery of normal movement patterns and function. When appropriate hydrotherapy can help to promote recovery and improve strength. Where surgery is required an operation is performed to relieve the pressure on the spinal cord. Usually a slot in the vertebral bone is made and then the disc material removed. The recovery rate is far more rapid in dogs that receive surgery within 48 hours of onset of symptoms.
2. Fibro-cartilaginous embolism (FCE) Description and cause
Fibro cartilage is a substance found within the centre of the intervertebral discs. Some how this substance makes its way in to the circulation of the spinal cord. The fragment causes the blood vessel to become blocked: an embolus. The portion of the spinal cord affected will die causing neurological defects. No one fully understands why this occurs. Any dog can be a victim of FCE. About half those affected are giant breed dogs. Breeds such as Dachshunds and Basset Hounds are less susceptible because their disc material tends to be too hard to be involved. It is thought that miniature Schnauzers may have an increased risk because they tend to have excess fat levels and cholesterol circulating in their blood. FCE dogs tend to be young, between 3 and 6 years old and often present with FCE after some kind of exercise injury or trauma.
Symptoms and diagnosis
The ischaemic damage to the spinal cord from the lack blood supply causes non-painful neurological damage. The symptoms come on very suddenly and are very variable depending on the location and the severity of the damage. There is a 50% chance that only the lumbar spine is affected, which means that only the hind limbs will be affected. Usually one side is worse than the other. The limbs may either have increased muscle tone and ‘spasticity’ or decreased muscle tone and ‘flaccidity’. Your dog may not be able to use his back legs properly. The toes may knuckle under or he may not be able to use them at all. Many dogs are simply weak in the back legs and may or may not need help to get around. Occasionally all four limbs can be paralysed.Diagnosis is based on clinical presentation and exclusion of other spinal cord injuries via myelogram or MRI.
Treatment
Medications such as corticosteroids can be used to relieve spinal cord swelling and to prevent collateral damage. Surgery is not indicated in the treatment of FCE. After your dog has received early medical management, intensive nursing care and physiotherapy are required. The goal is to maintain muscle tone while the spinal cord tissue heals. Most damage to the spinal cord occurs in the first 24 hours. After this the symptoms will not get worse. How well your dog recovers is very much dependent on how much loss of function there is to begin with. Early referral to physiotherapy and hydrotherapy is key and can help to improve movement, balance and strength. See our therapy testimonials for Barney and Maisie
3. Cervical vertebral malformation
Description and cause
This is an abnormality of the lower cervical vertebrae and is often referred to as ‘Wobbler’ syndrome. Other names you may hear are cervical vertebral instability and caudal cervical spondylomyelopathy. It is characterised by several changes of the anatomy of the cervical spine. Abnormal bone formation in the cervical spine (neck) occurs allowing abnormal movement of one vertebra against the one in front of it therefore pushing onto the spinal cord and creating neurological deficit. Mostly large and giant breed dogs are affected such as Doberman Pinschers, Great Danes, Basset hounds, Old English sheepdog, Saints and Rhodesian Ridgebacks.
Symptoms and diagnosis
Symptoms can be sudden or slowly progressive. Signs are characterised by generalised progressive ataxia (poor coordination) and weakness. Early signs may include a stiff neck and low head carriage. Symptoms can include mis-stepping, poor foot placement, wobbly gait, and reduced limb sensation, dragging feet and poor coordination. This can progress to stumbling, frequent falling and paralysis of all limbs. The symptoms depend on the location of the compression and the severity of it. In slower progressive cases, symptoms are not dissimilar to that of chronic degenerative myelopathy (CDM) seen in the German shepherd breed. There is no pain. If pain is present cervical disc herniation may be suspected. Symptoms can start at any age.Diagnosis will be made in part from the clinical exam carried out by your veterinary surgeon but a definitive diagnosis is based on spinal imaging such as X-Rays, MRI and/or myelogram of the neck.
Treatment
Non-surgical treatment includes anti-inflammatory doses of corticosteroids and in some cases a neck brace. Exercise is restricted. This may bring about some improvement however in some cases the underlying disease process continues and neurological symptoms may get worse. Surgery may be indicated in this scenario but will be discussed with you by your vet. The aim is to decompress the spinal cord and stabilise the segment. 75% of patients do well with surgery (Shealy et al, In Millis et al, 2004). Recovery depends on the severity of neurological deficits and is worse for patients with long-term paralysis. Patients may be left with long-term reduced function and disability. Physiotherapy plays an important part in patient care both in the acute post-operative phase and with long term management. Physiotherapy can help to improve muscle tone, begin assisted weight bearing exercises and progress to sling walking. As mobility improves hydrotherapy and underwater treadmill are useful in helping patients regaining independent mobility. Extended rehabilitation is often required in the proper management of this disabling condition. Canine carts (canine wheelchairs) can offer temporary assistance in the recovery process and are also appropriate for long-term management for those dogs with permanent disability that will not regain full function.
4. Spinal injury/trauma
Description and cause
Major traumatic insults to the body can result in injury to the head and spinal cord. Road traffic accidents and falls are the most common causes of injury. Spinal injuries may consist of vertebral subluxation or luxation, fracture, fracture/luxation or traumatic disc herniation. Fractures most commonly occur in the thoracolumbar region or sacral area as a result of trauma. More rarely seen in the cervical spine (neck region). Can also be as a result of pathological changes to the spinal column or through developmental weakness.
Symptoms and diagnosis
As with any trauma patient, urgent veterinary assessment and care is needed to treat concurrent life threatening injuries and then later fully assess the patient to localise the injury and determine the severity of any neurological deficits. Signs are dependant on the nature of the injury but pain and reduced function will usually occur. There may be neurological symptoms like weakness with walking or paralysis of limbs. Diagnosis is based on clinical examination and further tests such as x-ray and myelogram/CT.
Treatment
Treatment will depend entirely on the nature and the extent of the injury. If a stable fracture is present and there are no neurological symptoms then conservative management may be appropriate. This includes strict cage rest for 4 to 6 weeks, the use of a splint to immobilise the area and adequate pain relief. If this is unsuccessful, the fracture-luxation is unstable, persistent compression of the spinal canal is evident or if there are progressive neurological symptoms then surgery is indicated. An operation will be performed to relieve any pressure on the spinal cord and stabilise the spine.Physiotherapy plays a vital role in recovery following spinal surgery. Acupuncture may assist with pain relief and hydrotherapy can maximise strength and function.
5. Discospondylitis
Description and cause
This is an infection of the intervertebral discs and adjacent vertebral bodies, which causes an inflammatory response involving the associated spinal cord or nerve roots. It can occur as a result from primary infection elsewhere in the body such as a urinary tract infection or infection in the skin or mouth. Direct infection may occur from penetrating wound into the disc space or vertebra or from surgery. Symptoms and diagnosis Discospondylitis most commonly affects large, middle aged dogs. Small dogs and cats are rarely affected. The most common initial sign is pain and discomfort of the affected region in the spinal column. It can vary from mild to extreme and onset can occur over several days or weeks. Neurological signs such as poor co-ordination (ataxia) and paralysis can be seen in some patients. Patients may also show signs of illness such as fever, lethargy, depression and weight loss, though not always. Diagnosis is based on clinical features and diagnostic imaging. X-ray will usually identify the problem although in the early stages of the disease MRI or CT may be more sensitive to the changes in the spine. If severe neurological symptoms are present a myelogram may be performed to determine the site and severity of spinal cord compression. A full blood count, urine culture and blood cultures are performed as well.
Treatment
Initial treatment will consist of antibiotics, cage rest and pain relief, which should start to make a positive effect within 5 days. Treatment continues for 8 weeks to make sure the infection is completely cleared. Most animals recover with appropriate medical management. Surgery is rarely necessary but considered if conservative treatment is ineffective, if there is evidence of cord compression or if substantial neurological deficits are present. Physiotherapy and hydrotherapy is indicated in more severely affected patients after a positive response to medical management has been achieved.
6. Neoplasia
Cause and description
It is important to be aware that cancerous tumours within the spinal column can present very similarly to other neurological conditions. Spinal neoplasia is more common in middle aged or older animals although there are variations.
Symptoms and Diagnosis
Can be sudden but are usually slow and progressive. Focal spinal pain is the main symptom followed by progressive neurological deficits as the spinal cord becomes involved. These include ataxia and loss of movement and sensation. Diagnosis is based on the history, physical examination and diagnostic imaging. X-rays will identify bony changes within the vertebral bodies. If neoplasia is suspected then chest will be taken to screen for metastases (secondary tumours). CT-myelography and MRI may be carried out to identify the extent of spinal cord involvement. Definitive diagnosis will involve a surgical biopsy and exploration of the area.
Treatment
Medical management is concerned with pain relief and promoting quality of life. Analgesics and corticosteroids can be used. Chemotherapy may be appropriate for some tumours. Definitive treatment consists of surgical removal of the tumour. Surgical procedures are often not curative but can prolong quality of life. Radiotherapy may be used along side surgery depending on the tumour type. Prognosis depends on the tumour type. Physiotherapy can be appropriate after surgery to promote comfort and maximise function so far as is reasonable. This is a progressive disease and as the condition and ability of the patient deteriorates physiotherapy will no longer be appropriate. Further management is based on quality of life issues and the wishes of the owner and can be discussed if desired with the veterinary surgeon and with other professionals involved in the long term care of the patient
7. Neuromuscular Disease
Cause and description
A larger number of conditions fall into this category but the most relevant to the UK is Myasthenia Gravis. Nerve impulses from the spinal cord cannot be conveyed to the muscles effectively due to a problem with the neuromuscular junction and function is impeded. The disease falls into 2 types, congenital and acquired. In the congenital disease, affected puppies are born without normal neuromuscular junctions and have impaired function. Unfortunately there is no effective treatment. Myasthenia gravis has been described as a recessive genetic disease in the Jack Russell terrier, the Springer Spaniel, and the Smooth Fox Terrier. The miniature dachshund gets a congenital form, which actually resolves with age. Acquired myasthenia gravis is a so-called “Autoimmune disease,” meaning that the immune system begins to destroy the neuromuscular junctions. Nerve impulses cannot get through to the muscles. The muscles affected depend on which junctions have been destroyed.
Symptoms and diagnosis
Muscle weakness is the main symptom, affecting the eyes, facial expression and limbs. Reduced exercise tolerance and early fatigue might be noticed which can progress to worsening function and mobility. There may be impaired swallowing. Diagnosis involves a blood test to identify for antibodies against the acetylcholine receptors (involved in normal neuromuscular junction function) Treatment For the acquired disease, therapy concentrates on stopping the immune system’s attack on the nerve pathways by using immunosuppressive drugs and medication to help prolong the function of undamaged receptors so that more signals can get to the muscles. In some cases the disease goes into remission without treatment. Physiotherapy is indicated to help maintain normal joint and muscle range during reduced function and to encourage normal movement, mobility and function during the rehabilitation phase. Hydrotherapy can help to maximise strength and improve function.
8. Peripheral neuropathies
Description and cause
Peripheral nerves are those nerves that are outside of the brain and have exited the spinal cord. They supply the limbs to ensure normal sensation and movement. A peripheral nerve can be damaged anywhere along its length. A single nerve can be affected or several (polyneuropthy). This can be congenital or acquired. Acquired peripheral neuropathies can occur as a result of trauma, immune mediated disease, endocrine conditions (e.g. diabetes, hypothyroidism), toxins and infections and these are the types we are more likely to see at Meadow Farm.
Symptoms and diagnosis
Traumatic neuropathies tend to be unilateral, affecting only one limb or a portion of the limb depending on the site of the nerve damage. Sensory and motor loss commonly occurs together. This causes weakness, muscle wasting and loss of reflexes. This can severely impair function in the affected limb or limbs. Diagnosis is based on clinical exam and history of symptoms i.e. any underlying inflammatory condition or infection, trauma or other predisposing factors. EMG (electromyography) and nerve conduction studies will identify which muscles are without nerve supply and whether some or all nerve fibres are affected. TreatmentSurgical options are available for repair of complete traumatic lesions however the nerve itself can regenerate over time. The time taken is dependant on the severity of the nerve damage. For other acquired peripheral motor neuropathies, recovery time is variable, but may be prolonged. Peripheral nerve diseases can be benign, meaning that with time and treatment, many animals will recover from them. Treatment will differ according to the severity of the functional impairment. Physiotherapy is important for recumbent dogs to prevent them from developing pressure sores and to maintain joint and muscle range. It can also assist with the recovery of movement, strength and function. Hydrotherapy may help improve strength and increase joint movement once function has started to return. Electrical muscle stimulation carried out by a physiotherapist may be used to prevent muscle atrophy and maintain muscle fibre integrity during the period of nerve regeneration.