Spinal cord injury in the dog has a variety of stages (peracute to chronic) and severity (from complete paralysis) on emergency presentation to a planned appointment for back pain. While many diseases can cause damage to the spinal cord, it is key to recognize which diseases can be managed on an outpatientbasis and when patients should be referred for neurosurgical diagnostics and treatment.
Common Diseases Causing Spinal Cord Injury in Dogs
The most common diseases resulting in spinal cord injury in dogs are intervertebral disc herniation (IVDH includes acute extrusions and chronic protrusions), fibrocartilaginous embolism (FCE), trauma, infection (discospondylitis), and neoplasia. Other differentials can be considered but are less likely.
Dogs affected by intervertebral disease are classically chondrodystrophic and young to middle aged. But it is important to remember that IVDH is the most common cause of spinal cord injury in all dogs.
Several key pieces of patient data are needed to distinguish between these conditions. Acute cases of moderate to severe, painful spinal cord injury are most likely to be intervertebral disc herniation (extrusion) or trauma. Chronic, mild to moderately affected patients are more likely to be intervertebral disc herniation (protrusion) or neoplasia. FCE, a spinal cord injury cause by thromboembolism of arterial blood supply to the spinal cord, is most likely to have a peracute presentation, and is usually non-painful either at initial presentation or within 24 hours of injury.
Variance in Presentation
Severity of spinal cord injury progresses linearly from mild to severe dysfunction. The typical order in which signs occur as the disease progresses or the injury worsens is as follows:
- Hyperesthesia, or pain, appreciated by the client or by the examiner on palpation
- A loss of proprioception detected in an ataxic gait or in decreased to absent postural reactions
- Motor present but the dog is unable to walk independently/without assistance
- Loss of voluntary motor
- Loss of superficial pain sensation (skin sensation)
- Loss of deep pain sensation
Accurate determination of the presence of conscious perception of painful stimuli in dogs can be challenging. A positive conscious response to a painful stimulus in the limb or tail is elicited when the skin or digit is cross-clamped with hemostats resulting in the animal turning to look at the examiner, vocalizing, or attempting to get away from the examiner.
Other more subtle responses, such as an elevation in heart rate, a cessation of panting or dilation of pupils may also be detected. Pain sensation should only be tested in animals who have no motor in a limb, as the presence of motor implies the presence of sensation. Recent literature indicates when examining a dog with pelvic limb paralysis, sensation should be tested in both the pelvic limbs and the tail.
When to Refer for Surgery
Of the diseases covered above, the most likely to require surgical intervention for a successful outcome are intervertebral disc herniation and trauma. It is important to remember that with any spinal cord injury, the best chance of recovery is achieved when intervention occurs as soon as possible.
Once a dog has become ataxic, has progression of deficits or pain that is not relieved with appropriate analgesics and rest, or becomes unable to walk independently, referral should be considered. If a dog initially presents in a non-ambulatory state, ranging from motor intact to absence of deep pain perception, referral is recommended.
What Happens Once a Pet is Referred for Neurosurgical Evaluation?
A board-certified member of our neurosurgical team (which includes veterinary neurologists and general surgeons) will evaluate the patient neurologically and make recommendations for advanced imaging (MRI or CT) and possible surgical treatment. MRI is considered the gold standard diagnostic to determine prognostic changes within the spinal cord prior to surgery and is highly sensitive in the detection of acute and chronic intervertebral disc herniations.
Man y neurosurgeons and general surgeons at MedVet have undergone specific neurosurgical certification training and have years of experience in the surgical treatment of spinal cord injury secondary to disc herniation and trauma. Patients are triaged for advanced imaging as soon as possible, with same day or next day diagnostics and treatment pursued whenever possible as our standard of care.
Most patients are discharged within 24 to 48 hours of surgery and are discharged with oral analgesics, an anti-inflammatory, instructions for strict crate rest for four to six weeks, and sling assistance if necessary.
What is the Expected Outcome?
Dogs with IVDH with intact deep pain sensation have an 85-90% chance of a full recovery, although time to complete recovery can be as long as twelve months in patients who are more severely affected or have been chronically affected. While recent literature suggests the onset of loss of deep pain sensation is not a determining factor in whether recovery will occur, the prognosis for recovery with surgery for dogs and this degree of injury is 50-58%.
If you have questions or would like to discuss this information further, please contact any member of the experienced neurosurgical team at MedVet.
References:
Aikawa, Takeshi, et al. “Long-term neurologic outcome of hemilaminectomy and disk fenestration for treatment of dogs with thoracolumbar intervertebral disk herniation: 831 cases (2000–2007).” Journal of the American Veterinary Medical Association 241.12 (2012): 1617-1626.
Davis, Garrett J., and Dorothy C. Brown. “Prognostic indicators for time to ambulation after surgical decompression in nonambulatory dogs with acute thoracolumbar disk extrusions: 112 cases.” Veterinary surgery 31.6 (2002): 513-518.
Hodgson, Michelle M., et al. “Influence of in‐house rehabilitation on the postoperative outcome of dogs with intervertebral disk herniation.” Veterinary Surgery 46.4 (2017): 566-573.
Jeffery, Nick D., et al. “Choices and Decisions in Decompressive Surgery for Thoracolumbar Intervertebral Disk Herniation.” Veterinary Clinics: Small Animal Practice 48.1 (2018): 169-186.
Jeffery, Nick D., et al. “Factors associated with recovery from paraplegia in dogs with loss of pain perception in the pelvic limbs following intervertebral disk herniation.” Journal of the American Veterinary Medical Association 248.4 (2016): 386-394.
Langerhuus, L., and J. Miles. “Proportion recovery and times to ambulation for non-ambulatory dogs with thoracolumbar disc extrusions treated with hemilaminectomy or conservative treatment: a systematic review and meta-analysis of case-series studies.” The Veterinary Journal 220 (2017): 7-16.
Levine, Jonathan M., et al. “Evaluation of the success of medical management for presumptive thoracolumbar intervertebral disk herniation in dogs.” Veterinary Surgery 36.5 (2007): 482-491.
Levine, J. M., et al. “Magnetic resonance imaging in dogs with neurologic impairment due to acute thoracic and lumbar intervertebral disk herniation.” Journal of Veterinary Internal Medicine 23.6 (2009): 1220-1226.
Olby, Natasha, et al. “Long-term functional outcome of dogs with severe injuries of the thoracolumbar spinal cord: 87 cases (1996–2001).” Journal of the American Veterinary Medical Association 222.6 (2003): 762-769.
Skytte, Ditte, and Hugo Schmökel. “Relationship of preoperative neurologic score with intervals to regaining micturition and ambulation following surgical treatment of thoracolumbar disk herniation in dogs.” Journal of the American Veterinary Medical Association 253.2 (2018): 196-200.
