Ambulation in Dogs With Absent Pain Perception After Acute Thoracolumbar Spinal Cord Injury

Abstract

Acute thoracolumbar spinal cord injury (SCI) is common in dogs frequently secondary to intervertebral disc herniation. Following severe injury, some dogs never regain sensory function to the pelvic limbs or tail and are designated chronically "deep pain negative." Despite this, a subset of these dogs develop spontaneous motor recovery over time including some that recover sufficient function in their pelvic limbs to walk independently without assistance or weight support. This type of ambulation is commonly known as "spinal walking" and can take up to a year or more to develop. This review provides a comparative overview of locomotion and explores the physiology of locomotor recovery after severe SCI in dogs. We discuss the mechanisms by which post-injury plasticity and coordination between circuitry contained within the spinal cord, peripheral sensory feedback, and residual or recovered supraspinal connections might combine to underpin spinal walking. The clinical characteristics of spinal walking are outlined including what is known about the role of patient or injury features such as lesion location, timeframe post-injury, body size, and spasticity. The relationship between the emergence of spinal walking and electrodiagnostic and magnetic resonance imaging findings are also discussed. Finally, we review possible ways to predict or facilitate recovery of walking in chronically deep pain negative dogs. Improved understanding of the mechanisms of gait generation and plasticity of the surviving tissue after injury might pave the way for further treatment options and enhanced outcomes in severely injured dogs.

Nervous system modulation through electrical stimulation in companion animals

“…In humans, the influence of the corticospinal tract is greater than in dogs and cats. The corticospinal tract is less developed in domestic animals, especially dogs, resulting in difficulties to perform complex and precise movements [ 2 , 3 ].…”

Outcome in Cats with Acute Onset of Severe Thoracolumbar Spinal Cord Injury Following Physical Rehabilitation

“…SW is commonly considered a reflex stepping gate, generated by the central pattern generator, independent of supraspinal or sensory input. However, gait generation is a complex process and different mechanisms may influence the recovery of motor function below the level of severe injury [ 12 ]. In fact, in naturally occurring spinal cord injury, development of ambulation in patients without DPP may reflect a reorganized central pattern generator in complex coordination with multiple other factors, such as spared supraspinal influence, a certain threshold of motor neuron pool excitability, peripheral sensory input, and specific locomotor training [ 12 ].…”

“…However, gait generation is a complex process and different mechanisms may influence the recovery of motor function below the level of severe injury [ 12 ]. In fact, in naturally occurring spinal cord injury, development of ambulation in patients without DPP may reflect a reorganized central pattern generator in complex coordination with multiple other factors, such as spared supraspinal influence, a certain threshold of motor neuron pool excitability, peripheral sensory input, and specific locomotor training [ 12 ]. To the best of the authors’ knowledge, SW has been described in cats only in experimental contexts, and our data showed the acquisition of SW in a relevant percentage of the study population under natural conditions.…”

“…The information on group 2 was gathered by writing a record of the first examination at the time of the patient’s admission and by interviewing the owners by phone at the time of this study, with the aim of collecting data regarding the acquisition, or not, of an involuntary ambulatory status (outcome). Ambulatory status was defined as the ability to rise and take at least 10 consecutive weight-bearing steps unassisted without falling [ 12 ]. Cats without a minimum of a 3-month follow-up were excluded.…”

“…In cats without DPP, at the admission and during the whole treatment, the acquisition of a SW gait was detailed. Recently, SW was defined in dogs as an independent ambulation in a “deep pain negative”(without DPP) dog, typically characterized by lack of coordination between thoracic and pelvic limbs, difficulty turning, or going backward, intermittent falling (especially when changing directions), frequently intact toe knuckling response but without hopping, and increased spasticity [ 12 ]. In this study, in addition to the features mentioned above, feline patients were identified as spinal walkers if they could walk for an extensive period of time (>15 min) and, in the case of falling, they were able to regain a standing posture without assistance and to resume walking [ 5 ].…”