Recovery of ambulation in small, nonbrachycephalic dogs after conservative management of acute thoracolumbar disk extrusion

Abstract

Background: Currently, low-level evidence suggests loss of ambulation associated with acute thoracolumbar disk extrusion is best treated by decompressive spinal surgery. Conservative management can be successful, but the proportion of dogs that recover and the fate of herniated material are uncertain.

Objectives: Determine the proportion of nonambulatory dogs with conservatively treated acute thoracolumbar disk extrusion that recover ambulation and measure the change in spinal cord compression during the first 12 weeks after presentation.

Animals: Seventy-two client-owned nonambulatory dogs with acute thoracolumbar intervertebral disk extrusion.

Methods: This is a prospective cohort study. Enrolled dogs underwent magnetic resonance imaging at presentation and owners were provided with conservative management recommendations. Imaging was repeated after 12 weeks. Recovery of ambulation was defined as 10 consecutive steps without falling. Spinal cord compression was determined from the cross-sectional area of the vertebral canal and extradural compressive material at the lesion epicenter. The association between recovery and change in compression over the 12-week observational period was examined.

Results: Forty-nine of fifty-one (96%; 95% confidence interval [CI], 87%-99%) of deep pain-positive and 10/21 (48%; 95% CI, 28%-68%) of deep pain-negative dogs recovered ambulation within the 12-week period. The median time to ambulation was 11 and 25 days for deep pain-positive and -negative dogs, respectively. Reduction in spinal cord compression varied among individuals from minimal to complete and apparently was unrelated to the recovery of ambulation.

Conclusions and clinical importance: A high proportion of conservatively treated dogs recovered ambulation after conservative management of acute thoracolumbar disk herniation. Recovery was not dependent on the resolution of compression.

Keywords: compression; contusion; disk herniation; spinal cord injury.

FIGURE 1

Sagittal HASTE MR image showing CSF attenuation measurement (A), and T2 transverse MR image showing cross‐sectional measurement of extradural compressive material (B). CSF, cerebrospinal fluid; HASTE, half Fourier single‐shot turbo spin echo; MR, magnetic resonance

FIGURE 2

Flow chart of patient inclusion and exclusion

FIGURE 3

A combined scatter and box and whisker plot showing time to ambulation in DPP (A) and DPN (B) dogs as individual data points (circles), median, quartiles (box), and upper and lower extremities (bars). DPN, deep pain negative; DPP, deep pain positive

FIGURE 4

A flow chart tracing DPN dogs through the study period. DPN, deep pain negative

FIGURE 5

A scatter plot, box plot, and raincloud plot showing compression visible on initial and repeat imaging

FIGURE 6

Transverse T2‐weighted images showing near‐complete regression of extradural compressive material (solid arrows) between 0 (A) and 12 weeks (B) and little to no change (C and D). The spinal cord is annotated using dotted arrows. Note the hyperintense spinal cord (B) suspected to be gliosis

FIGURE 7

Scatter plots, box plots, and raincloud plots showing compression visible on initial and repeat imaging for those that recovered (A) and those that did not (B)

FIGURE 8

A combined scatter, box, and raincloud plot of the reduction in compression (initial %‐repeat %) by recovery of ambulation