# Correlation of Mechanical Thresholds, Glasgow Composite Measure Pain Scale, and Sharp and Wheeler Grading Scale in Dogs with Acute Thoracolumbar Disc Extrusions

## TL;DR

This study explores how different tools measure pain and neurological severity in dogs with spinal disc issues, finding that mechanical thresholds may better track clinical improvement.

## Contribution

The study introduces mechanical threshold testing as a potentially more sensitive tool for assessing clinical improvement in dogs with disc extrusions.

## Key findings

- Mechanical thresholds correlated with neurological severity but not with pain scores.
- GCMPS and SWGS scores showed no significant correlation or differences over time.
- Mechanical thresholds may better reflect clinical improvement than GCMPS.

## Abstract

Intervertebral disc extrusions are one of the most common neurological disorders in dogs. The compression caused by the extruded disc material leads to neurological deficits such as paraparesis and pain. The objective of this study was to investigate and describe the relationship between neurological severity and pain in dogs with intervertebral disc extrusion. This was investigated using (1) the Glasgow Composite Measure Pain Scale—Short Form, (2) the Sharp and Wheeler Grading Scale, and (3) mechanical threshold testing. The results showed both scores (1) and (3) did not correlate with each other but also did not show any significant differences. In contrast, mechanical thresholds correlated with the neurological severity. Therefore, the measurement of mechanical thresholds could be an additional tool for assessing mechanical sensitivity in dogs with intervertebral disc extrusions.

In dogs with intervertebral disc extrusion (IVDE), the Glasgow Composite Measure Pain Scale—Short Form (GCMPS) and the Sharp and Wheeler Grading Scale (SWGS) are routinely used in the evaluation of pain (GCMPS) and neurological function (SWGS). Additionally, quantitative sensory tests (QSTs) are increasingly being incorporated into veterinary clinical practice for pain characterisation. The aim was to investigate a possible relationship between the GCMPS, the SWGS, and mechanical thresholds (MTs) in 31 client-owned dogs with thoracolumbar IVDEs. Dogs were always assessed in the same order, starting with pain rating using the GCMPS, followed by classifying neurological severity using the SWGS, before determining MTs using a handheld pressure algometer. Dogs were evaluated over a five-day testing period (before surgery and on days one, two, three, and ten after surgery). The GCMPS and the SWGS data remained consistent across all days of testing. No statistically significant correlation or difference was observed between the scores. MTs showed a significant negative correlation with the GCMPS (r = −0.311; p < 0.001) and a positive one with the SWGS (r = 0.282; p = 0.002). The GCMPS and MTs showed a slight divergence in their progression. MTs might be more sensitive than GCMPS in reflecting clinical improvement and should be considered for clinical practice.