how do I differentiate and treat lumbosacral pain versus radiculopathy in dogs?

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Lumbosacral pain and radiculopathy in dogs are distinct but frequently co-occurring conditions that require integration of physical examination, the LSPain Scale, and MRI to differentiate and direct treatment. --- Differentiating Lumbosacral Pain from Radiculopathy Lumbosacral pain is identified by behavioural responses to palpation of the lumbosacral region, scored using the LSPain Scale (0 = no pain to 3 = severe pain). This 4-point ordinal instrument has demonstrated strong convergent and discriminant validity, inter- and intra-rater reliability, and responsiveness to treatment across experience levels, making it the recommended standardised tool for both initial assessment and monitoring.8 Pain responses on lumbosacral palpation overlap substantially with hip conditions, so physical examination alone is insufficient to localise the pain source.1 Radiculopathy is distinguished by nerve root signs: ipsilateral hind limb lameness, proprioceptive deficits, and limb-specific neurological changes. Unilateral lumbosacral MRI findings are associated with clinical signs on the ipsilateral hind limb in 85% of dogs.10 Radiculopathy affecting the L7 spinal nerve is the strongest predictor of lumbosacral pain specifically, while intervertebral disc (IVD) extrusion is the primary pathology associated with lumbar pain.1 On MRI, L7 radiculopathy manifests as nerve root enlargement, nerve root hyperintensity relative to surrounding connective tissue on dorsal oblique gradient echo short time inversion recovery sequences, and changes in nerve root shape, size, or position on transverse T1-weighted sequences.10 Loss of foraminal fat signal on MRI is the key screening finding for foraminal stenosis and radiculopathy. Of 480 neuroforamina evaluated, loss of foraminal fat signal was present in 364, of which 87.9% also showed concurrent nerve root changes.10 Foraminal stenosis, IVD bulging, and IVD protrusion are all significantly associated with lumbosacral pain on multivariable anal