Somatosensory and visual evoked potentials and brainstem auditory evoked responses in osteoarthritic cats with chronic pain - a comparative study.

Although chronic pain in feline osteoarthritis involves neuro-sensitization, the associated sensory changes have not been studied. Cats with osteoarthritis (n = 20) and healthy controls (n = 6) were assessed for peripheral (paw withdrawal threshold, PWT) and spinal (response to mechanical temporal summation, RMTS) sensitization, with lower values indicating higher neuro-sensitization. Functional impairment was assessed using the Montreal Instrument for Cat Arthritis Testing, for Use by Veterinarians [MI-CAT(V)], with higher scores indicating greater impairment. Cerebral sensory integration was evaluated using cortical somatosensory evoked potential (CSEP), brainstem auditory evoked response (BAER), and visual evoked potential (VEP) under dexmedetomidine sedation. The amplitude and latency of action potentials were recorded. The Mann-Whitney U test and Spearman's rank correlation (coefficient = ρ) were applied (α = 0.05). Cats with pain showed increased CSEP and BAER latency and amplitude (p < 0.032) but decreased VEP latency and increased amplitude (p < 0.038) compared to healthy cats. The PWT was negatively correlated with CSEP latency and amplitude (ρ = -0.51 to -0.43, p < 0.037) and BAER latency (ρ = -0.80 to -0.60, p < 0.039), while the RMTS was negatively correlated with CSEP latency (ρ = -0.48, p = 0.017). In contrast, the PWT (ρ = 0.71 to 0.76, p < 0.010) was positively correlated with VEP latency. The MI-CAT(V) score correlated with CSEP amplitude (ρ = 0.62, p = 0.006), BAER latency (ρ = 0.72 to 0.90, p < 0.008), and VEP latency (ρ = -0.73 to -0.65, p = 0.023). Sensory processing is altered in cats with osteoarthritis-associated chronic pain, suggesting differential inhibitory control mechanisms.