Cerebrospinal fluid lactate in dogs with inflammatory central nervous system disorders

Abstract Background Cerebrospinal fluid (CSF) lactate is frequently used as a biomarker in humans with inflammatory central nervous system (CNS) disorders including bacterial meningitis and autoimmune disorders such as multiple sclerosis. Hypothesis Cerebrospinal fluid lactate concentrations are increased in a subset of dogs with inflammatory CNS disorders. Animals One hundred two client‐owned dogs diagnosed with inflammatory CNS disease. Methods Case series. Cases were identified both prospectively at the time of diagnosis and retrospectively by review of a CSF biorepository. Cerebrospinal fluid lactate was analyzed with a commercially available, handheld lactate monitor. Subcategories of inflammatory disease were created for comparison (eg, steroid‐responsive meningitis arteritis, meningoencephalitis of unknown etiology). Results Cerebrospinal fluid lactate concentrations were above reference range in 47% of dogs (median, 2.5 mmol/L; range, 1.0‐11.7 mmol/L). There was no significant difference in lactate concentrations between disease subcategories (P = .48). Significant but weak correlations were noted between CSF lactate concentration and nucleated cell count (r = .33, P < .001), absolute large mononuclear cell count (r = .44, P < .001), absolute small mononuclear cell count (r = .39, P < .001), absolute neutrophil cell count (r = .24, P = .01), and protein (r = .44, P < .001). No correlation was found between CSF lactate concentration and CSF red blood cell count (P = .58). There was no significant association of CSF lactate concentration with survival (P = .27). Conclusions and Clinical Importance Cerebrospinal fluid lactate concentrations could serve as a rapid biomarker of inflammatory CNS disease in dogs.