Evaluation of decreased glucose levels in the cerebrospinal fluid of dogs

Objective: The aim of the study was to evaluate the glucose ratio (glucose level in the cerebrospinal fluid [CSF]/blood glucose level) as a quickly available marker for detecting bacterial meningoencephalomyelitis (BM). Material and methods: Blood and CSF samples of 328 dogs were reviewed and evaluated retrospectively. Following the neurological diagnosis, the dogs were assigned to seven different groups: steroid-responsive meningitis-arteritis (SRMA), intervertebral disc disease (IVDD), neoplasia of the central nervous system (N), idiopathic epilepsy (IE), bacterial meningoencephalomyelitis (BM), meningoencephalomyelitis of other origin (ME) and healthy dogs. Results: The median of the CSF-glucose level (mmol/l) and the median of the glucose ratio in the SRMA group displayed the lowest values and differed significantly from the CSF-glucose levels of dogs in the groups IVDD, N, IE and healthy dogs (CSF-glucose level: p<0.01; glucose ratio: p<0.05). In the BM group, both parameters did not differ significant- ly from other groups, but displayed similar low levels as in the SRMA group. There was a negative correlation between the CSF cell count and the CSF-glucose ratio (Spearman correlation coefficient –0.322, p=0.01, R²=0.108). Conclusion: The CSF-glucose concentration cannot be used as a distinct marker to differentiate BM from other inflammatory CNS-diseases, especially from SRMA usually accompanied by severe pleocytosis. Low CSF-glucose levels appear to be caused by elevated CSF cell counts rather than by bacterial metabolism. Clinical relevance: For a definitive diagnosis of bacterial meningoencephalomyelitis in dogs, the detection of microorganisms remains necessary.