Comparison of direct in-house cerebrospinal fluid cytology with commercial pathology results in dogs.

ABSTRACT

OBJECTIVES: To investigate the correspondence between in-house direct cytological assessment of cerebrospinal fluid and results from a commercial veterinary pathology laboratory. METHODS: Prospective inclusion of samples from dogs that were presented for investigation of suspected neurological disease and had cerebrospinal fluid samples submitted to a commercial pathology laboratory for analysis. A board-certified veterinary pathologist assessed all cerebrospinal fluid samples, and a line smear was assessed in-house by two observers. Nucleated cell count, red blood cell count and differential cell counts were recorded and compared. RESULTS: In-clinic and commercial pathology nucleated cell counts and red blood cell counts were strongly correlated. In-house line smear results were compared with the gold standard of a defined dichotomous rating of 'increased nucleated cell count' provided by the external pathology service. Sensitivity was 93% and specificity 80% for samples with at least two cells per linear field. CLINICAL APPLICATION Although not a replacement for the assessment of cerebrospinal fluid samples by specialist veterinary pathologists, this method can provide rapid and clinically meaningful information before externally processed sample results are available.