Analysis of cerebrospinal fluid from dogs and cats after 24 and 48 hours of storage

Objective-To compare differential cell counts and cell characteristics of C SF samples analyzed immediately or after storage for 24 and 48 hours at 4 C with and without the addition of autologous serum. Design-Prospective study. Animals-36 dogs and 6 cats. Procedure-CSF samples were collected from the cerebellomedullary cistern an d divided into 250-mu l aliquots. Slides of CSF samples were prepared by us e of cytocentrifugation immediately and after 24 and 48 hours of storage wi th addition of autologous serum (final concentrations, 11 and 29%). Differe ntial cell counts and number of unrecognizable cells were compared among pr eparations. Results-Significant differences in the differential cell counts were not de tected among samples analyzed before or after storage. Although the number of unrecognizable cells increased with storage time, this did not result in a significant effect on cell distribution or diagnosis. Cells in CSF sampl es stored with 11% serum more closely resembled cells in fresh samples than did cells in samples stored with 29% serum. Conclusions and Clinical Relevance-CSF samples collected at veterinary clin ics remote from a diagnostic laboratory or during nonoperational hours may be preserved through the addition of autologous serum. Evaluation of such s amples is likely to result in an accurate diagnosis for at least 48 hours a fter collection.