Interpretation of cerebrospinal fluid analysis from recumbent cows using different thresholds of red blood cell count.

Abstract

BACKGROUND: Hemodilution of the cerebrospinal fluid (CSF) could confound interpretation of results. Accurately predicting total nucleated cells count (TNCC) and total protein concentration (TPC) attributable to hemodilution is difficult. OBJECTIVE: To determine the effects of hemodilution on TPC and TNCC in bovine CSF. METHODS: Retrospective review of CSF analysis results of downer dairy cows treated at Centre hospitalier universitaire v&#xe9;t&#xe9;rinaire between January 2006 and December 2014. Descriptive statistics were performed using 3 scenarios. RESULTS: Among the 235 samples included, red blood cell (RBC) count (RBCC) ranged from 0 to 869&#x2009;220 RBC/&#x3bc;L (median&#xa0;=&#xa0;6.6), TPC ranged from 0.04 to 6.51&#x2009;g/L (median&#xa0;=&#xa0;0.27), and TNCC ranged from 0 to 7500 cell/&#x3bc;L (median&#xa0;=&#xa0;1.1). Among the 157 samples that had <30 RBC/&#x3bc;L (a threshold used in other species), TPC and TNCC varied between 0.13 and 1.06&#x2009;g/L (median&#xa0;=&#xa0;0.27) and between 0 and 31.4 cell/&#x3bc;L (median&#xa0;=&#xa0;0.6), respectively. Eighty-four samples had TPC&#x2009;<0.25&#x2009;g/L and TNCC&#x2009;&#x2264;4.5 cell/&#x3bc;L. Among those 84 samples, RBCC varied between 0 and 1290 RBC/&#x3bc;L (median&#xa0;=&#xa0;4.7). In 20 samples, TNCC was 0 with a variation in RBCC between 0 and 840 RBC/&#x3bc;L (median&#xa0;=&#xa0;3.9). No strong correlations between RBCC and TNCC and TPC were found. CONCLUSIONS: A cutoff around 200 RBC/&#x3bc;L is proposed as clinically meaninful in bovine CSF. Results between 200 and 1290 RBC/&#x3bc;L are equivocal.