The effect of prior thecal puncture on cerebrospinal fluid analytes in normal adult horses.

BACKGROUND: Serial cerebrospinal fluid (CSF) analysis might be required in clinical neurologic disease. The effect of lumbosacral (LS) or cervical (C1-C2) centesis on subsequent CSF cytologic analyses has not been investigated in horses. OBJECTIVE: To evaluate the effect of thecal puncture on subsequent CSF analyses ANIMALS: Ten healthy adult horses. METHODS: Prospective study. Horses were randomly assigned to undergo CSF collection twice, 14 days apart, from either the C1-C2 or LS space. After a 4-month washout period, CSF collection was repeated from the alternate site. Continuous data were analyzed using linear mixed-effects models and count data using mixed-effects negative binomial regression. Statistical significance was set at P < .05. RESULTS: There was no significant effect of collection day (day 0 or day 14) for any CSF analytes, including protein concentration (C1-C2: 45 [95% CI: 33-57] mg/dL day 0 vs 49 [95% CI: 39-62] mg/dL day 14, P = .12; LS: 64 [95% CI: 41-100] mg/dL day 0 vs 83 [95% CI: 53-129] mg/dL day 14, P = .37), or nucleated cell count (C1-C2: 2 [95% CI: 1-4] cells/µL day 0 vs 3 [95% CI: 1-4] cells/µL day 14, P = .65; LS: 3 [95% CI: 2-5] cells/µL day 0 vs 5 [95% CI: 3-8] cells/µL day 14, P = .10). There was no significant difference in EPM titer or EPM serum : CSF ratio between days 0 and 14. CONCLUSIONS AND CLINICAL IMPORTANCE: Repeat thecal puncture from the LS or C1-C2 space 2 weeks apart does not appear to impact CSF analytes.

Comparison of 2 collection methods for cerebrospinal fluid analysis from standing, sedate adult horses.

BACKGROUND: Cerebrospinal fluid (CSF) analysis is an important component of the evaluation of horses with neurologic disease. Lumbosacral (LS) centesis is routine, but CSF is also collected from the space between the first and second cervical vertebrae (C1-C2). OBJECTIVES: To compare collection times, CSF cytology results, and equine protozoal myelitis (EPM) titers of CSF collected from the C1-C2 and LS sites. ANIMALS: Fifteen university-owned adult horses with no evidence of neurologic disease, and 9 horses with signs of neurologic disease: 3 university-owned and 6 client-owned. METHODS: Prospective study. Cerebrospinal fluid collection from the LS space and C1-C2 space of each horse was performed in randomized order. Continuous data were analyzed using mixed-effects linear models and count data using mixed-effects negative binomial regression. Statistical significance was set at P < .05. RESULTS: Cerebrospinal fluid collected from the C1-C2 site had a significantly lower mean protein concentration (49 [95% CI: 43-55.8] mg/dL C1-C2 versus 52.1 [95% CI: 45.7-59.3] mg/dL LS; P = .03) and red blood cell count (6 [95% CI: 2-16] cells/µL versus 33 [95% CI: 13-81] cells/µL; P = .02). Collection time, total nucleated cell count, EPM titers, and serum:CSF EPM titer ratios were not significantly different between collection sites. CONCLUSIONS AND CLINICAL IMPORTANCE: Cerebrospinal fluid from the C1-C2 space provides an acceptable alternative to LS CSF collection with decreased likelihood of clinically important blood contamination of samples.