Indications for performing this procedure: Collection of cerebral spinal fluid is indicated in clinical cases showing signs of encephalopathy including ataxia, cranial nerve deficits, or other neurologic deficits.
Fluid collection: Cerebral spinal fluid is
collected from one of two places in the equine patient. The atlanto-occipital and
lumbo-sacral sites are used depending on the suspected
lesion location. For a cervical lesion, collection from the atlanto-occipital joint may provide more information than a
lumbo-sacral tap due
to the proximity of the lesion. A sedate and relaxed horse may be
collected while standing from the lumbo-sacral site, however, general anesthesia
is usually required for safe collection from the atlanto-occipital site.
A 10 ml sample can be safely removed from an average sized adult horse.
From a foal, a sample of 5 ml may be removed.
Sample analysis: It is important for the
sample to be handled carefully and analyzed quickly due to the rapid degradation
of white blood cells in the CSF. A hematocytometer may be used to calculate
the red and white blood cell counts. Normally, the CSF will appear
colorless and clear. Total protein is normally between 40 and 110 mg/dl in
the horse. Values higher than that will cause the CSF to be come more
opaque. Red blood cell count should be approximately 500/ul or less.
Cells
present in excess of that will cause the fluid to appear pink. A yellow
discoloration is called Xanthochromia and indicates the presence of blood
pigments from hemoglobin breakdown. If inflammation is indicated by the
presence of leukocytes, then gram staining is indicated to detect
bacteria. If no bacteria are seen, serology can be performed for possible
agents causing the disease.
The table below is not all inclusive, but
can give a general idea on interpretation of abnormalities.
| Parameter | Normal | Abnormal | Possible Interpretation |
| Color | colorless | 1. pink, brown, or yellow 2. black 3. Off-white, gray |
1. Blood pigments, hemorrhage, or hemoglobin 2. Melanoma 3. High protein or cells |
| Consistency | Slightly viscous | 1. Foamy 2. Turbid |
1. High protein levels 2. High cell counts |
| Total Protein | 40-110 mg/dl | Above normal values | 1. Vascular compromise, encephalitis, meningitis, neoplasia, spinal chord compression |
| Total Cell Count | 1. <5
WBC/dl 2. No RBC |
1. >5 WBC/dl 2. Presence of RBCs |
1. Infection, abscess, inflammation, necrosis, neoplasia 2. Hemorrhage, inflammation |
For more information. . .