A method for repeated sampling of cerebrospinal fluid from conscious guinea pigs

A new method is described for obtaining repeated cerebrospinal fluid (CSF) samples from conscious, unrestrained guinea pigs. A simple, disposable cannula is introduced into the cisterna magna by puncturing the atlanto-occipital membrane. The cannula is equipped with a silicone rubber disc which is glued to the membrane, forming a firm but flexible seal. Daily CSF samples of at least 100 microliters can be obtained from unrestrained guinea pigs. Chronically cannulated lactating females continued to suckle their litter successfully, and their milk ejection response was not affected by withdrawal of CSF.