A spinal tap is a procedure that collects the fluid that covers the brain and spinal cord. In dogs and cats we can collect from a spot behind their skull (cerebellomedullary cistern) or the lower lumbar spine, sometimes both. Because this fluid bathes the central nervous system it can give more information at a cellular level of what is going on especially regarding inflammation. It also helps complement findings on MRI and can
help us obtain a definitive diagnosis. In general, spinal tap is performed after advanced imaging to ensure that the spinal tap is necessary (as not all conditions require this for diagnosis). In particular with brain diseases, the MRI helps us ensure that spinal tap is safe to perform.