Abstracts

Recording the EEG in dogs with epilepsy has always been difficult as the only suitable electrode available was the needle electrode (NE). The NE were easily dislodged, produced spontaneous artifact, had high impedances thus it was not possible to maintain viability of the NE for long periods of time. The NE were rigid electrodes and not conducive to long-term EEG monitoring (LTM). Epilepsy in dogs (4-5%) is more prevalent than in humans (1-2%). Epilepsy in dogs is also naturally occuring with similar clinical presentations and classifications. Therefore, being able to more easily and reliably record the EEG in dogs may provide better access to a naturally occuring epilepsy model for investigating new and established treatment methodologies. Using a new subdermal wire electrode (SWE) that was originally developed for use with patients in the neuro ICU (1), the difficulties and limitations of recording the EEG in dogs has been made easier with improved EEG quality and LTM potential. The SWE consist of multi-stranded, pure silver wire with a Teflon coat. It is placed using a 23 gauge hypodermic needle. The SWE is very similar to the original chronic sphenoidal electrode (2,3) developed for LTM in patients with epilepsy. By also including a very small, light-weight connector system, the recording electrodes and harness can be easily fixed on the scalp/collar of the dog to permit LTM by cable, RF or ambulatory methodology. The SWE records with a [lt]5K[Omega] impedance, is easily/quickly placed, and has high frequency as well as DC capability. The SWE records a high quality EEG and has significantly lower artifact during normal movements compared to the NE. The small size, low inertia and low profile of the SWE lends itself to LTM procedures. The SWE can also be used to record the animal[apos]s EKG. The SWE is MRI, CT, and rTMS compatible. A new subdermal wire electrode has been used to record the EEG in dogs with epilepsy. The SWE is superior in all aspects to the traditional needle electrode. The SWE has lower impedance, less spontaneous artifact and can record down to DC. In conjunction with a dedicated, light-weight connector, the potential to record the EEG from the dog in a similar manner as per LTM in humans is now possible. The SWE and its ability to record EEG in dogs opens up access to a natural occuring animal epilepsy model in the canine population.
(1) Ives JR. New chronic EEG electrode for CCU/ICU monitoring. J. Clin. Neurophysiol. 2005;22:119-123.
(2) Ives JR and Gloor P. New sphenoidal electrode assembly to permit long-term monitoring of ambulatory patients. Electroenceph Clin Neuropohysiol 1977;42:575-580.
(3) Ives JR and Gloor P. Update: chronic sphenoidal electrode. Electroenceph Clin Neuropohysiol 1978;44:789-790. (Supported by Department of Clinical Studies, Ontario Veterinary College, University of Guelph.)