Electroencephalographic Recordings in the Canine: Effects of Low Dose Medetomidine or Dexmedetomidine Followed by Atipamezole

Objectives: 1) To describe electroencephalogram (EEG) appearance in the awake dog and compare these results with EEG recordings after low dose medetomidine (2 μg/kg IV) followed by atipamezole (10 μg/kg, IM); 2) To institute EEG recordings after low dose medetomidine or dexmedetomidine as a standard of practice if focal abnormalities and amplitudes were not significantly altered by pharmaceuticals in Phase 1 of this study. Methods: Electroencephalograms were performed on eight clinical canine patients with suspected intracranial disease involving the prosencephalon. A five lead montage was used to record the EEGs. Each dog had an awake, baseline recording followed by an EEG performed after administration of low dose medetomidine (2 μg/kg IV) then atipamezole (10 μg/kg, IM). In the second phase of this study, the same dose of medetomidine or dexmedetomidine at 1 μg/kg IV and atipamezole (10 μg/kg, IM) were used in the evaluation of 20 clinical patients with suspected neurologic disease. Results: In Phase 1, awake recordings were laced with movement artifacts. After medetomidine and atipamezole, EEG waveforms were slower. Following atipamezole, however, the frequencies were observed to increase with time. Statistical evaluation revealed significantly more artifacts in baseline recordings. No statistically significant change was observed in focal abnormalities or amplitude. In Phase 2, the a2-adrenoreceptor agonists followed by atipamezole without the use of lidocaine produced clinically reliable results. Clinical Significance: Quality and diagnostic electroencephalogram (EEG) recordings are frequently inconvenient to obtain in the awake dog. Movement results in artifacts and dislodged leads. Administration of low dose medetomidine or dexmedetomidine followed by atipamezole reliably reduced the impact of movement artifacts and produced clinically valid EEG recordings in dogs.