Effects of medetomidine and medetomidine-butorphanol on transcranial color-coded duplex ultrasonography in healthy dogs.

The study was designed to determine the effects of two protocols of sedation, medetomidine and medetomidine-butorphanol, on cerebral blood flow (CBF) by transcranial color-coded Duplex ultrasonography in healthy dogs. Transcranial Doppler ultrasonographic examination was performed in 20 dogs before and 20 min after sedation with either medetomidine (group 1) or medetomidine-butorphanol (group 2). The left and right middle cerebral arteries (LMCA and RMCA) were evaluated using the temporal windows, and the basilar artery (BA) was studied through the suboccipital window. Peak systolic velocity (PSV), mean velocity (MV), end diastolic velocity (EDV), resistance index (RI), and pulsatility index (PI) were measured for each vessel. Blood pressure (BP) and heart rate (HR) were also recorded before and after sedation in both groups. Statistically significant differences were found for PSV, MV and EDV when RMCA and LMCA were interrogated before and after sedation. PSV, RI and PI were found to be statistically significantly different when the study was performed on the BA. These results should be taken in account when a transcranial Doppler is performed in dogs sedated with the mentioned protocols and it might suggest some degree of neuroprotection.