Medetomidine hydrochloride

For general anesthesia, 0.04 mg/kg of medetomidine hydrochloride (Domitor^®, Zoetis, Espoo, Finland) was injected intravenously, and 5 mg/kg of ketamine hydrochloride (Yuhan, Seoul, Korea) was injected intramuscularly. A customized instrument was developed with a 1 mL syringe and a PTFE Teflon tube with 0.5 mm inner diameter and 0.9 mm outer diameter (Uxcell, Hong Kong, China) (Figure 1). Waterproof tattoo ink (Tana Lee Temporary Coloring Tattoo Ink, Oyecoskorea, Incheon, Korea) was used. Using a video otoscope (Karl Storz Veterinary Endoscopy America, Goleta, CA, USA), an ink droplet was placed on the posterior quadrant of the pars tensa (PT). The day the ink drop settled on the TM was considered Day 0. The TM was re-evaluated by filming with the AIDA-vet video capture system (Karl Storz Veterinary Endoscopy America, Goleta, USA). Images showing the width of the malleus and the whole PT were captured. Ink drops were evaluated on Days 3 ± 1, 7 ± 1, and 14 ± 1, until either day 21 ± 1 or until the ink deviated from the PT. The image from day 0 was visualized on a laptop computer screen during re-evaluation [6 (link)]. Each beagle TM was divided into a control group or a treatment group. No substance was applied to the control group, while the treatment group had 0.05 mL of cAD-MSCCM applied directly on the TM every week using video otoscopy.

CT and MRI of the brain were performed under general anesthesia with at least 5-day intervals in random order. After fasting the dog for at least 8 h, a 24-gauge catheter was aseptically placed into a cephalic vein. Anesthesia was induced with intravenous injection of 10–15 μg/kg of medetomidine hydrochloride (Domitor, Zoetis, Finland) and 2 mg/kg of alfaxalone (Alfaxan, Jurox Pty Ltd., Australia). Following endotracheal intubation, anesthesia was maintained with isoflurane (2–4%; Ifran, Hana Pharm, South Korea) delivered in 100% oxygen (1–2 L/min). During the induction and maintenance of anesthesia, heart rate and oxygen saturation were continuously monitored with a respiratory sensor, electrocardiography (ECG) tracing, and pulse oximetry. Following the MRI and CT scans, the overall condition of each dog and any anesthesia-related side effects, including vomiting, depression, and anorexia, were monitored for a duration of 5 days.