Effective Dose 50 of Intranasal Lorazepam for Clinical Sedation in Zebra Finches (Taeniopygia guttata).

Sedation is a common procedure in avian practice and benzodiazepines are often used as sole agents or in combination with other drugs to sedate avian patients. Midazolam and diazepam have been evaluated in zebra finches (Taeniopygia guttata); however, lorazepam has not. Our aim was to determine the sedation effective dose 50 (ED50) of intranasal (NAS) lorazepam in zebra finches. Using the Dixon up-and-down method, the first randomly selected finch received 0.25 mg/kg NAS lorazepam. Sedation was scored after 20 minutes: 1) recumbent = 0 versus not recumbent = 1; 2) captured at first attempt = 0 versus not captured at first attempt = 1; 3) absence of righting reflex within 2 seconds = 0 versus righting reflex within 2 seconds = 1. Total sedation score was calculated by adding the 3 parameters; birds were classified as sedated if scored ≤1 and as not sedated if scored ≥2. Based on the first bird's classification, the next random bird received an increase (if preceding bird was not sedated) or deduction (if preceding bird was sedated) by a factor of 2. Crossover events (contradictive responses between 2 sequential animals) were noted. A total of 15 animals (5 males, 10 females), weighing 12.16-18.80 g, were used. A total of 6 crossover events were identified. The highest and the lowest dose administered were 1 and 0.0625 mg/kg, respectively. Lorazepam NAS ED50 was 0.3 mg/kg by the Dixon up-and-down method. No morbidity or mortality was noted, and all birds recovered uneventfully. Future studies evaluating this sedation protocol are needed to further determine the practical clinical value of lorazepam as a sedative drug in passerine species.