Psychometric Properties of a Behavioral Sedation Scale for Green Iguanas (Iguana iguana)

This prospective, randomized, complete crossover study evaluated the psychometric properties of a behavioral sedation scale in 8 adult green iguanas (Iguana iguana) following intramuscular administration of midazolam (2 mg/kg) or saline. Each animal underwent both treatments with a washout period of 7 days. Sedation was assessed in real time using a previously described behavioral scale comprising eye opening, head height, muscle tone, handling, and body righting reflex, with total scores ranging from 1 to 14. Assessments were performed at baseline and at multiple time points up to 360 minutes postinjection. Construct validity was assessed by comparing sedation scores over times, and internal consistency was calculated using the Cronbach α coefficient. A total of 23 videos were used to evaluate intra- and interrater reliability by 2 blinded, untrained observers experienced in lizard anesthesia. Midazolam significantly increased sedation scores compared with baseline from 10 to 120 minutes postinjection (P = 0.015 to P < 0.001), and scores were higher in midazolam-treated iguanas than in controls up to 300 minutes (P = 0.007). Internal consistency was excellent (Cronbach α = 0.835). Intrarater reliability was very good for total scores (intraclass correlation coefficient > 0.98) and individual items (weighted κ > 0.80). Interrater reliability ranged from poor to very good, with wide confidence intervals (95% intraclass correlation coefficient, 0.18-0.95), and disagreement between observers exceeded 1 point in 47.8% of videos. Strong correlations were observed between real-time and video-based scores (Spearman rs ≥ 0.9). These findings indicate that the scale effectively discriminates sedation and demonstrates strong internal consistency and repeatability; however, variability between observers suggests that training may be required to optimize its clinical application.