A low dose of dexmedetomidine reduces behavioral activity and visual attention to aggressive faces in dogs.

Dexmedetomidine is widely used for sedation and alleviation of fear and anxiety in dogs, but its effects on cognitive processes are not known. We studied the effect of a low dose of dexmedetomidine on dogs' gazing behavior while they observed images of emotional facial expressions of conspecifics. Eight dogs were administered intramuscular dexmedetomidine (2.5μg/kg) and saline-placebo in a randomized cross-over design. Images of neutral and aggressive dog faces were shown on a monitor, and dogs' eye movements were recorded with an eye gaze tracker. The dogs' behavior was evaluated using three sub-scores: motivation, level of sedation and activity. Friedman test and Wilcoxon signed-rank test were used to analyze the data. The dogs were able to walk without visible ataxia after both treatments. When aggressive dog faces were shown, the observer dogs made fewer (p=0.036) and shorter (p=0.025) fixations after dexmedetomidine than placebo treatment. Furthermore, after receiving dexmedetomidine, dogs gazed less at aggressive than neutral dog ears compared with the placebo treatment (p=0.036). In behavior scores, the only significant difference between treatments was detected in activity score: dogs were less active after dexmedetomidine than placebo (p=0.026). In conclusion, a low dose of dexmedetomidine reduced dogs' sustained attention to aggressive conspecific faces, while leaving core face-scanning strategies and cognitive engagement intact. These findings provide objective support for dexmedetomidine's anxiolytic profile and indicate that eye-tracking is a sensitive tool for assessing how pharmacological treatments influence socio-emotional attention in dogs.