Ijichi, C., Green, S., Squibb, K. et al. 2019. Zylkéne to load? The effects of alpha-casozepine on compliance and coping in horses during loading. Journal of Veterinary Behavior 30, 80-87.

Horses are routinely transported for access to safe off-road riding, veterinary care, breeding, sale, or moving to a new home environment. However, transport is a known stressor in horses. For this reason, problem behavior when loading is a commonly reported issue, which presents risks to handlers and horse welfare. Existing literature and manufacturers' recommendations suggests that alpha-casozepine may be effective in improving the behavior and welfare of horses during loading onto a vehicle for transport. The present article aims to assess the behavioral and physiological effects of a commercially available alpha-casozepine feed supplement (Zylkéne Equine) in horses during loading and confinement on a transport lorry. Subjects (n = 10) were loaded once with the supplement and once without, in a balanced random order with each subject acted as their own control. The handler was blind to treatment. Time to load onto the lorry, and movement of feet, licking and chewing, and vocalizing within the lorry were recorded as behavioral indicators of compliance and coping. Heart rate, heart rate variability, salivary cortisol, and infrared thermography of both core temperature and the discrepancy between eyes, were measured as indicators of arousal. There were no significant differences in physiology between treatment and control (P > 0.05). Treatment resulted in a significantly shorter loading time than control (P = 0.04); however, the actual difference in median time was only 0.45 seconds. No other behavioral indicator differed between treatment and control (P > 0.05). Power analysis revealed the sample was sufficient to detect a significant effect. Where modest effects were observed for a small number of variables, treatment effect contradicted predictions. Taken together, this indicates that alpha-casozepine does not affect a horse's ability to cope with loading and confinement in a horse lorry. Further work is required to ascertain whether the maximum dosage—twice that used here—might affect coping and behavior in horses.

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