Which of the following has NOT been observed in birds experiencing FAS in a veterinary setting?

In birds experiencing Feather-Associated Stress (FAS) in a veterinary setting, pigment loss is not a commonly observed symptom. FAS can manifest in various physical and behavioral changes, but pigment loss, which refers to the discoloration of the feathers or skin, is not typically linked to the stressors associated with this condition.

On the other hand, symptoms such as cardiac arrest, feather loss, and seizures can indeed occur in birds under stress. Cardiac arrest might arise due to severe stress responses causing significant physiological changes. Feather loss is often a direct consequence of stress, as birds may engage in destructive behaviors like feather plucking or self-mutilation. Seizures can also occur due to the extreme stress response, which may affect neurological functions. These conditions highlight the impact of stress on avian health, underscoring the importance of recognizing and mitigating stressors in a veterinary context.