Assessment of acute stress in alpacas (Vicugna pacos): A pilot study using salivary cortisol and infrared thermography

Alpacas are an increasingly popular hobby species in Europe, characterized by specific requirements and high sensitivity to stress-related factors. Therefore, it is essential to identify which situations or factors trigger stress responses and to apply appropriate, minimally invasive sampling methods for this purpose. A viable approach involves saliva sampling using specialized collection kits, which require minimal animal restraint and handling or the use of thermographic imaging to monitor changes in body surface temperature. In both cases, data and sample collection are non-invasive, without causing pain or compromising physical integrity of the animal. No significant increase in salivary cortisol concentration ( P > 0.05) was observed in eight alpacas before and after veterinary examination. This result may be influenced by the fact that the animals were not habituated to saliva sampling, and the initial collection itself may have induced a stress response, leading to cortisol release even prior to the veterinary procedure. Consequently, the veterinary intervention did not result in a further increase in cortisol levels. The mean salivary cortisol concentrations before and after examination were 3,822.57 ± 698.32 pg/ml and 4,064.60 ± 1,217.55 pg/ml, respectively, with no significant difference ( P > 0.05). The finding that capture alone acts as a significant stressor for alpacas is further supported by a significant increase ( P < 0.05) in the surface temperature of the inner corner of the eye. The temperature measured remotely (36.35 ± 0.91 °C) increased significantly following capture during the veterinary examination (37.56 ± 1.36 °C). Our findings support the potential use of infrared thermography as a sensitive, non-invasive stress indicator in alpacas.