Cortisol is often used as a measure of stress in pigs. Multiple samples are often taken to see how long it is elevated and when the peak of the stress response was. Adrenal function tests are used when studying long term stressors to see if the adrenal gland has changed over time. Catheters are used to avoid raising cortisol levels when sampling the blood, though this is not always possible. An alternative could be measuring cortisol through the saliva which has proportional levels to the blood. This procedure should be non-stressful and not cause a response to the collecting. Penned pigs were sampled repeatedly for 30 minutes or over 3 hours at 30 minute intervals. Minor changes of cortisol were noted, indicating no significant stress was induced by multiple sampling. Also, sampling in a group setting did not increase the cortisol levels in the other pigs. In research barns, multiple samples of saliva can be used to assess cortisol levels.
Validation of Sampling Techniques for Assessing Stress in Pigs by Salivary Cortisol (full article)
