Is it Possible to Measure the Pain Being Experienced By an Animal, By Measuring Catecholamines and Cortisol?

Question

Stress Level?

Answer 1

The simple answer is NO.  The best way to quantify pain experienced by an animal is by using specific behavioral tests that have been verified as to construct validity, face validity, etc.  One that comes to mind is the tail flick test used commonly in pain research.

Answer 2

Cortisol we can measure, which does correlate in some sense to stress. Problem is, in a labratory setting the procedures necessary to gather said stress information, would be pretty stressful - needles and cutting.

So the best way to measure stress in an animal is through behavior, comparing how it acts to how a 'normal' individual acts.

Also, keep in mind, pain is very subjective and doesn't seem to correspond to any physiological chemical we can measure. What is painful to one person may be mildly irritating to another, or reduce another to a screaming heap. How you experience a pinprick to the finger has very little do to how painful someone else perceives it.