A hands-on approach to pain

We can all think of some event in the past that has really impacted what kind of person we are today. Our past can shape us. This also holds true for how we experience pain.

Previous experience, be they stressful events or even painful ones, have a physiological effect on our brain and pain-processing pathways. This is, in part, because we are born with immature brains. Not ‘laughing at fart jokes’ immature, but developmentally immature, meaning that early experiences shape the development of our brains and bodies.

Not all animals are born like this though. Many animals, including many farm animals, are born with relatively mature brains. Can early experiences also shape how their later perception of pain?

We’d want to know this because farm animals routinely undergo painful husbandry procedures (like getting their tails cut off, castration, de-horning). Before these husbandry procedures occur, young farm animals have already experienced a host of events (like being helped during birth or being moved from yard to yard) that might influence how they later experience pain. We want to make sure that these early experiences aren’t making them more sensitive to pain, or ideally, that we could somehow make them less sensitive to pain so they find these procedures less distressing.

I’ve begun to answer this question by looking at how early human handling affects later pain sensitivity of lambs (who are one of those animals that is born relatively mature). I compared the behavioural responses (i.e. how much lambs act ‘pained’) of handled lambs and non-handled lambs to getting their tails cut off. Handled lambs actually acted less pained than non-handled lambs, meaning that something about the handling procedure changed how they experienced pain. It’s likely that the actual tactile/touching aspect of it made the difference. This is because there were also lambs that were nearby who saw/heard the handling treatment without experiencing it themselves, and they showed no difference in their pain response from those lambs that had no contact with the treatment at all.

This means that any moving around or handling we do of lambs early in life doesn’t have any detrimental effect on their perception of pain (it may even make them less sensitive!). But, it also means that lambs aren’t as ‘unchangeable’ as we thought. Early experiences may still be able to shape their development. The question then is, what other experiences (painful ones?) may also alter how lambs perceive pain?

Reference: Guesgen, M.J., Beausoleil, N.J., Stewart, M. (2013). Effects of handling and human presence on pain sensitivity of young lambs. Veterinary Anaesthesia and Analgesia 40, 55-62.