A friend of our’s vet diagnosed their dog with a compulsive behavioural disorder for chasing his tail non-stop. The questions is: Why do dogs develop this disorder?
Animals only continue to perform a behaviour over and over if it makes them feel good. We humans do exactly the same thing. If you do something and it makes you feel good, you are more likely to do it again, whereas if you do something that makes you feel awful, you are less inclined to do it again.
So, with these stereotypical or repetitive behaviours, there has to be something happening to make the animal enjoy doing them, even if they actually cause him injury. The culprits are two neurotransmitters that are released into the brain – dopamine and opioids. Dopamine is responsible for, among other things, influencing the brain’s pleasure centre, so simply put, a flood of dopamine makes you feel good. Opioids make you feel happy, and they reduce pain, so animals who self-mutilate have a higher pain threshold.
Wendy Wilson, behaviourist