We now know why some dogs display aggressive behaviour

Credit: skeeze / Pixabay

We often hear about violent dog attacks, especially on young children, which cause their victims severe or fatal injuries. These aggressive dogs which are often bull terriers or rottweilers end up being put down due to their violent and uncontrollable behaviour.  But how can we prevent deaths related to dog attacks from happening in the future?   Firstly it is important to try and understand the reasons behind these dogs’ violent nature.  Scientists believe it comes down to a hormonal imbalance. 

Until now very few scientific studies have looked into a hormonal cause as the reason behind a dog’s aggressive behaviour, with only testosterone and serotonin suggested as potential hormonal  factors.  However a new research study led by Evan MacLean from the University of Arizona looks at imbalances in a dog’s hormonal system as a factor.   According to Mr MacLean and his team, oxytocin and vasopressin are the real hormones that influence dog’s social behaviour!

Oxytocin, also known as “the happiness hormone“, is a hormone involved in childbirth, breastfeeding, sexuality and social interactions. A strong increase of oxytocin can be seen in people who have just been kissed or hugged. Conversely, vasopressin (which is a hormone that regulates water retention) has been identified as responsible for a certain aggressiveness in humans.

Dog's aggressive behaviour
Credits : wernerdetjen/Pixabay

When carrying out this research study, scientists selected several pairs of dogs of the same age, sex and race.  The only difference was their behavioural differences: one of the dogs was aggressive while the other was not. By measuring levels of ocytocin and vasopressin before and after having carried out different every day situations, Mr MacLean and his team drew a link between hormone levels and the dog’s behaviour.

Like humans, dogs showing aggressive behaviour when in the company of dogs or other individuals had a much higher level of vasopressin.  On the other hand, no difference in ocytocin levels was observed in the dogs during the experiment.  However when comparing oxytocin levels with the dogs in the experiment and guide dogs which have been raised to be as calm as possible when confronted with any situation, it showed these trained dogs had higher levels of this hormone. When comparing the ratio between oxytocin and vasopressin levels,  it appears that oxytocin inhibits an aggressive nature in some dogs.

These discoveries could help create new treatments regulating the rate of vasopressin in the blood of some dogs.  These treatments which are already being carried out in humans could be a big step forward in helping to control aggressive behaviour in certain dogs.  However we shouldn’t forget that although aggressiveness is simulated by an imbalance in the hormonal system, more often than not dogs display a violent nature as a result of a severe trauma.


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