Cortisol could impact your dog’s behavior
For dogs, good training and responsible ownership impact their behavior, but their life experiences and genetics can also affect their temperament. Hormones may also play a role and could offer a new way to assess our canine companions. In a small study published today in the journal PLOS One, Well-behaved dogs generally had lower levels of cortisol – an important stress hormone – and higher levels of serotonin, a neurotransmitter associated with happiness.
A team from Kyungpook National University in Degu, South Korea, studied 24 dogs of different breeds, including beagles, border collies and mixed breed dogs. They used a version of the Wesen test, an assessment that typically helps determine whether an animal is better suited as a pet or a working dog. In this particular study, a human observer observed the dog’s reaction to several situations and interactions with people and other dogs. For example, the observer focused on how relaxed or anxious a dog seemed when alone and then in the presence of a complete stranger. In another situation, the team assessed the dog’s attention, confidence, fear, interest and relaxation during the Wesen test.
Some worry that the Wesen test is too subjective, because it is based on an observer’s opinion. To look for more physical evidence, the team took saliva samples and measured cortisol and serotonin levels. In animals, cortisol is released after “fight or flight” hormones like adrenaline to help keep the body alert. It also helps regulate metabolism and blood sugar. Serotonin is a neurotransmitter that carries chemical messages between nerve cells in the brain and the rest of the body. It helps support several bodily functions, including mood, sleep, digestion, and bone health. Previous studies in dogs linked lower levels of cortisol and higher levels of serotonin to less aggressive behavior.
For these dogs, salivary cortisol samples were collected before and after the Wesen test. Those who scored higher on good behaviors tended to have lower cortisol levels. These high-scoring dogs also showed less of an increase in stress hormone levels after undergoing the tests.
Sixteen of the 24 dogs had their salivary serotonin levels measured, but the results were not significant. However, dogs that scored higher had higher serotonin levels before the test than dogs that scored lower.
Since this is such a small sample of dogs, the team cautions that it doesn’t show that hormone levels necessarily cause good or bad behaviors in dogs. This provides possible evidence that examining hormones and neurotransmitters may be a more objective way to measure a dog’s temperament than assessments such as the Wesen test alone.
“Our study shows that physiological concentrations of hormones and neurotransmitters can serve as biomarkers of canine temperament,” the team writes. “These findings could help identify dogs suitable for specific working roles, such as military, police, guide or therapy dogs, and help make more informed decisions about pet dog adoption.”
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