Cortisol levels in dog hair increase when they go into a shelter and decrease when they are adopted, showing a way to measure their long-term stress levels
21 April 2022
Measuring levels of the hormone cortisol in dog hairs can indicate how stressful living in a shelter is for the animals, and could help to improve their well-being.
“We know there are many stressors in dog shelters, which might be separation of dogs from people they are attached to, or new routines, unfamiliar smells and sounds,” says Janneke van der Laan at Utrecht University in the Netherlands.
Cortisol is produced by the adrenal glands as a response to stress in many animals, including humans and dogs. It travels around the body in the blood, causing changes – such as increased blood glucose levels – that prepare the animal to deal with the stress.
Cortisol can be locked into hair as it grows, so in more stressful conditions, higher levels of cortisol are stored in the hair. While cortisol measurements in urine or blood are sometimes used as a sign of stress at a particular time, hair cortisol levels reflect the longer-term presence of stress.
Van der Laan and her colleagues tracked hair cortisol levels in 25 dogs from when they were first put into a shelter until after they were adopted. The dogs were either given up by owners who could no longer care for them or were strays that had spent a few days on the streets.
After six weeks in the shelter, hair cortisol levels were 31 per cent higher than when they entered the shelter. After being adopted, cortisol levels fell back to pre-shelter levels within six weeks.
“Our study validates the use of hair cortisol to measure chronic stress and shows how it can be used to measure stress levels in shelter dogs,” says van der Laan.
However, cortisol can be released in response to both positive and negative events, so other measures of stress need to be considered too.
“If you only look at cortisol levels, it would give you some information, but we would argue to also look at the behaviour of the dogs and also other welfare indicators to make a complete welfare assessment,” says van der Laan.
Tracking stress levels could help people to improve living conditions for shelter dogs, she adds. “It might be interesting for welfare assessments in shelters to look at changes in hair cortisol levels, for example, when they have different management systems,” says van der Laan.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-022-09140-w
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