Despite the right care, a shelter can be a stressful environment for dogs. Researchers from the University of Utrecht investigated whether the amount of cortisol hormone in hair indicates the levels of stress dogs experience before, during and after their shelter stay.
There is no difference between the cortisol levels of the dogs when they enter the shelter and the control group of domestic dogs. After six weeks in the shelter, the level of cortisol in the hair seems to have increased by a third (on average from 16 pg/mg to 21.8 pg/mg). In the measures six weeks and six months after adoption, cortisol levels declined, moving in the direction of the values at admission to the shelter. The results were published in the scientific journal Scientific reports April 21, 2022.
cortisol in the hair
Cortisol, the stress hormone, accumulates in the hair, in humans but also in animals. By measuring cortisol levels in hair, researchers can get an idea of stress response and recovery over weeks or months, depending on the length of hair examined. This technique has been widely used in humans and other species, and about fifteen scientific studies have been carried out in dogs to date.
“In addition to the cortisol measurements in the hair, we also measured the cortisol values in the urine of the dogs. This gives a short-term picture while the hair measurements show the long term,” explains researcher Janneke van der Laan.
At the shelter every day
Researchers examined the hair of 52 shelter dogs at four time points: just before admission, after six weeks at the shelter, six weeks after adoption, and six months after adoption. They compared the cortisol values before admission with those of twenty domestic dogs, which were similar in terms of breed, age and sex.
Van der Laan: “We took daily measures in the shelter for more than a year. After the adoption, the new owners – after clear instructions – cut the dog’s hair and sent him to us. They were helpful and enthusiastic, and were very interested in what their dog had been through before the adoption.”
More cortisol in small dogs
A surprising result is that small dogs generally have higher cortisol levels than large dogs. “We’ve also seen this pattern in previous studies, for example in a study of the resting pattern of shelter dogs. We don’t have a clear hypothesis as to why, but it’s interesting and it’s a area of interest for future research.
Well-being in refuge
All of the shelter dogs examined were in the same shelter. Of course, there are significant differences between shelters, not only in the Netherlands but also internationally. In the Netherlands, dogs are usually kept individually, while in other countries they are often kept in groups.
“We know that a shelter is not a stress-free environment for dogs, although staff members do their best to achieve the best possible welfare,” says Van der Laan. “Even if you organize a shelter in the best possible way, there are always stressors, like crowds of other dogs and not being able to go out as often as usual. And most importantly: the dog left his old familiar dog environment.”
The shelter in this study has a pioneering role in improving the well-being of dogs: it uses glass walls instead of bars to reduce noise pollution for dogs, for example. “The fact that we measured an increased amount of cortisol even in this shelter suggests that this will also be the case in other shelters,” Van Der Laan said.
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Material provided by Utrecht University. Note: Content may be edited for style and length.