17 April 2018

Is Scent Enriching for Shelter Dogs?

Research investigates the effects of enrichment using the scent of coconut, vanilla, ginger and valerian.

Dogs have excellent noses, like this one belonging to a Shih Tzu dog. Researchers tested the effects of scent enrichment on shelter dogs and found  it reduced signs of stress.
Photo: chaoss/Shutterstock

Animal shelters are stressful environments for dogs, and so anything that helps them to be less stressed is beneficial. Scientists from Hartpury University Centre tested the effects of presenting scent-infused cloths to shelter dogs. The results are promising and suggest scent enrichment may work well for shelter dogs.

Study authors, John Binks and Dr Tamara Montrose, say
“In our study we found that shelter dogs showed reduced vocalisations and movement when exposed to cloths scented with ginger, coconut, vanilla and valerian. In addition, we found that dogs exposed to coconut and ginger slept more. Since excessive vocalisations and activity may indicate stress in kennelled dogs, as well as being behaviours that can be found undesirable by potential adopters, our study suggests that these odours may have application in rescue shelters to reduce stress and enhance adoption.”

Enrichment means adding things to the animal’s environment that are designed to improve welfare, for example by allowing the animal to engage in species-specific behaviour, encourage use of the environment, get more exercise, encourage learning, and decrease boredom and abnormal behaviour. Since shelter dogs spend a large part of their day in kennels, enrichment is important to improve their welfare.


Dogs have impressive noses (and vomeronasal organs) and, as we all know, they spend a lot of time smelling things. The scientists say enrichment works best if it targets an animal’s primary sense, so it is surprising there isn’t more research into scent enrichment for shelter dogs.

The experiment used the smells of coconut, vanilla, ginger and valerian because they are safe for dogs, easily available, and have been found to be beneficial for other animals, such as wombats, sea-lions, Javan gibbons, cats and rats (read about different scents that cats like).

15 dogs took part at a shelter in Gloucestershire, England. Most were medium-sized dogs and two were small.

The dogs were presented with scent on a cloth put in their kennel for a few hours per day. There were two control conditions: an unscented cloth (to provide a comparison for the different smells), and no cloth (to control for the effects of the presence of a new item). The unscented cloth control condition took place before the presentations of smells, and the no cloth condition took place after.

Each condition took place over three days, with a two day gap between them.

Cloths were prepared an hour in advance by adding a few drops of essential oils or fragrance oils, and then kept in a ziplock bag until they were used. The experimenter wore gloves to ensure they did not accidentally transfer any other scents to the cloths. Dogs were given half an hour to get used to the item, and then observed for a two-hour period, the latter half of which was during the shelter’s opening hours for visitors. This was in the middle of the day when feeding and exercise did not happen, so the dogs' behaviour would not be affected by waiting for the next meal.

When the scented cloths were present, dogs vocalized less. Since barking, whining etc. can be signs of stress, this suggests they were less stressed. Dogs also spent more time resting and less time moving when the scents were present. For the ginger and coconut scents, dogs spent more time sleeping.

These results suggest the scent enrichment helped the dogs be less stressed.

There was also an effect of time, in that when the shelter was open to visitors, dogs vocalized more, stood more, and spent less time resting. They were also at the front of their kennel more.

The scents were always presented in the same order. This was so that other dogs taking part would not have their scent contaminated by one of the other smells wafting in to the kennel. This means there is potential for an order effect. However, because the dogs were presented with the controls before and after the different scent conditions, it does seem that the results are due to the scents.

The scent enrichment used in this study would be easy to use at a shelter, although more research is needed with a larger number of dogs. The results are very promising, and suggest the use of these scents can help shelter dogs to be less stressed.


You can follow Dr. Tamara Montrose, one of the authors of the study, on twitter.

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Reference
Binks, J., Taylor, S., Wills, A., & Montrose, V. T. (2018). The behavioural effects of olfactory stimulation on dogs at a rescue shelter. Applied Animal Behaviour Science.

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