Key Findings
Researchers studied how living alone or with another dog affected the behaviour and stress levels of shelter dogs by collecting information about the dogs’ behaviour and urine samples to measure their stress levels.
Dogs living alone were more likely to be stressed, as shown by their behaviours like licking their lips, whining, and flattening their ears. While the difference wasn’t statistically significant, dogs living together were generally less stressed at the end of the one-week assessment period.
Dogs living together were adopted four days earlier on average than dogs living alone. The study also found that for every 10 kg increase in a dog’s weight, it stayed in the shelter for one more day.
Summary
While single-housing in shelters helps prevent disease and injuries, it can also cause stress for dogs. Studies have shown that social interaction with other dogs can reduce stress and improve their well-being. There are conflicting findings about whether pairing dogs together is beneficial.
The study “Effects of single- or pair-housing on the welfare of shelter dogs: Behavioural and physiological indicators” focused on the short-term impact of pairing dogs together. Researchers observed the behaviour and stress levels of dogs housed alone and in pairs for seven days.
Study Set Up
The researchers conducted the study in the United States, at the Humane Society of Western Montana in Missoula, Montana, in December 2017 and May 2018. Half of the dogs were enrolled in December, and the other half were enrolled in May.
Study Subjects, Selection and Housing Procedures
To be eligible for the study, dogs had to be at least six months old and pass the Match Up II dog-dog test, an evaluation protocol designed to help shelters get a better understanding of the personality of their dogs. The test involved walking two dogs — based on staff recommendations and matched in size — past each other on leashes. Dogs that exhibited aggressive behaviour, such as growling, snapping, or showing teeth, were excluded. Dogs that showed fear but recovered within 30 seconds were considered eligible. A total of 61 dogs were enrolled.
After passing the test, dogs were randomly assigned to either single-housing or pair-housing. Pair-housed dogs were matched with companions based on their size, energy level, and breed type. The goal was to create balanced groups in terms of breed type and size, which are factors that influence adoption rates. The housing arrangements were intended to remain consistent throughout the study, but changes could occur if a kennelmate was adopted.
Data Collection Procedures
Behavioural
The day after the sociability test, researchers started recording four one-minute videos of each dog each day to study their behaviours. The first video showed the dog’s reaction to a human standing in front of its kennel. The other three videos were remotely recorded by cameras at different times of the day, both when the shelter was open and closed. This allowed researchers to observe the dogs’ behaviour without human interference.
Researchers studied the dogs’ behaviour by identifying and recording 63 different actions. Some behaviours were seen in all dogs, while others were only observed in dogs living with a companion. The researchers noted the dogs’ actions every five seconds. To ensure accuracy, another person checked 15% of the videos. Only behaviours that occurred in more than 5% of the videos were included in the final analysis. This meant that 36 behaviours were not considered.
Cortisol:creatinine (C:C) Levels (Stress Levels)
A group of dogs (22 living alone and 18 living with another dog) had their urine collected every day for seven days. The first sample was taken before the dogs were placed in their new homes. This helped researchers measure the dogs’ stress levels, using the cortisol hormone level as an indicator, and how they responded to their new living conditions. They compared the stress levels on each day to the initial level.
Length of Stay
To find out how living alone or with another dog affected the dogs’ chances of being adopted, the researchers calculated how long each dog stayed in the shelter. They only included dogs that were adopted and had not been in the shelter for more than one day before the study started. They also excluded dogs that were moved from one housing type to another or placed in foster care. This meant that 27 dogs were not included in this part of the study.
Follow-up Evaluation
Two weeks after the initial Match Up II assessment, the remaining eight dogs were tested again. The tests were the same as the first one.
Study Results
Incidents
During the study, two pairs of dogs were separated because they fought. Wilson, Gracie, and Max were moved to live alone. Lucy was paired with another dog named Devin and stayed in the study. In total, there were 30 dogs living alone and 31 dogs living with another dog. All of the fights happened within 36 hours of the dogs being put together, and no one was hurt.
Behavioural Analysis
Researchers recorded 1,662 one-minute videos of the 61 dogs. They found that dogs living alone were more likely to show signs of stress, such as licking their lips, whining, and flattening their ears. This suggests that dogs living with another dog were less stressed, which is similar to what other studies have found.
The dogs were more likely to whine on the first day, probably because they were stressed about being in a new place. This is supported by the higher stress hormone levels measured on that day. However, the dogs’ ears flattening slightly over time was unexpected, as they usually get used to the shelter by the fourth day. This might mean that they were still stressed, even though they were whining less. On the other hand, the dogs didn’t often show repetitive or fearful behaviours, probably because the shelter provided them with things to do, like playing with people and toys.
The researchers also found that dogs living alone engaged more in single-object play, stood on their kennels, and gazed around more than dogs in group housing. This might be because dogs living alone didn’t have as much to do, while dogs living together could play with each other. It seems like the dogs living alone were looking for something to do outside their kennels.
Stress Level Analysis
Researchers collected urine samples from 22 dogs living alone and 18 dogs living with another dog for eight days. They found that only two factors — the dog’s sex and how the dog entered the shelter — affected their stress levels.
In particular, dogs that were given up by their owners were more stressed than dogs that were brought from other places. This is similar to what other studies have found. The dogs that were brought from other places, mostly by plane or car, had lower stress levels. This might be because the stress of being transported was greater than the stress of being in the shelter. This highlights how a dog’s past experiences can affect how stressed they are now.
In comparing singly-housed dogs and paired dogs, both groups of dogs had higher stress levels on the first day, probably because they were stressed about being moved to new kennels. Over the week after the move, the researchers found that dogs living with another dog had a bigger decrease in stress levels than dogs living alone on most days, except for the first day. The biggest difference in stress levels between dogs living alone and dogs living together was seen on the seventh day.
However, researchers cautioned that the difference noted is not significantly different enough to warrant a conclusion that group housing is able to lower cortisol hormone levels. A longer experimental period might be needed to reveal significant differences between the two groups. Still, this finding is important for shelters because moving dogs to different kennels often can cause mild stress.
Length of Stay and Sociability
Dogs that lived with another dog were adopted an average of four days sooner than dogs that lived alone. This might be because people looking for a dog often already have a dog or want to do social activities with their new dog. So, they might prefer a dog that gets along well with other dogs. The study also found that for every 10 kg increase in a dog’s weight, their length of stay increased by one day. This echoes previous research that showed larger dogs took longer to be adopted than smaller dogs.
Although the study didn’t find any significant changes in the dogs’ social skills, it’s important to be careful about drawing general conclusions from this. Few dogs stayed in the shelter long enough for the researchers to test them again after two weeks, and none stayed long enough for a four-week test. This makes it hard to know if the dogs’ social skills will change over a longer period. Also, the shelter provided the dogs with plenty of enrichment, such as playing with other dogs in a fenced area. In shelters that don’t offer these activities, living together might have a bigger impact on the dogs’ social skills.
Miscellaneous
Data From Study:
–
Year of Publication:
2024
External Link:
Hecker G, Martineau K, Scheskie M, Hammerslough R, Feuerbacher EN (2024) Effects of single- or pair-housing on the welfare of shelter dogs: Behavioral and physiological indicators. PLoS ONE 19(6): e0301137.
https://doi.org/10.1371/journal.pone.0301137