Recent research shows that the way you greet your dog after a short or long separation makes a huge difference to the dog. Whenever I return home, or come down the stairs after a night's sleep and encounter one or more of my dogs, I go through a bit of a greeting ritual. This involves talking to the dog (or dogs) in a happy voice using their names, and at the same time I am touching and patting them on the head and flanks. I developed this habit partly because it makes me feel good and the dogs seem to respond positively, but also because back in the 1960s and 1970s, the psychologist Harry Harlow did an extensive series of studies which showed that touching was an important part of establishing warm and affectionate bonds between individuals. He showed that the depth of love that a child has for its mother is partly due to the amount and quality of touching that the child and the mother engage in. A practical extension of his findings is that clinical psychologists who work with married couples or families are trained to observe whether or not the individuals casually touch each other during therapy sessions, since this is a positive sign which indicates that there is still a measure of affection and emotional bonding present.
Some new research which has been accepted for publication in the journal Physiology and Behavior confirms the importance of touching—this time while looking at the emotional responses of dogs when a familiar person greets them after a period of separation. Therese Rehn, Linda Handlin, Kerstin Uvnäs-Moberg and Linda J. Keeling are researchers from the Swedish University of Agricultural Sciences in Uppsala who conducted a study on 12 beagles. The general setup involved a familiar person leaving the dogs in a test area for 25 minutes and then returning. The dogs were alone in the area accompanied only by an unfamiliar veterinary student who (except when called upon to draw blood samples) sat quietly and did not interact with the dogs. We know that even though the dogs were familiar with the area in which they were left, this is potentially a stressful period of separation, and other research has shown that dogs are comforted by, and often seek the presence of, a familiar friendly person (for example see here).
When the familiar person returned after the separation, the manner in which she was supposed to greet the dog was scripted. In one condition the familiar person greeted the dog by talking to it in a friendly tone of voice and petting it. In another condition the same verbal greeting was given but the dog was not touched. Finally, in a control condition the individual did not greet the dog in any way, but simply entered the room, sat down on a chair, and began to read a magazine.
These experimenters measured the emotional response of the dogs using a technique which is becoming more common among behavioral researchers. It involves determining the amount of oxytocin released into an individual's blood stream (for example see here). The hormone oxytocin is produced in our bodies in various social situations, and it is sometimes referred to as the "love hormone" since our bodies release it at high concentrations during positive social interactions such as falling in love, experiencing an orgasm or breastfeeding. The changes in the amount of oxytocin are believed to be an indication of the positive affectionate feelings that an individual is undergoing at the moment.
In addition the researchers looked for another hormone which reflects the flip side of the coin, namely the amount of stress that the dogs were feeling. What they were also measuring was the concentration of cortisol in the blood. Cortisol is often referred to as a "stress hormone" since it appears in times of unease, fear, tension, or anxiety.
The results were rather straightforward. At the sight of the familiar person returning, the dogs became more active, with tails wagging. The sight of that familiar person was obviously a positive event since the concentration of oxytocin in the dogs' blood increased and the concentration of cortisol decreased. When the familiar individual greeted the dog using both their voice and touch, the increase in oxytocin went up to much higher levels than it did when the greeting involved just voice alone. The mirror image occurred for the cortisol levels, where the drop was sharpest when the person used both voice and touch in their greeting.
An interesting feature of the data was that the positive emotional effects persisted for a long time after the actual greeting when voice and touch used together. The positive change and emotion dissipated much more quickly when the dog was greeted only by speaking to it, and most quickly when the familiar person returned to him did not interact with the dog. In this last condition, where there was no social interaction, the dogs actually seemed bothered, and would often wander over to the unfamiliar person in the room to try to make physical contact with them.
Thus it seems that although the sight of a familiar person is a positive event for a dog, and the sound of that person's voice is better, it is actually the sensation of being touched by that person which helps to boost the level of good feeling in the dog and allows the it to carry over for much longer than just the moments when dog and loved one reunite.
For this reason I suppose that I will continue to greet my dogs by bending down to touch them even though, given my current physical state and the fact that the dogs are small, makes that action a bit painful for me. The positive emotional effect on the dogs is more important to me than the momentary aching that I get from my old arthritic bones.
Stanley Coren is the author of many books including: The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
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Rehn Therese, Handlin Linda, Uvnäs-Moberg Kerstin, Keeling Linda J., Dogs’ endocrine and behavioural responses at reunion are affected by how the human initiates contact, Physiology & Behavior (2013), doi:10.1016/j.physbeh.2013.10.009