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In the same way that there are personality and emotional response changes that occur with age in people, there are similar changes in dogs. Even such basic responses, such as how we direct our attention, change in both humans and canines as they age (click here for an example). However, sometimes these changes, although important, are not readily visible but take some complicated measurement techniques to detect. I was reminded of this recently when I was at a dog show watching the obedience rings. The ring in front of me contained seven older dogs who were competing in the veteran's class (for dogs aged 7 years and older). They were all were doing the long down exercise with the handlers 40 feet away across the ring. The ring next to it contained a group of novice dogs who were doing the long sit exercise with their handlers also across the ring. These group exercises are always stressful for the dogs because they are in an unfamiliar setting and their owners seem to be too far away from them to be a reassuring presence. Suddenly, there was a loud crashing sound caused by a stack of folding chairs toppling off of a cart, which was being used to move them. Several of the novice dogs broke from their sit position and two began to bark, while all of the veteran dogs remained where they were, seemingly totally unmoved by the unexpected noise. The person standing next to me observed the situation and commented, "Well those old guys seem to be a lot more secure and unemotional than the younger dogs."
I was not so sure about the accuracy of her observation. Although none of the older dogs broke from their down position, two of them gave obvious stress yawns, another two of them began to pant in what looked like a suppressed stress response, and yet another one pushed his head down onto his paws as if he was trying to make himself appear to be smaller (often a fear response). It was then that I remembered a study that looked at the differences in the emotional responses between adult and senior dogs when their owners were not close enough to provide them with comfort and support.
This study was conducted by researchers at the University of Padua. The team was headed by Paolo Mongillo of the Laboratory of Applied Ethology and was published in the journal Physiology and Behavior*. It uses a variation of what is known as the Strange Situation Test. This is a procedure devised by Mary Ainsworth in the 1970s to observe the emotional responses and the attachment relationships between children and their caregivers (usually their parents). The situation involves a small, relatively barren room, with a couple of chairs in it. There is a fixed scenario of events in which the child is brought into the room by its caregiver, a stranger enters the room and tries to interact with the child, then the caregiver leaves, and sometimes, shortly afterward, the stranger then leaves (leaving the child alone in the room), and then after a brief interval the caregiver returns. The interactions are videotaped and scored, and the child's reactions to being in an unfamiliar place with unfamiliar people or alone are recorded. In general it is observed that in such potentially stressful interactions the normal well-attached child treats their caregiver as a "safe haven" and seems to gain confidence and security by having their caregiver close by. These same kind of responses have been observed in dogs using a variation of this test (click here for an example).
In this more recent study, 50 dogs were tested. Half of the dogs could be classified as adults (average age 4.4 years) and half as aged or senior dogs (with an average age 9.6 years). Analysis of videotapes of the dogs in this somewhat distressing situation showed that the older dogs seemed to seek out physical contact with their owners more at the beginning, but afterward they acted much more passively toward the stranger and what was going on around them than the younger adult dogs. The senior dogs did not seek out social interactions as much, nor did they tend to act in an apparently worried manner by standing near the door that their owner disappeared through, whimpering, etc. Both the adult and the senior dogs clearly showed that they were emotionally attached to their owners and both age groups apparently felt more secure when their caregiver was in the room. However, other than the small differences I mentioned just above, there was little obvious difference in their behaviors.
Nonetheless, it turns out that there were large emotional differences present, but it just takes a more sophisticated set of measurements to demonstrate this. Prior to starting the Strange Situation Test, samples of saliva were taken from each dog, and then another sample was taken shortly after the end of the test. These were compared to samples taken when the dog was at home in a familiar, non-stressful, setting. The saliva was then analyzed for the presence of cortisol which is a stress-related hormone. Although there was little difference in the observable behaviors of the senior and adult dogs, it turns out that the older animals had significantly more cortisol in their system indicating that they were under a higher degree of stress than their more youthful counterparts.
The authors summarize their results by saying, "Thus, while passive behavior increases as dogs age, it does not seem to guarantee that they cope better with social separation." How does that conclusion square with the fact that the older dogs seemed to lie quietly and un-responsively during the stress inducing laboratory test, in much the way that the senior dogs in the veteran' s class that I observed seemed to be less bothered and less reactive to events that apparently disturbed the younger dogs in the ring next to them? These researchers explain this by saying "inhibiting outward signs does not mean successfully regulating emotions, and the passiveness observed during the test is more probably active suppression of behavioral signs than a relaxed reaction to social challenges." In other words, although older dogs may have more pronounced emotional responses in stressful situations (as measured by the increased presence of stress hormones evoked by a strange situation, unfamiliar people nearby, and their separation from their owners) they have learned to control their behaviors to a better degree. They are not going to overtly act out and display behaviors that indicate that they are distressed to the same degree that they did when they were younger.
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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* Data from: Paolo Mongillo, Elisa Pitteri, Paolo Carnier, Gianfranco Gabai, Serena Adamelli, Lieta Marinelli (2013). Does the attachment system towards owners change in aged dogs? Physiology and Behavior, 120, 64 – 69.
