I recently ran into a blonde woman who I occasionally see walking her two Golden Retrievers in my neighborhood. I was always amused by the way that her hair color was so similar to that of her two dogs. On this day, however, she only had the younger dog, "Silky", with her. I stopped to chat and asked about where the older dog, "Toby", was. She sighed, and then said, "Toby died last week. He had just celebrated his 14th birthday a couple of months ago so he had a pretty good run at life. Still, he was such a happy and easy-going dog that I thought that he would live forever."
As I thought about our conversation later, it dawned upon me that this was an odd thing for her to say. Yet, if we were talking about a human being, and someone said, "He had so much fear and anxiety in his life that it is not surprising that he died so young," this would be completely understandable from a psychological point of view. It is well known that anxieties cause a rise in stress hormones, such as the corticosteroids, and these hormones can negatively impact the immune system. A compromised immune system makes people susceptible to a variety of infectious diseases. These same stress-related chemicals can also affect the cardiovascular system making people much more likely targets for heart attacks and strokes. Thus in humans it is clear that those who live a happy, stress-free life can in fact expect to live longer. So given the evidence about the relationship between stress and health what my acquaintance was saying did make sense. Still, the scientist in me wanted to know if any research and been done which showed whether levels of fear and anxiety affected the health and life span of dogs in the same way as it affects humans.
It turns out that there has been some research in this area and one of the more recent studies was published in the journal Applied Animal Behaviour Science* by Nancy Dreschel of the Department of Dairy and Animal Science at Pennsylvania State University. She recruited people who had owned dogs that had died within the last five years. This was done by posting flyers at veterinary offices and various public places such as pet-related organizations, grocery stores, restaurants and so on. Those people who agreed to participate in the study had to fill out a fairly long questionnaire containing 99 items. In the end she had data on 721 deceased dogs, covering a broad range of different purebred and mixed breed animals.
Almost all of these dogs were pet dogs that had been obtained for companionship, and these were well cared for animals. Most (89%) had received some formal training at home or at a class for general obedience, and most of the owners felt that their dogs were very well trained, responded quickly to commands and never caused any problems. The average age of death for this group was 11.6 years and the most common cause of death was cancer (affecting 38% of the dogs in this study). These findings are similar to those found in other research (click here for an example). One interesting discovery in this research is one which bears on another frequently debated issue. This study found that neutered dogs had significantly longer lifespans. These data show that neutered dogs live an average of 2.3 years longer than their unneutered counterparts.
This current investigation used some complex statistics involving regression analyses so I will simplify our discussion by sticking to some of the highlights of the findings. Some of the measures are rather indirect, since they involve taking out the effect of physical factors which are already known to impact on a dog's life span, such as its size and weight.
Let's now take a look at the effects that behavioral and emotional factors have on the health of dogs. One of the more interesting questions that was asked had to do with "how well-behaved" people thought their dogs were. Remember most of these dogs had some obedience training, and most responded well to commands. So why ask the question about how well-behaved the dogs were? Other research has shown that the more anxious and fearful dogs are the more likely their owners are to describe the dogs as "not well-behaved", so a question like this will tend to reflect on the dog's general emotional state rather than its obedience. The interesting result here is that the more well-behaved the dogs are described as being, the longer their life span was found to be. The author suggests that, "Well-behaved dogs may live longer because they may be under less stress, living in a more harmonious household." A much more direct measure of fear and anxiety comes from questions about how dogs respond in the presence of strangers. The amount of stranger-directed fear that the dog commonly experienced was a strong predictor of longevity. Specifically, the more fearful and anxious the dog was found to be around strangers, the more likely the dog was going to have a reduced life span.
Unfortunately most pet dogs are not autopsied to find causes of death and dog owners are often a bit vague as to what actually caused their pet's demise. That means that a specific breakdown of the factors contributing to a particular dog's death might be difficult to obtain in a retrospective study like this which is based on dog owners' reports. However some disease conditions are easily visible to owners well before death. This study found that fearfulness (this is general fearfulness not stranger-directed fear) and separation anxiety both robustly predicted skin problems in dogs. This is particularly interesting because for humans there is a lot of data which shows that psychological stress is a good predictor of a number of skin diseases.
Dr. Dreschel summarizes her work by saying, "It was hypothesized that stress caused by living with anxiety or fearfulness has deleterious effects on health and lifespan in canines. The ﬁndings indicate that fear, speciﬁcally the fear of strangers, is related to shortened lifespan."
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
Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission
Data from: Nancy Dreschel (2010). The effects of fear and anxiety on health and lifespan in pet dogs. Applied Animal Behaviour Science 125, 157–162