My favorite wooden salad servers are decorated with Bugsy’s teeth marks. Excluding unprovoked attacks on innocent squeaky toys and the occasional disemboweling of one of his stuffed animals, he wasn’t a destructive chewer by nature, and never damaged anything else. When I came home from work and saw him enjoying these Costa Rican souvenirs, I could hardly blame him, and felt no irritation whatsoever. I understood: it was hunting season.
Because we had a strong aversion to being mistaken for deer and accidentally shot, our exercise was severely limited during the 10 days that hunters roamed the area. Instead of two daily off-leash romps in the woods around our 150- acre farm, we took leash walks down the road. It was clearly not enough for Bugsy, who compensated by chewing on the wooden “sticks” that were conveniently lying around. Every time I use the salad set, I’m reminded that even with well-trained dogs, exercise matters if you want good behavior.
Training obviously helps with problem behaviors, but it’s not the only way to avoid trouble. Dog trainers have long valued the role of exercise in minimizing irksome canine activities such as barking, chewing, jumping around like lunatics, being unable to settle down or sleep well, digging, whining and relentless attention-seeking.
One casual experiment supports these views: a group of dogs was divided in half; one half worked on formal training while the other half had their exercise increased to two 30-to-45-minute sessions a day. After six weeks, the dogs who had additional training showed improvements in both their responsiveness to cues and their problem behaviors. The dogs who had extra exercise also exhibited problem behaviors less frequently, although their responsiveness to cues had not improved.
The relationship between exercise and behavior is complex and sometimes surprising. For example, Schneider et al. (2013) reported that more exercise was correlated with lower levels of fear, less aggression towards familiar dogs and reduced excitability. Jagoe and Serpell (1996) found that dogs acquired for the purpose of increasing their owners’ level of exercise have a lower incidence of certain types of aggression, including possessive aggression and socalled dominance aggression. Lindsay (2005) hypothesized that this is due to the general physiological effects of exercise. So, how does exercise affect behavior through physiological means?
Endogenous chemicals (those produced by the body) may play a role in the effects of exercise on physiology and behavior. Like people, dogs can achieve an emotional state described as the “runner’s high,” which may be why the chance to go for a run is greeted with enthusiasm by our canine companions. It may also be why so many people believe the old saying, “A tired dog is a good dog,” though the admirable behavior exhibited by dogs who are well-exercised may be due more to chemistry than to fatigue.
A runner’s high is caused by chemicals called endocannabinoids, which signal the reward centers of our brains. Endocannabinoids lessen both pain and anxiety as well as create feelings of well-being. Running triggers higher levels of these compounds, which is why running makes us feel good.
If you just snorted derisively and thought that running makes you feel terrible and you can’t imagine why people put themselves through such misery on purpose, you aren’t alone. Though most dogs are excited about running, the human species, outside of a small percentage of fanatics of the sport (or weirdoes, as we are sometimes called), isn’t interested. Yet, the potential to activate the chemicals that cause a runner’s high exists within all of us. The capacity to experience that rush of good feelings is shared by dogs and people, even if we aren’t all dipping into it as frequently as our long-ago ancestors, for whom running long distances was part of daily life.
A study by Raichlen et al. (2012), “Wired to run: exercise-induced endocannabinoid signaling in humans and cursorial mammals with implications for the ‘runner’s high,’” investigated the phenomenon. The researchers predicted that running would result in chemical reactions in the brain associated with pleasure in species with a history of endurance running, but not in species whose natural history does not include running. They studied three types of mammals—humans, dogs and ferrets—and found that the two with distance running in their evolutionary pasts (humans and dogs) exhibit elevated levels of one particular endocannabinoid (anandamide) after running on a treadmill. Ferrets, noncursorial animals, had no such chemical response.
Both canine and human brains are made to enjoy running, but this pleasurable, rewarding quirk of chemistry is not universal among mammals. Ferrets, as the study showed, derive no pleasure from it. (Friends who despise running have expressed alarm at the results of this study—it makes them wonder if they are part ferret.)
The behavioral benefits to dogs of running may be related more to contentment than to fatigue. Perhaps, what we call “tired” is actually better described as “happy,” “relieved of anxiety and pain” and “experiencing feelings of well-being.” If so, exercise may indirectly benefit dogs’ behavior because it elevates mood rather than simply makes them too worn out to misbehave. Since endocannabinoids lessen the anxiety that can be a source of problem behaviors, it’s easy to see how exercise could help.
Running is also associated with the production of other chemicals that reduce anxiety in mammalian brains. Schoenfeld et al. (2013) reported that mice given the opportunity to run handled stress and anxiety better than sedentary mice. The study observed the brains and brain activity in both groups of mice and found that runners had more excitable neurons in the ventral hippocampus, which plays a role in anxiety, than did sedentary mice. However, the active mice also had more cells capable of producing the calming chemicals that inhibit activity in that area of the brain, which lessens anxiety. The study supports the idea that for mice, at least, running improves regulation of anxiety through inhibitory activity in the brain. It is possible that the situation is similar in dogs, though without studying them specifically, we can’t know for sure.
Of course, behavior and physiology, and the links between the two, are never completely straightforward. There is evidence that cannabinoids can cause hyperactivity at low doses, even though they have calming effects at higher doses. What does this mean for our dogs?
Age, breed and individual differences play a role in the amount of exercise required to keep dogs’ halos on straight and prevent them from sprouting little horns, behaviorally speaking. Some thrive on small amounts of exercise. For others, the same amount of exercise— perhaps a leash walk at a leisurely pace—has the opposite effect. It invigorates them, and may actually induce hyperactivity. (That’s a bit discouraging for those of us whose goal is rarely, if ever, to pep dogs up, though some who compete in canine sports try to do exactly that.)
Recently, I was concerned that I might be inadvertently energizing a dog my family was watching. Super Bee, a Border Collie, belongs to professional runner and Adidas Ultra Team member Emily Harrison. Emily often trains with her dog, so Super Bee typically runs 60 to 70 miles a week. To say she is extremely fit is an understatement along the lines of me saying I sort of like dogs.
While Super Bee was with us, we made exercise a top priority. She went along on all of my morning runs, and my husband ran with her in the evenings. We supplemented this activity with long sessions of fetch; luckily, neither our kids nor Super Bee became bored with this game. Still, knowing that despite our best efforts, we would be unable to give Super Bee her usual amount of exercise, I worried that the shorter sessions would just amp her up.
Despite that risk, I never considered not exercising her, and I’m certainly not advising skipping out on getting a little bit of exercise if that’s all you can do. Exercise and the outings involved in getting it have benefits well beyond those provided by elevated endocannabinoids. There’s value in understanding the effects of various amounts of exercise on our dogs; various types of exercise, from hiking to swimming to playing tug, may have different effects as well.
Though we did not exercise her as much as Emily does, we made a good effort. Super Bee even seemed tired (or should I say contented?) a couple of times! It didn’t last long, but we’re still proud of our accomplishment. It probably contributed to Super Bee’s model behavior while she was with us.
Besides the well-known physical benefits of exercise, its psychological and behavioral benefits are profound and contribute to a high quality of life. The reduction of annoying behaviors and the good behavior that arises directly or indirectly from exercise certainly make the beautiful relationship between people and dogs that much better. What more could we want for our dogs than the highest quality of life, minimal anxiety, the most elevated feelings of contentedness and the best possible relationship with us?