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8 Ways Your Dog’s Personality Can Change Over Time

There's no question your dog changes physically as she ages, but what about behavior and temperament? Most owners expect their dogs to act the same throughout their lives, but this study of over 1,600 dogs suggests otherwise. Be prepared for these eight possible personality changes.

canine personality


  • Researchers at the University of Helsinki have released the results of a large-scale study that confirms that breed “is the most important determinant underlying personality differences” between dogs
  • The study coauthors also assert that, “While the breed is the most important factor underlying personality, many genetic and non-genetic factors have a complex effect on personality”
  • A 2019 study suggests that like humans, dogs’ personalities change — often significantly — as they grow older
  • One of the most important findings of the study was that dogs’ responsiveness to training increases steadily from puppyhood, peaks at six to eight years, and then begins a gradual decline during which it’s still possible to “teach an old dog new tricks”
  • Another finding is that attendance at obedience classes is associated with more positive personality traits throughout a dog’s life

Like humans, dogs are individuals, and in the case of our canine companions, it has been generally assumed that breed plays a significant role in shaping personality. Recently, a study by researchers at the University of Helsinki published in the journal iScience has confirmed this assumption.

“The breed of the dog is the most important determinant underlying personality differences. All dogs are individuals, and all breeds have different traits, but the breeds differ in what kind of personality most dogs within each breed have,” says lead study author and postdoctoral researcher Milla Salonen.

Study Evaluated Over 11,000 Dogs and 300 Different Breeds

For their study, Salonen and colleagues from the canine gene research group at the university compiled survey data on over 11,000 dogs across 300 different breeds in 52 breed groups. The ages of the dogs ranged from under a year to 17 years, with a mean of 5 years. Over half the dogs were female (53%) and three-quarters (76%) were intact.

The purpose of the data collection was to investigate environmental and other factors related to personality. Prior to this study, breed differences had never been investigated using such a large population of dogs, and in fact, many of the breeds and breed groups included in the current study had never been looked at, at all.

According to coauthor Hannes Lohi, a professor from the Faculty of Veterinary Medicine:

“This study provides a topical update on the effect of the breed on the dog's personality, since in an American study published last year that effect was considered to be very minor. While the breed is the most important factor underlying personality, many genetic and non-genetic factors have a complex effect on personality.”

Puppy Socialization Is Most Important Environmental Factor

The study looked at the link between various factors and the following seven personality traits:

  1. Insecurity
  2. Training focus
  3. Aggressiveness/dominance
  4. Energy
  5. Dog sociability
  6. Human sociability
  7. Perseverance

Not surprisingly, of the environmental factors analyzed, socialization in puppyhood (between seven weeks and four months of age) carried the most weight. A wealth of socialization experiences in puppies was associated with lower insecurity and aggressiveness/dominance, higher training focus, and higher human and dog sociability.

“Our findings indicate that new owners should familiarize their puppies as much as possible with unfamiliar people, places and animals. Of course, socialization must always be done on the puppy's terms, which means that the puppy must not be forced into frightening situations,” says Salonen.

Age also showed a strong influence on behavior. In older dogs, the mean for the training focus trait was higher than in young dogs. However, the mean was higher in younger dogs for insecurity, energy, and human and dog sociability.

Canine Personality Is Strongly Influenced by Genetics

The underlying factors accounted for only a small part of the variation in personality traits between individual dogs. According to the researchers, this fact coupled with the substantial differences noted between breeds, indicates that personality is also strongly influenced by genetics (i.e., breed).

The study authors note that likely, the environment of early puppyhood, including the care provided by the mother dog, is also of great importance, but this could not be determined in the study.

“Based on our research, personality traits are extremely complex and have astounding similarities between dogs, humans and other animals,” Salonen says.

Personalities of Dogs Change Over Time

A 2019 study from Michigan State University showed that the personalities of family dogs change over time, and our interactions with them play a role in these gradual changes.

“When humans go through big changes in life, their personality traits can change. We found that this also happens with dogs — and to a surprisingly large degree,” William Chopik, professor of psychology and lead study author, explained in an MSU news release.

“We expected the dogs’ personalities to be fairly stable because they don’t have the wild lifestyle changes humans do, but they actually change a lot. We uncovered similarities to their owners, the optimal time for training and even a time in their lives that they can get more aggressive toward other animals.”

The study, published in the Journal of Research in Personality, is among the first and largest to evaluate changes in dogs’ personalities. The researchers developed an extensive survey of questions about dogs’ personalities and behavioral history.

The survey was answered by owners of over 1,600 dogs across 50 different breeds, ranging in age from a few weeks to 15 years, including a similar number of males and females.

The survey questions incorporated five aspects of the canine personality: fearfulness, aggression toward people, aggression toward animals, activity or excitability, and responsiveness to training. The owners also answered a survey about their own personalities.

Obedience Classes Reduce Fear and Anxiety

The researchers discovered, predictably, that younger dogs are more active and excitable than older dogs, and the decrease in activity level occurs gradually and steadily over the course of a dog’s lifetime.

The trait of aggression toward both people and other animals peaks in six to eight-year-old dogs, with both younger and older dogs showing lower levels of aggression of either type.

When it comes to responsiveness to training, the researchers found the trait increases steadily from puppyhood and peaks between the ages of six and eight, at which time it begins a gradual decline. However, the decline occurs no more rapidly than the rise from puppyhood to middle age, suggesting that it is indeed possible to “teach an old dog new tricks.”

One personality trait that rarely changes as a dog ages, according to the researchers, is fear and anxiety. However, they also report that dogs exposed to obedience classes tend to be less fearful overall.

“Exposure to obedience classes was associated with more positive personality traits across the dog’s lifespan,” said Chopik. “This gives us exciting opportunities to examine why personality changes in all sorts of animals.”

8 Ways Your Dog’s Behavior May Change With Age

Most pet parents realize their dogs will change physically as they get older, but many aren’t prepared for the behavior changes that can also accompany aging.

It goes without saying that any change in your pet’s normal behavior should be discussed with your veterinarian, because animals often express underlying physical problems through a behavior change. For example, a painful hip or back can result in one or more of the behaviors listed below.

  1. Anxiety — Dogs who are anxiety-prone as youngsters and adults (for example, those with noise phobias or separation anxiety) often become more so as they age.

    Positive reinforcement training may be helpful in curbing anxiety-related behavior in your dog, and it certainly can’t hurt as long as you don’t get too focused on results. It’s important to realize that just as you’ve dealt with some level of anxiety in your pet for years, you should expect and plan for amplification of those issues as she ages.

    Again, fun through playtime and exercise, along with social classes are great ways to help manage anxiety-based behaviors and build trust.
  2. Hypersensitivity, fears, and phobias — If your senior pet has deteriorating vision or hearing, even his own home can become a frightening place. Pets thrive on routine and consistency, and this goes double for aging companions who are having trouble navigating even familiar terrain.

    It’s important at this stage of your dog’s life to keep his environment consistent. Don’t arbitrarily move his food or water bowl, his crate, his bed, or his toys. Try to avoid rearranging the furniture in your home. Mealtimes and potty walks should be consistent from one day to the next, as well as exercise and play time.

    If your dog is becoming more sensitive to normal household or neighborhood sounds, play background music or keep the TV on to mask noises. Also rule out underlying pain as a root cause of new sound sensitivities.
  3. Aggression — Along with an age-related reduction in hearing, eyesight and sense of smell, your dog may startle more easily, and in some dogs, this can result in unprovoked aggression. The situation will require some sleuthing on your part, with the help of your veterinarian, to understand the specific causes or triggers of the behavior so a treatment or behavior modification protocol can be implemented.

    Enrolling in positive training classes (obedience, nose work, agility, etc.) through the 8-year mark when aggressive behavior potentially peaks is a great way to help keep a dog’s interactions with other humans and animals controlled, positive and relationship-oriented.

    Significant behavior changes may also require the help of a veterinary behaviorist, and I encourage you to contact one sooner rather than later if your older dog is having episodes of unprovoked aggressive behavior.
  4. Compulsive behavior — These are repetitive behaviors your dog may perform over and over, for no apparent reason. They can include constant licking (usually of a particular body part like a paw), which can result in hot spots. Other behaviors include repetitive tail chasing, spinning, jumping, pacing, “air biting,” and staring blankly into space.

    If a thorough workup by your veterinarian shows no medical cause for your dog’s obsessive behavior, she may be doing it to relieve feelings of anxiety or conflict. One way to try to break the cycle is to simply stop her as soon as she begins the behavior, by speaking calmly to her and petting or massaging her. Instituting a stress-reducing herbal protocol and increasing exercise and environmental enrichment as soon as you notice repeating behaviors is also wise.

    If the behavior is potentially dangerous or harmful and you don’t feel you can manage it on your own, talk with your integrative veterinarian or a veterinary behaviorist.
  5. Destructiveness — Sadly, some dogs become destructive as they age — a situation that can be quite disturbing for family members. You might lose a cherished belonging or two at this stage of your pet’s life, or he might turn his destructive urges on himself.

    Some older dogs develop pica (eating non-food objects) for the first time. Others seem driven to lick, suck or chew their own body parts, those of family members, or household objects. Digging and scratching can also become a problem. Many of these behaviors can be boredom-based, so maintaining daily environmental enrichment is crucial.

    Once again, it’s important to talk with your veterinarian about any destructive tendencies your dog develops to rule out an underlying physical cause. Meanwhile, you’ll want to dog-proof your home and belongings, and ensure your pet has plenty of appropriate raw bones and chews to gnaw on, but only when you’re around to supervise.
  6. Vocalizing — Excessive vocalizing is more common in older cats than dogs, but if your dog is growing more “talkative,” it can be unsettling because as her guardian, you want desperately to understand what she needs from you.

    An increase in vocalizing can be caused by the disorientation that comes with a decline in cognitive function. It can also mean your dog isn’t hearing things as well as she once did, or that she’s in pain.

    If your veterinarian has ruled out an underlying medical condition, try training your dog to respond to a gentle verbal cue such as “Quiet” or “Shhh”, and reward her lavishly for her efforts. However, keep in mind it’s possible she doesn’t realize she’s making noise, in which case she’s not likely to learn a verbal command to be quiet. If that’s the case, you’ll just need to distract her when she vocalizes by speaking quietly and reassuringly to her.

    I find lick mats and food-dispensing interactive toys are invaluable for distracting dogs that tend to vocalize excessively. You can’t bark when you’re working on a juicy raw marrow bone or licking frozen bone broth off a cookie sheet.
  7. Inappropriate elimination — If your older dog seems to have forgotten his housetraining, there are a number of potential causes, none of which involve deliberate disobedience. The first order of business is to make an appointment with your veterinarian to rule out any underlying disease process. Once that’s done, you’ll need to investigate other possible causes for inappropriate elimination, including decreased mobility, needing to go more often, or less control over his bladder or bowels.

    Initial steps you can take to resolve the problem include taking him outside more often to eliminate, and/or introducing/re-introducing him to a crate. It’s also important to recognize the difference between urine dribbling, over which your dog has no control no matter how often he goes outside, and urinating.
  8. Nighttime restlessness — Some older dogs develop a problem sleeping through the night. Age-related issues that can cause this change include loss of vision or hearing that affects sleep quality, the need to relieve herself more often, or an increased response to noises that never bothered her before.

    All dogs, including senior and geriatric pets, need age- and condition-appropriate exercise each day. If your dog gets some exercise already, try increasing the time she spends playing or taking walks. Add in several rounds of gentle tug-of-war with a rope toy throughout the day, or learn nose work, a great way to enrich your dog’s daily life.

    If she doesn’t get much exercise, start safely increasing her daily activity level. The goal is to tire her out physically, so she’ll be more likely to sleep at night. I’ve found hydrotherapy (swimming or walking on an underwater treadmill) to be the best way to assure older animals sleep through the night.

    If your dog needs midnight trips outside to relieve herself but is otherwise healthy (as confirmed by your vet), she may be taking in too much water before bed. Try removing her water bowl after dinner, and ensure she gets an opportunity to relieve herself right before you retire for the night.

    Let your dog sleep in your bedroom. Sleeping near her humans should help ease any anxiety that is contributing to her nighttime restlessness.

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