Big dogs, Small dogs: Does size affect behavior? · The Wildest

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Big dogs, Small dogs: Does Size Affect Behavior?

How is the experience of having a large dog different than that of having a small dog?

Big and small dog standing together at a park
Andreas Schmolmueller / Pexels

When it comes to dogs, size really does matter. While some prefer pocket-sized pups for their portability, others like their dogs to be more on the XL side. Size-based biases are also common. And anyone with big dogs knows that people sometimes fear them even when their behavior is exemplary and a small dog is present whose behavior is not.

One of the marvels of domestic dogs is the astounding range of sizes they come in, which is determined by a very small number of genes. (In comparison, roughly 200 gene regions affect height in humans.) Since so few genes influence size, how does it affect behavior?

Are big dogs just compensating for something with their rowdy behavior? Do all small dogs have a superiority complex? Or are people’s behavior and expectations different based on the dog’s size? Here’s everything you need to know about dogs, big and small.

Life with Big Dogs vs. Small Dogs

A dog’s size has practical consequences. Here are a few examples:


Ask anyone with a Great Dane suffering from diarrhea, an experience that’s not quite the same for someone with a similarly afflicted Maltese. 


Dealing with a seven-pound Affenpinscher who prefers not to get into the car may require nothing more than a matter-of-factly picking them up and putting them inside. The situation is far more challenging when a 185-pound Saint Bernard is involved. Helping a large dog with mobility issues can be physically demanding for the caregiver.


Big dogs can be more expensive in every way, from the cost of food, professional grooming, and medication to toys, leashes, collars, and food bowls.


People with little dogs who don’t want them to help themselves to food simply avoid picnicking on the floor and are careful not to leave chairs where they can be used as stepping stones to the table or counter. People with large dogs often find that no place lower than the top of the refrigerator is safe or truly off-limits. 


With a large dog, the accidental consumption of dangerous foods, such as chocolate, is far less likely to lead to serious consequences than for a smaller dog because it takes much more for the dose to be toxic to a larger dog.


Giving your pup a few treats? Those extra treats that lead to weight gain in smaller dogs may be no big deal for a large dog. 


Some worry about big dogs around children, but I must confess that I worry when we dog-sit a friend’s six-pound Pomeranian. Even gentle and respectful kids can collide with small dogs and cause an injury completely by accident. With bigger dogs, that isn’t as much of a concern.


It’s easier to rent an apartment with a small dog (weight limits favor them); tight living spaces may be easier to share, and getting small dogs into and out of an apartment building, especially while you’re housetraining them, is far less of a challenge. 

Are behavior differences determined by size?

For the most part, the answer is a resounding “No.” Behavioral differences in dogs are not size-based. Dogs of all sizes love to play chase, fetch, go on walks, run off-leash, meet new people, romp with their best dog buddies, participate in training sessions and eat tasty treats. By the same token, dogs of all sizes are vulnerable to sound sensitivity, exhibit separation anxiety and aggression, jump on people inappropriately, bark excessively, chew on shoes, dig in the garden, or have accidents on the floor. They all wag their tails (if they have them) in joy.

And yet, there are clearly differences between individual dogs beyond age, gender, and the environment in which the dog lives and was raised. So, what gives? Turns out it’s a people problem.

People Treat Small Dogs Differently

One  study examined the connection between size and behavior in great detail, addressing these questions: How does a pet parent’s behavior toward dogs of unequal sizes influence their dogs’ behavior? How do expectations of dogs based on their size differ?

The study found that there are significant differences in behavior between large and small dogs and between pet parents of large and small dogs. Small dogs were reported to be less obedient, slightly more often aggressive or excitable, and more anxious and fearful. People with small dogs also reported a lower level of consistency in their interactions and enforcement of rules than did those with larger pups. Differences in people’s behavior may account for the higher rates of disobedience in small dogs.

It’s All About That Baby Talk

Have you ever noticed how some people treat their small dogs like they’re babies? Babyish features affect human caretaking behavior; we’re evolutionarily hardwired to find big eyes, small size, and proportionally large heads endearing. Psychologists call this the “Aww phenomenon.” If babies weren’t so cute, parents could be less likely to respond to their needs, and the offspring would be less likely to survive.

Dogs seem to elicit this same “aww” response in humans, especially small dogs, and even more so, breeds with pronounced juvenile features such as Cavalier King Charles Spaniels, Chihuahuas, Japanese Chins, Pugs, and Boston Terriers. Since babies affect our hormones, raising the levels of oxytocin — nicknamed “the love hormone” — it stands to reason that adorable dogs do, too.

Socialization Plays a Role Too

Typically, large dogs have more opportunities for socialization than small ones. When small dogs are carried around rather than moving around on their own four paws, they have fewer interactions with people and other dogs, which can limit their ability to cope with them. 

Positive experiences with other people and dogs during puppyhood are the best way for a dog to develop good manners. But small dogs are often picked up or otherwise physically manipulated, which may result in more negative experiences. Absent enough of those positive experiences and dogs of all sizes will face social challenges.

Two research studies found that small dogs receive less formal training than large dogs. Also, people play fetch more often and do more tugging and nose work with big dogs than with small ones and are more likely to take them running or biking.

Encouraging Misbehaviors

Though many pet parents have the same rules for dogs of any size, what large and small dogs are allowed to get away with is often different. Small dogs are  more likely to be allowed in our beds and on our laps. Having a 25-pound dog jump or sit on you is one thing, but having a 100-pound dog do it is another. Behaviors considered a nuisance in a small dog may be deemed antisocial in a large dog. Even aggression and other serious behavioral issues are more likely to be tolerated in small dogs. 

For example, some pet parents encourage little dogs to jump up on people and get on the furniture but rarely invite big dogs to do so. Large dogs are  more likely  to be euthanized for aggression, though another  study found that the average “biter” tended to be a smaller dog. Part of that is about the perceived threat. While dogs of both sizes can be equally aggressive, the size factor may affect fear response.

And Then There’s Breeding

In some ways, there are correlations between size and breed characteristics. Many small dogs are terriers and earth dogs, types that have been deliberately developed to be tenacious and curious as well as to dig and explore. If dogs are bred for those characteristics, such behavior will have far more to do with genetic influences on behavior than with size.

One  study found that small dogs were more likely than large dogs to come from pet stores, which generally acquire their “stock” from puppy mills. When you consider that puppy mills are notorious for environmental deprivation and risky breeding practices, it is perhaps no surprise that small dogs are burdened with more problematic behavior.

The behavior of dogs is what makes them such great companions and friends. So, when it comes to pets, size really doesn’t matter. What does matter are the experiences you have together — the good, the bad, and the shoe-chewing ugly. It’s always big love, no matter what size the dog.


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Karen London holding up a small dog

Karen B. London, PhD, CAAB, CPDT-KA

Karen B. London, Ph.D., is a Certified Applied Animal Behaviorist and Certified Professional Dog Trainer who specializes in working with dogs with serious behavioral issues, including aggression, and has also trained other animals including cats, birds, snakes, and insects. She writes the animal column for the Arizona Daily Sun and is an Adjunct Professor in the Department of Biological Sciences at Northern Arizona University. She is the author of six books about training and behavior, including her most recent,  Treat Everyone Like a Dog: How a Dog Trainer’s World View Can Improve Your Life.

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