6 Biggest Differences Between Small and Large Dogs (It’s Not Just Their Size)

The main difference between small and big dogs is obvious: one has small-man syndrome and can easily fit inside an oversized purse. The other are gluttons for pets and tend to barrel through life (and your home) like a bull in a china shop. OK, OK, stereotypes aside, the real physical distinction between the two is clearly size.

But when you’re debating between a pint-sized pup and a horse-sized dog, you shouldn’t weigh your entire decision based on the amount of physical space that your pup would take up.

The size of your prospective pup is just the tip of the iceberg — physical size can be an indicator of how much you’ll spend over time, your pup’s lifestyle, or even, yes, their personality.

“When deciding whether a big dog or a small dog is the better fit, lifestyle factors are critical,” says Dr. Antje Joslin, veterinarian consultant at Dogtopia. “Potential owners should consider their activity level, physical strength, living space, financial ability to manage medical care, long-term commitment, and how much time they can devote to training, exercise, and companionship.”

All that being said, every single dog is unique. While you can use breed and how large or tiny they are to make generalizations, anyone could do the same thing to any animal species (including humans) and quickly realize how that judgment is not one-size-fits-all. Just remember to evaluate your potential new family member on their individual qualities, too. 

Biggest differences between small dogs and large dogs

Physical size

This difference is the most obvious, but it is something to consider when your 90-lb. pooch climbs onto your lap for a nap because they don’t know how big they are. Large dogs are usually defined as weighing more than 55 lbs., though they can top out at more than 110 lbs., depending on the breed. Meanwhile, small dogs usually weigh less than 30 lbs. 

As a pet parent, it’s an important factor to consider. For example, if your pup is injured or incapacitated, is there someone in your household who can lift them and get them to the car? Large dogs also often don’t know their own strength, so a 110-lb. dog pulling on a leash has the potential to yank you down the street or get loose on their leash than a 25-lb. dog, which is something else to consider.

Space requirements

Having a high-energy German Shepherd trotting around a studio apartment isn’t ideal for that pup — or their humans. Some large dogs do require bigger spaces like a house with a yard versus small dogs who would be happy playing in a one-bedroom apartment as long as there’s enough room to play fetch.

“Space requirements are influenced more by energy level than size alone, but large dogs typically need more room to move comfortably and rest without physical strain,” Dr. Joslin says.

Large dogs don’t always need big spaces, though. A Great Dane or Greyhound might not mind living in a small apartment because they prioritize rest and are known for being indoor couch potatoes. 

Lifespan

Unfortunately, the lifespans for small breeds and large breeds do differ. “Large breeds tend to have significantly shorter lifespans,” Dr. Joslin says. The average life span for a large dog can be nine to 12 years, while a small dog can live up to 15 years. Large breeds “are more prone to orthopedic conditions such as hip and elbow dysplasia, cruciate ligament injuries, and arthritis, and an increased risk of bloat,” she adds. “Small breeds generally live longer but are more prone to dental disease, tracheal collapse, cardiac disease, and certain metabolic or congenital issues.”

That said, illnesses, injuries, and cancer can unexpectedly cut any dog’s lifespan cruelly short. As much as we wish these estimates could be definitive facts, each dog is an individual with a unique set of circumstances. And on the other side of the coin, a large dog might outlive their life expectancy range. 

Food requirements 

This is a sneaky difference — but a notable one. Large dogs simply eat more than small dogs, and their foods are also formulated differently. There’s a reason there is a small-breed and large-breed food option at the stores.

Small dogs have higher metabolisms, smaller throats, and smaller stomachs, so their food tends to be smaller pieces of kibble and be more calorie-dense to support their bodies. Meanwhile, food for large dogs tends to contain bigger pieces of kibble but it is less caloric and contains less fat to support bone health and prevent issues like obesity, which cause stress on the joints. 

Costs

Large pups are going to take more money out of your wallet in the long run. On the everyday end, they’re going to go through more bags of food. When it comes to travel, a small dog, which can fit in a dog carrier, can fly in the cabin on most planes with a fee around $150 to $200. Large dogs, however, will likely have to fly in the cargo hold and fees vary widely from $200 to $1,000, though there are some dog-friendly airlines that’ll allow you to buy a seat for your pup.

“From a veterinary standpoint, long-term medical costs may differ, with large dogs often incurring higher expenses related to disease and medications simply due to their size,” Dr. Joslin says.

Exercise needs 

Large-dog parents may be spending more time outside with their pup on walks and playing. “Large dogs generally require more structured physical exercise to maintain muscle tone, joint health, and mental well-being,” Dr. Joslin says. “Small dogs often can meet a significant portion of their exercise needs through normal daily activity and indoor movement.”

That doesn’t mean small-dog parents can phone it in, though, she says, adding that “many small breeds still require regular walks and mental stimulation, and some high-energy small breeds can be just as demanding as larger working dogs.” So potential small-dog parents shouldn’t assume that their dog’s exercise needs will be low-maintenance. 

Behavior

While it’s easy to assume that small and large dogs are trained equally, that often isn’t the case, and this discrepancy can cause differences in behavior.

“While training often seems to focus more on large-breed dogs because their size and strength can make even minor behavior problems unsafe, small dogs are often unintentionally allowed to develop undesirable behaviors because they are easier to manage physically,” Dr. Joslin says. So if you get a small dog, do everyone around you a favor by making sure that they’re well-trained.  

That brings us back to that old chestnut “small-man syndrome,” the idea that small pups are more vocal and aggressive. Although it definitely applies in some cases, it isn’t universally true because every dog is different.

“Though it may be tempting to link behavior and temperament to a dog's size, many factors come into play, including breed, age, training, and an individual dog's personality,” Dr. Joslin says. “It is therefore difficult to make large generalizations based on size alone. Dogs and humans are affected by many factors, such as their early life experiences, training (or lack of training) at home, and their interactions with other dogs and pets.”

How should you decide what size of dog to get 

It’s your personal preference and also whether or not your lifestyle meshes well with the breed size. “Large dogs often require more physical effort, space, and planning, while small dogs may be more portable and adaptable to variable living circumstances,” Dr. Joslin says. “Ultimately, the best choice is less about size alone and more about matching the dog’s needs to the owner’s daily life, expectations, and ability to provide lifelong care.”