Why Are Dogs Different Sizes?

The vast difference in shapes and sizes in the canine world is bewildering. How can a particular species be so different physically? This question is expected since dogs are the most varied species on earth.

Why Are Dogs Different Sizes?

The main reason for the difference in dog sizes is selective breeding. Humans carefully select dogs and hybridize them so that they can perform various functions. As a result, they have succeeded in engineering more than four hundred dog breeds.

There are many different dog size options from which you can choose while adopting a puppy. But it would help if you considered your family members before you decide. For example, if you have many kids in your home, adopting a small-sized dog isn’t a great idea.

Why Do Dogs Come In Different Sizes?

The variations in dog shapes and sizes we see today occur due to the reasons below.


Humans domesticated dogs thousands of years ago because they wanted to utilize them as working partners. So, they began to breed them to be able to perform specific tasks. For instance, Labs can jump into the water to retrieve downed fowl thanks to their water-resistant coat, webbed toes and an otter-like tail.

Terriers can dig into burrows when hunting down rodents because of their small size. Humans bred sighthounds to be fast so they can chase down prey. Also, they bred sled dogs to have insulating coats, stamina, strong pack drive, and more.

With time, people stopped relying on dogs for work, which led to the birth of a new trend. People started breeding for appearance during the Victorian Era. Dogs became a symbol of status for the middle class, and more people kept dogs as pets at that time.

Many breed clubs were formed in the 19th century with the creation of many different breeds. It was expected given the expansion in how often people showed and enrolled dogs in sports.


Dogs come in many different sizes and shapes due to selective breeding. Studies have shown that breeding animals that are carefully selected for certain desired traits result in producing offspring with those traits.

In his book titled “On the Origins of Species,” Charles Darwin wrote that you could pass desirable traits down to future generations by breeding carefully selected animals with those traits. However, natural selection is prolonged, with changes occurring after thousands of years.

However, the process speeds up greatly with artificial selection, and changes occur in a few generations. According to researchers, selective breeding of wild plants and animals started over ten thousand years ago.


The many different sizes of dogs we see today are also a result of nature. Unlike other mammals on the planet, dogs possess a vast array of behavioural and physical variations. You can quickly notice these physical variations when you cross two breeds.

Although you may expect to get an average of the two types of breeds you crossed, a professor emeritus of biology, Raymond Coppinger, said that hybridization produces “phylogenetically bizarre.” That means something that had never been seen in evolutionary terms.

Producing dogs with a specific trait that people love is possible because of genetic malleability. It’s also why we have the variations in size that we see today.

What Are The Different Sizes Of Dogs?

What Are The Different Sizes Of Dogs?

Small Dog Breeds

Some examples of small-sized dogs include Chihuahua, Toy Poodle, Pomeranian, Labrador Retriever, Yorkshire Terrier, Shih Tzu, Pug, etc.

These are the type of dogs people carry around like babies. They weigh less and are easy to manage. Small-sized dogs make excellent family pets, and you can take cute pictures with them. They usually weigh less than two pounds when old enough to move to their forever homes.

Their tiny stature makes it easy for kids to pick them up. So, if there are many children in your home, you should not get a small dog.

What to Like:
• You can groom and clean them more quickly
• Perfect for small apartments
• Great travel buddies
• Ideal companion for seniors
• Cheaper overall feed

What We Don’t Like:
• Less sporty than medium-sized dogs
• Small dog breeds tend to bark more
• Training takes more time

Medium Dog Breeds

Some mid-sized dogs include French Bulldog, Bichon Frise, Cocker Spaniel, Jack Russell Terrier, Dachshund, Boston Terrier, etc.

Mid-sized dogs are excellent family companions. Although they cost more to manage than small dogs, you’ll find them less expensive than larger dogs.
These dogs are bred to perform specific functions such as hunting, herding, or performing different activities on the farm.

What to Like:
• Less fragile
• They mostly enjoy living a long life
• Typically cheaper Vet’s visit as compared to larger dogs

What We don’t like:
• Need more exercise
• Expensive toys due to their bigger size

Large Dog Breeds

Examples of large-sized dogs include Smaller Bulldog, Golden Retriever, Pitbull Terrier, Hovawart, Bernese Mountain Dog, etc.

What to Like:
• Can play rougher games
• Good for cuddling
• Excellent in guarding

What We don’t Like:
• Their poop is massive
• They scare others

What Size Dog Do I Own?

What Size Dog Do I Own?

We already know that there are many different dog size options from which you can choose. But how can you determine the type to which your furry pal belongs? Here’s a general guide to help you through it!

• Small dogs weigh from 2 to 22 pounds
• Miniature dogs weigh from 3 to 12 pounds
• Toy dogs weigh from 5 to 12 pounds
• Teacup dogs weigh from 4 or fewer pounds
• Medium dogs weigh from 24 to 57 pounds
• Large dogs weigh from 59 to 99 pounds
• Extra Large dogs weigh from 100 or more pounds


Of all the animal species on earth, dogs have the broadest range in size difference. It might not be easy to believe that a Chihuahua and a Great Dane are the same species when they stand beside one another. This variation in size is a result of selective breeding.

Humans breed dogs by carefully selecting two breeds and crossing them so that they can perform specific functions. These days, people do it to produce dogs with certain desirable traits and looks.

Small-sized dogs are adorable and inexpensive to keep. But they are not ideal for families with lots of kids.