In animals, brain size is often correlated with executive function and overall intelligence. Many studies have been done, on primates specifically, to compare how brain size affects an animal’s ability to complete different tasks or behaviors. Recently, one study looked at dog brain size by breed. The dogs with larger brains performed better on short-term memory tasks and self-control.
But, we shouldn’t be so quick to judge the dog breeds with the smallest brains. Their brains may be smaller, but their brain-to-body size ratio is higher. Some scientists believe that the brain-to-body size ratio also plays a role in intelligence. Let’s find out which dog breeds have the smallest brains.
Dog Breeds With the Smallest Brains
On average, brain size in dogs has a 1:125 ratio when compared to body size. There is some slight variation, but this is average proportions for all dogs. Therefore, the dogs with the smallest bodies are also the dog breeds with the smallest brains.
1. Chihuahua
Height: 5-8 inches
Weight: Under 6 pounds
Chihuahuas are the smallest dog species. Believe it or not, they actually have the largest brain when compared to the body size of any dog. This tiny breed originated in Mexico and rose to popularity in the 1990s and early 2000s. Chihuahuas are known for having a big attitude to make up for their small bodies.
2. Pomeranian
Height: 6-7 inches
Weight: 3-7 pounds
Pomeranians are not much larger than chihuahuas and they are also considered to be companion lap dogs. These dogs are prized for their long and fluffy fur that extends far beyond their bodies. The wild manes make these dogs look much larger than they actually are.
3. Yorkshire Terrier
Height: 7-8 inches
Weight: 7 pounds
Yorkies, as they are commonly called, are easily recognizable small dogs. They are a favorite companion dog thanks to their small size, glossy fur, and playful personality. Due to their small size, Yorkshire terriers are often bred with other small dogs to create unique mixes, like the yorkipoo.
4. Brussels Griffon
Height: 7-10 inches
Weight: 8-10 pounds
Brussels griffon dogs are not commonly seen. However, they are gaining popularity thanks to their permanent “grumpy” faces. A few older breeds, like pugs and cavalier King Charles spaniels, were bred to create the modern-day Brussels griffon. One of the distinguishing features of this short-nosed breed is its beard, which is often left untouched by owners during grooming.
5. Papillon
Height: 8-11 inches
Weight: 5-10 pounds
Papillons are frequently misidentified as pomeranians thanks to their long, fluffy coat. The name papillon comes from the French word for butterfly because their erect ears and coat create a butterfly shape around their faces. Fun fact: some papillon dogs have folded ears and even though they are the same breed, these dogs are referred to as phalene (meaning moth-eared).
6. Japanese Chin
Height: 8-11 inches
Weight: 7-11 pounds
Many believe that the Japanese chin is a breed descended from dogs in ancient China. This breed is known for its short nose and bulging eyes. Japanese chins have been popular lap dogs since they were introduced to the Western world.
7. 
Height: 11-13 inches
Weight: 8-12 pounds
Chinese crested dogs are a mostly hairless breed. Small tufts of hair can be found around their head, tail, and feet. Since the lack of hair is an incomplete dominant trait, some Chinese crested dogs are born with full coats (known as powderpuffs).
8. Miniature Pinscher
Height: 10-12.5 inches
Weight: 8-10 pounds
Miniature pinschers are small dogs that have a similar appearance to the larger doberman pinschers. These dogs are, in fact, not a miniature version of doberman pinschers. The confusion came due to their similar colorations and an incorrect translation by kennel clubs.
9. Maltese
Height: 7-9 inches
Weight: under 7 pounds
Maltese is another breed of a popular lap dog. This breed has a long history but there is debate about how the dog came to be named after the island of Malta. Historically, the dogs came in a variety of colors, but currently, white is the only coat color.
10. Toy Poodle
Height: Under 10 inches
Weight: 4-6 pounds
Now known for their attractive hair cuts and extensive cross-breeding, poodles were originally bred to water dogs that collected waterfowl for hunters. Members of traveling circuses were amongst the first people to begin selectively breeding poodles for a smaller size. Toy poodles are the smallest recognized size and full-size poodles can weigh up to 70 pounds.
11. Italian Greyhound
Height: 13-15 inches
Weight: 7-11 pounds
Italian greyhounds are the smallest breed of sighthounds, dogs that have a visual prey drive. These dogs were originally used for hunting small prey, but they are most commonly kept as companion dogs now. They are a distinct breed from the greyhound, but they are often confused due to their similar appearances.
12. Toy Fox Terrier
Height: 8.5-11.5 pounds
Weight: 3.5-7 pounds
The toy fox terrier breed originated from the smooth fox terrier. These dogs have small, athletic builds, but they are sometimes confused with chihuahuas and miniature pinschers. This active breed is known for its intelligence and trainability.
13. Miniature Dachshund
Height: 5-6 inches
Weight: Under 11 pounds
The long-bodied “wiener dog” was originally bred for its hunting ability. The long body shape allowed the dogs to easily fit into burrows and chase prey through the underbrush. Miniature dachshunds are known for being stubborn and mischievous, making them sometimes difficult to train.
Does a Small Brain Mean a Stupid Dog?
A small brain does not necessarily mean that small dogs are lacking intelligence. One study looked at dog brains by breed and found that the brains were more developed in different areas. The differences in brain structure correlated with the traits that the breeds had been selectively bred for. For example, German shepherds are commonly used in scent-detection work. The part of their brain that colors their olfactory (smell) response is well-developed.
So, each breed is smart in its own way, regardless of the size of its brain. We have bred dogs to be a diverse group with different talents thanks to selective breeding and breed standards.
