10 Interesting Facts About Your Dog's Brain

1. How Big is a Dog’s Brain?

Compared to humans, a dog’s brain is smaller, about the size of a lemon or tangerine. However, MRI studies have shown that even though dog brain size is smaller, all the basic structures that are found in humans are present. These include the cerebral cortex, cerebellum, brainstem, hippocampus, amygdala, and basal ganglia. Like humans, dogs have a hippocampus which makes it possible to remember things. Their amygdala also makes it possible for them to experience a variety of emotions.

The similarity of the structures of dog and human brains suggests that there may also be a certain commonality in function.

2. Dog Brain vs. Human Brain

Here are the main differences between the brains of dogs and humans:

• The brains of dogs are smaller than humans in relation to overall body size. In humans, the brain-to-body ratio is 1:40 while in dogs it’s 1:125.
• The brains of humans have more folds, which means more surface area. The cortex of dogs is smaller and has fewer folds. This means there is less surface area and fewer neurons. Without as many folds as the human brain, dogs have a lesser capacity for higher thinking.
• The part of the brain where higher-level processing and thoughts take place (called the prefrontal cortex) is more developed in humans.
• The frontal lobe of a dog’s brain occupies only 10% of the brain while in humans it’s the front third of the brain.

3. Encephalization Quotient (EQ)

The encephalization quotient (EQ) accounts for the relationship between brain and body size, such that an EQ=1 means an animal has an average brain size for its body weight. The EQ of humans is about 7.4, while dogs have an EQ of 1.2 which is a bit better than the average mammal.

4. Keen Sense of Smell

A larger portion of dogs’ brains is dedicated to analyzing smells. The olfactory system of dogs is responsible for their sense of smell. It comprises about 2% of the total weight of the brain, while it’s only 0.03% in humans. Their olfactory bulb, which is a part of the brain that’s concerned with the sense of smell, is also bigger compared to humans.

Experts think that dogs can associate a scent with memories, which makes them valuable in sniffing contraband, explosives, drugs, and as members of search and rescue teams.

The scent-detecting cells and nerves in the nose of dogs and humans convey information to the brain. The real estate by which these scent-detecting cells are located depends to a large extent on the size and length of the nose, which in turn depends on the shape of the skull.

The shape of a dog’s skull is generally classified into:

• Dolichocephalic - dogs with elongated skulls and long noses (e.g. Greyhounds, Dachshunds, Great Danes, Collies)
• Brachycephalic - dogs with short noses and flat faces with broad skulls (e.g. Pugs, Boxers, Pekingese, Boston Terriers). With their short noses, these dogs have less space for scent-detecting cells compared to dolichocephalic dogs.
• Mesocephalic - dogs whose skulls are of intermediate length and width (e.g. Golden Retrievers, German Shepherds, Pomeranians, Beagles)

5. Intelligence Differs Between Dog Breeds

In 1994, Stanley Coren, a Professor of Canine Psychology at the University of Columbia wrote the book “The Intelligence of Dogs”. In it, he defines three aspects of canine intelligence -- instinctive intelligence, adaptive intelligence, and working and obedience intelligence.

Coren’s book also ranked 130 breeds of dogs based on intelligence. The top 5 brightest breeds are:

1. Border Collie
2. Poodle
3. German Shepherd
4. Golden Retriever
5. Doberman Pinscher

Another category ranked working dog breeds based on their ability to understand new commands and obey the first command. The top 5 excellent working dogs include:

1. Pembroke Welsh Corgi
2. Miniature Schnauzer
3. English Springer Spaniel
4. Belgian Shepherd Dog (Tervuren)
5. Schipperke and Belgian Sheepdog

6. Dogs Can Develop Age-Related Cognitive Dysfunction

Considering that dogs’ brains have similar structures and functions to the human brain, dogs also have a risk of developing age-related cognitive dysfunction, similar to Alzheimer’s disease, as they get older. This also means dogs may develop other medical conditions such as brain cancer. The pathogenesis of brain tumors in dogs has been observed to have a similarity with humans.

7. Dogs Have Feelings

In MRI studies conducted by Dr. Gregory S. Berns, the brains of dogs showed similar reactions to humans when exposed to stimuli, such as pain, a baby crying, traumatic events, etc. In the same study, most of the dog subjects have brain systems that are highly attuned to positive reinforcement. Dogs were also able to process human faces.

Dogs are capable of feeling happiness, sadness, fear, depression, anxiety, and even jealousy. However, they are incapable of experiencing more complex feelings.

8. Dogs Can Suffer from Depression

According to Dr. Jill Sackman, a veterinarian and owner of Animal Behavior Consultants, serotonin is an important neurotransmitter in the brain of dogs and humans. Serotonin regulates happiness, anxiety, and other feelings. Depression and anxiety in dogs and humans have been linked to low serotonin levels.

Dogs can experience depression and anxiety like humans. Giving them anti-anxiety medications used by humans, like Prozac, can help improve symptoms associated with depression and anxiety.

9. Dogs Can Recognize Human Faces

The bilateral temporal cortex of dogs’ brains helps them recognize faces. A study was able to observe that dogs are excellent at distinguishing between two humans and can pick up small but important signals in a human’s face.

10. Dogs Dream

Like humans, the brains of dogs function similarly and show a difference in the brain wave patterns associated with the two basic stages of the sleep cycle --- slow-wave sleep and rapid-eye movements (REM) sleep.

Since the brains of dogs and humans go through similar stages of electrical activity during sleep, this led experts to conclude that dogs dream, too. There have also been studies that were able to demonstrate similar brain wave patterns in humans and dogs.

Read more:

10 Facts About Your Dog’s Eyes

10 Facts About Your Dog's Ears

5 Myths About Your Dog’s Digestive Tract

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