Do Dogs Dream?

1. Dogs Perceive the World Primarily Through Smell and Sound

In other words, the average human being has a nose that contains only 2 percent of the number of odor-analyzing cells that can be found in the nose of the little Beagle.

Smell dominates canine perception. While humans rely heavily on sight, a dog's brain is forty times more dedicated to analyzing smells. Dogs actively work to gather scents, wiggling nostrils independently and using a special sniffing mechanism to trap odor molecules. Their olfactory surface area is vastly larger than a human's, allowing them to detect scents at concentrations thousands of times lower than we can, especially animal-related odors like those in sweat.

Hearing is also highly sensitive. Compared to humans, dogs have similar hearing sensitivity in the middle range (human speech), but are significantly more sensitive to higher frequencies. They can hear sounds up to 47,000-65,000 Hz, far beyond the human limit of 20,000 Hz. This superior high-frequency hearing evolved to detect the sounds of small prey like mice and rats.

Vision is less detailed. Dogs do see color, but their vision is limited to shades of yellow, blue, and gray, unlike the full spectrum humans perceive. Their visual acuity is also much poorer; what a human can see clearly at 75 feet, a dog can barely recognize at 20 feet. However, dogs are much better at detecting motion and seeing in dim light due to larger pupils, more rods, and a reflective layer (tapetum) in their eyes, which also causes their eyes to glow.

2. Dogs Experience Basic Emotions, But Not Complex Social Ones

This means that a dog will have all of the basic emotions: joy, fear, anger, disgust, and even love.

Dogs share core emotions. Like humans, dogs possess the same brain structures, hormones (including oxytocin linked to affection), and chemical changes associated with emotional states. While historically debated, science now accepts that dogs experience a range of emotions.

Emotional range is limited. Research suggests a dog's emotional capacity is roughly equivalent to a human child aged two to two and a half years. This means they feel primary emotions like joy, fear, anger, disgust, and love.

Complex emotions are absent. Dogs do not experience secondary, more complex social emotions that require self-awareness and learned social constructs, such as:

• Guilt
• Pride
• Shame
• Contempt

What appears to be guilt (e.g., after an accident indoors) is actually fear of anticipated punishment based on past experience.

3. Genetics and Early Experience Shape a Dog's Personality

In dogs, a large proportion of personality is due to inherited genes.

Personality is largely genetic. Just as humans inherit predispositions, a significant portion of a dog's personality traits are determined by genetics. Selective breeding has amplified certain traits in different breeds, such as the easygoing nature of Newfoundlands or the intense focus of Border Collies.

Environment plays a crucial role. While genetics provide a foundation, early socialization is perhaps the most critical factor in shaping a dog's confidence and temperament. Exposure to a variety of people, places, and situations during key developmental windows (especially before 14 weeks and between 5-8 months) helps prevent fearfulness and anxiety.

Fear and anxiety can develop. Dogs can develop phobias from traumatic events or lack of socialization. Signs include flattened ears, cowering, trembling, and sometimes aggression. Comforting a fearful dog can inadvertently reinforce the fear, while ignoring the anxiety and acting normally, or using behavioral modification and sometimes medication, can help manage it.

4. Canine Communication Involves Barks, Tail Wags, and Scent Marks

Perhaps the most common misinterpretation of dog behavior is based on the myth that a dog who is wagging his tail is happy and friendly.

Barking is an alarm system. Domestic dogs bark far more than wild canines, a trait likely selected by humans for guarding. Barking is primarily an alert signal, not necessarily aggression unless low-pitched and mixed with growls. Different bark patterns convey specific messages:

• Rapid bursts: "Alert the pack, something's happening!"
• Continuous, low-pitched: "Danger is close, get ready!"
• Short, sharp barks: "Hello!"
• Long, solitary barks: "I'm lonely."
  Responding to a dog's alert bark by checking the situation and calmly reassuring the dog is the appropriate response, acknowledging their role as a sentinel.

Tail wags are complex signals. Tail wagging is a social signal used only when other living beings are present. Its meaning depends on position and movement:

• High tail: Dominance, confidence, potential threat
• Mid-level tail: Relaxed
• Low tail: Submission, fear, insecurity
• Tucked tail: Extreme fear
• Fast wag speed: High excitement level
• Broad wag sweeps: Positive emotion (happiness, friendliness)
• Small, rapid movements: Anticipation, readiness to act

Urine is a scent-based newspaper. Dogs use urine, rich in pheromones, to communicate information about their age, sex, health, and emotional state. They prefer marking vertical surfaces to elevate the scent and make it last longer. The height of the mark can even signal the dog's perceived size. Sniffing urine marks is how dogs "read" the latest news about other dogs in the area.

5. Dogs Possess Basic Quantitative Abilities, Including Simple Math

These observations suggest that dogs not only can count, but also can do simple addition and subtraction.

Dogs can judge size and number. Research shows dogs can easily distinguish between objects of different sizes and can judge which of two groups contains more items without counting. This ability, called numerosity, is demonstrated by their preference for larger piles of food.

Simple counting is possible. Working and sporting dogs, like retrievers, often demonstrate an ability to count up to at least three, necessary for tasks like retrieving multiple downed birds.

Basic arithmetic is within reach. Studies using preferential viewing (measuring how long dogs stare at unexpected outcomes) suggest dogs can perform simple addition and subtraction (e.g., understanding that 1 + 1 should equal 2). They show surprise when the outcome doesn't match the expected number. This ability may have evolved to help wild canines track pack members or pups.

6. Dogs Dream About Their Daily Activities

During the course of a dream episode, these dogs actually began to execute the actions that they were performing in their dreams.

Brain activity suggests dreaming. Dogs' brains show similar electrical patterns and sleep stages to humans, consistent with dreaming. Research on rats, whose brains also show similar patterns, indicates they recall and process daily activities during sleep.

Dreams reflect dog life. By temporarily disabling the part of the brain that suppresses movement during sleep, scientists observed dogs acting out their dreams. A pointer might search and go on point, a Springer Spaniel might flush a bird, and a Doberman might confront a dream intruder.

Dream frequency varies by size. You can spot dreaming by observing shallow, irregular breathing, muscle twitches, and eye movements behind closed eyelids (REM sleep). Interestingly, smaller dogs tend to have more frequent, shorter dreams, while larger dogs have fewer, longer dreams.

7. Dogs Can Learn a Surprising Number of Human Words

If my estimates were correct, then it should be possible to train a bright dog to understand two hundred words or more.

Dogs read human cues well. Dogs are remarkably adept at interpreting human body language and signals, such as pointing or glancing, often outperforming chimpanzees and young children in experimental tasks. This ability is likely a result of coevolution with humans.

Vocabulary can be extensive. While the average dog understands around 165 words, research with highly trained dogs has pushed this limit significantly. A Border Collie named Rico demonstrated understanding over 200 words, and another, Chaser, learned around 1,000 words, equivalent to a human three-year-old.

Learning requires effort. Achieving a large vocabulary in dogs requires dedicated, consistent training. This suggests that while dogs have the capacity for significant language comprehension, it doesn't develop automatically without focused human instruction.

8. Puppies Are Born Helpless and Develop Rapidly

Biologists refer to species that produce immature, dependent offspring as “altricial”—a word derived from the Latin root meaning “to nurse,” “to rear,” or “to nourish.”

Puppies are born altricial. Unlike precocial animals (like calves) born ready to run, puppies are born highly immature and dependent. Their eyes and ear canals are closed, and critical organs, including the brain, are still developing. This is a trade-off for a shorter gestation period, allowing the mother to return to hunting sooner in the wild.

Sensory development is gradual. Eyes typically open around two weeks, initially appearing blue due to incomplete pigmentation (Rayleigh scattering). Full vision and mature eye color develop over the next couple of months. Ear canals open around the same time, and hearing quickly becomes acute.

Early behaviors serve survival. Puppies sleep in piles for warmth, as they cannot regulate their own body temperature initially. They go limp when picked up by the scruff, an instinct that facilitates transport by the mother. Mother dogs lick pups to stimulate elimination and then consume waste to keep the den clean, an instinct that aids housebreaking later.

9. Older Dogs Can Suffer from Cognitive Decline Similar to Alzheimer's

This equivalent to Alzheimer’s disease in dogs is called Canine Cognitive Dysfunction Syndrome.

Brain changes with age. As dogs age, their brains become smaller and lighter, primarily due to the breakdown of connections between nerve cells. Chemical changes, including decreased mitochondrial efficiency and the accumulation of amyloid protein deposits, also occur.

Amyloid plaque impacts function. Similar to Alzheimer's in humans, the buildup of waxy amyloid plaque in the brain is linked to cognitive impairment in older dogs. Higher plaque levels correlate with poorer memory and learning difficulties, especially with complex tasks.

Symptoms follow the DISH acronym. Canine Cognitive Dysfunction Syndrome manifests through noticeable behavioral changes:

• Disorientation: Staring blankly, getting lost in familiar places, not responding to commands/name.
• Interaction changes: Less interest in petting, greeting, or seeking attention.
• Sleep changes: Sleeping more during the day, less at night, wandering.
• House soiling: Forgetting housebreaking, having accidents indoors.
  Recognizing these signs is crucial for seeking veterinary care, as treatments and environmental enrichment can help manage the condition.

10. Dogs Offer Significant Physical and Psychological Health Benefits to Humans

They found that the person’s blood pressure lowered, heart rate slowed, breathing became more regular, and muscle tension relaxed—all signs of reduced stress.

Dogs reduce stress physiologically. Interacting with a friendly, familiar dog triggers an automatic stress response reduction in humans. Studies show petting a dog lowers blood pressure, slows heart rate, regulates breathing, and relaxes muscles, often within minutes.

Stress hormone levels decrease. Research confirms that interaction with dogs leads to lower levels of stress-related hormones like cortisol. These effects are immediate and can be more rapidly effective than some anti-anxiety medications.

Long-term health benefits. Owning a dog is associated with improved cardiovascular health. Studies show pet owners tend to have lower blood pressure and cholesterol levels, even when accounting for lifestyle factors. Dogs encourage exercise through walks and play, further contributing to physical well-being and potentially increasing longevity.

Last updated: May 31, 2025