Dogs use their noses to read their surroundings, notice subtle changes in our body language and learn the names of specific toys. At the same time, there is still a lot we do not know for certain about how they experience the world.
Here are 30 facts about dogs, from familiar habits to less obvious research findings. Some studies include only a few dogs or use controlled experiments, so we distinguish between what research has shown and what it cannot yet establish.
1. The nose gathers information
For a dog, scent is a way to find out who has been somewhere, what has passed by and which scent trails remain. A walk around the neighbourhood can therefore contain far more information for a dog than for the person walking beside it.
That is one reason sniffing is not just a pause during a walk. It is an important part of how dogs explore their surroundings.
2. Dogs hear higher-pitched sounds than we do
Dogs can hear higher frequencies than people. A high-pitched sound that seems to come from nowhere may therefore be easy for a dog to hear.
Dogs can also move their ears in different directions to work out where a sound is coming from. This may explain why your dog sometimes reacts before you have heard anything.
3. Dogs can detect weak thermal radiation
A dog’s hairless nose tip may have a function beyond smell. In a controlled experiment, three trained dogs could detect weak thermal radiation from an object. The study suggests that they registered the information through touch rather than sight.
This is an interesting but preliminary finding from a small experiment. It does not mean that dogs see heat like a thermal camera. Read the study abstract on PubMed.
4. Canine intelligence has several sides
A dog that learns commands quickly is not necessarily “smarter” than one that needs more time. Dogs can be good at different things: following scent trails, working with people, solving problems or working independently.
What we call intelligence also depends on the task a dog is given – and what it is motivated to do.
5. Sniffing is part of the walk, not a detour
When a dog stops at a patch of ground or a lamppost, it is investigating scent trails left by other animals. We cannot read the same information with our eyes.
A walk with time to sniff lets a dog explore at its own pace. That can be more stimulating than covering the same route as quickly as possible.
6. Smell affects how food tastes
Dogs have fewer taste buds than people, but smell plays a major role when they investigate food. A food’s aroma can affect how appealing it seems before the dog has even taken a bite.
That also helps explain why a dog may be more interested in food with a strong smell, even if it does not taste particularly strong to us.
7. Sleep may support learning
Dogs have sleep stages that resemble those of humans, and movements or little sounds during sleep may be linked to dream-like activity. Still, we cannot know what a dog is dreaming about.
A more specific research finding relates to learning. EEG studies have examined dogs’ sleep activity and found a connection between certain sleep patterns and learning outcomes. This does not prove that a nap by itself teaches a dog a new command, but sleep seems to play a role in how memories are processed. Read the study on PubMed.
8. A wagging tail does not always mean happiness
A wagging tail shows that a dog is engaged or aroused, but it does not tell you on its own whether the dog is happy, uncertain or tense. Look at the dog’s posture, face and ears too, and notice whether its movements are loose or stiff.
In one study, dogs wagged differently depending on the emotional signal they encountered. The finding is interesting, but it does not provide a simple code for interpreting every dog’s tail. Read the study on asymmetric tail wagging.
9. Puppies are born with their eyes and ear canals closed
Newborn puppies have closed eyes and ear canals. During their first weeks, they depend on their mother and on the senses that already work, especially smell and touch.
Sight and hearing develop after birth. Do not try to open a puppy’s eyes or ear canals yourself. Let development happen naturally, and contact a vet if something seems wrong.
10. Some dogs eat faeces
Eating faeces is called coprophagia. It can occur in puppies exploring the world, but also in adult dogs. Habits, access and environment may all play a part; there is no single explanation that applies to every dog.
If an adult dog suddenly starts doing this, or the behaviour becomes recurring, it is a good idea to speak to a vet. The same applies if the dog develops other symptoms at the same time.
11. Whether dogs feel jealousy is still debated
A dog may push between its owner and someone else, or try to get attention when the owner turns away. It is easy to call this jealousy, but research does not offer a simple answer.
A 2014 study observed attention-seeking behaviour when owners gave attention to a toy dog. A later study found no clear evidence that the reactions were caused by jealousy. It is more accurate to describe what we see – such as competition for attention – without claiming to know exactly what the dog feels. The 2014 study and the 2018 follow-up study show why the topic is still debated.
12. Dogs do not see only in black and white
Dogs have dichromatic colour vision. They distinguish blue and yellow shades particularly well, while red and green do not appear to them as they do to people.
This can be useful to remember when choosing toys: a blue toy may be easier for a dog to see in green grass than a red one.
13. Yawning can have several causes
A dog may yawn because it is tired, but also in situations that make it uncertain or excited. One yawn is not enough to tell how a dog is feeling.
Notice what is happening around the dog and pay attention to the rest of its body language. Repeated yawning alongside a tense body or attempts to move away may tell you something about the situation. To learn more about how anxiety can show up in dogs, read our guide to separation anxiety in dogs.
14. Dogs also read body language when they meet
When dogs meet, they notice how the other dog moves, stands and approaches. A stiff body and a soft, curved approach can communicate very different things.
Scent provides more information, but visible signals matter too. Give dogs enough space to greet each other or move away rather than keeping them close when they seem uncomfortable.
15. Sniffing another dog’s rear is social information-gathering
Dogs investigate each other’s scents when they meet. The area around the rear carries scent information, and sniffing is part of how dogs explore one another socially.
That does not mean every dog wants to greet for long. If a dog tries to move away, becomes stiff or hides behind its owner, let it end the interaction.
16. Resting heart rate varies with size
A dog’s heart rate is affected by size, age, activity, stress and health. Small dogs often have a higher resting heart rate than large dogs, so one number does not suit every dog.
If you are concerned about your dog’s heart rate, breathing or general condition, look at the bigger picture and contact a vet rather than interpreting one number on its own.
17. Dogs sweat, but mainly cool themselves by panting
Dogs have sweat glands, including in their paw pads, but they regulate their body temperature mainly by panting. Sweating through the paws therefore plays a more limited role than sweating does in people.
Panting after exercise or on a warm day can be normal. Heavy panting alongside lethargy, unsteadiness or confusion may be a sign of overheating and needs prompt attention.
18. Whiskers register touch
The whiskers around a dog’s nose and eyes are sensitive sensory hairs, not just longer fur. They register touch and movement close to the face.
That is a good reason to leave them alone. Do not trim a dog’s whiskers unless a vet or another qualified professional has a specific reason to recommend it.
19. Trained dogs detected stress samples by smell
In a controlled experiment, trained dogs could distinguish between scent samples taken from people before and after a stressful task. The samples consisted of breath and sweat, and the dogs had been trained to identify the stress sample.
This is an interesting finding, but it does not mean every family dog always understands our emotions. The study tested trained dogs’ ability to distinguish between specific samples in a controlled situation. Read the study in PLOS ONE.
20. A few dogs learn many words
Many dogs learn words such as “sit”, their own name and cues related to walks or food. A small group of dogs has shown an unusual ability to learn the names of many different toys.
Researchers call these dogs “Gifted Word Learners”. They are rare, and this finding does not mean every dog can learn hundreds of object names. It does show how much individual dogs can differ in what they learn.
21. Dogs can distinguish between facial expressions
In a controlled task, dogs could distinguish between different emotional expressions on human faces. This suggests that they can use visual information from a face, not just a person’s voice or the situation around them.
It does not mean that dogs interpret faces exactly as people do or know precisely why we feel the way we do. The study shows that expressions can serve as signals for dogs. Read the study on PubMed.
22. Digging can serve several purposes
A dog may dig to investigate a scent, follow a hunting instinct, play or make a cooler place to lie down. Some dogs also dig to bury things.
If digging starts suddenly or becomes intense, it may be worth noticing when and where it happens. The pattern often tells you more than the hole itself.
23. A full-body shake does more than remove water
After a bath or a rainy walk, a dog shakes to remove water from its coat. Dogs may also shake themselves after an intense or unfamiliar situation.
A shake can mark a clear transition after an event, but it does not prove on its own that the dog was stressed. Look at the situation and the other signals the dog is showing.
24. Dogs have a third eyelid
Dogs have a nictitating membrane, often called the third eyelid, in the inner corner of the eye. It helps protect the eye and spread tear fluid.
If the membrane suddenly becomes visible, or if the eye is red, swollen or watering, the dog should be checked by a vet.
25. A dry nose does not automatically mean illness
A dog’s nose can be dry or moist at different times of the day. Sleep, temperature, humidity and licking can all affect how it feels.
A dry nose on its own is not a reliable way to check for a fever. Instead, look for changes in your dog’s appetite, energy, breathing and behaviour, and contact a vet if your dog seems unwell.
26. Smell helps dogs recognise you
Dogs use scent to recognise people and other animals. They can recognise a familiar smell even when the person is out of sight.
That is one reason dogs investigate clothes, shoes and other things that have been in contact with people they know.
27. Dogs of the same breed can be very different
A breed can give you an idea of the traits a dog may have been bred for, but it does not tell you everything about an individual. Two dogs of the same breed may react differently to strangers, sounds, play and new situations.
Genetics, upbringing, experience, health and environment all interact. It is more useful to get to know the dog in front of you than to expect it to fit a breed stereotype.
28. Head tilting has been studied in a toy-naming task
One study examined dogs’ head tilts when their owners asked them to fetch toys by name. The few dogs that were especially good at learning toy names tilted their heads more often during the task than dogs without the same word-learning ability.
The study does not explain why your dog tilts its head when you talk to it in everyday life. It shows a connection in one specific task, not a universal explanation for head tilting. Read the study in Animal Cognition.
29. Play gives dogs a chance to practise
Play can give dogs the chance to practise movement, timing and social interaction. During play between dogs, roles may change, and the dogs may pause before continuing.
Notice whether both dogs choose to return to play. If one tries to move away, let it do so.
30. Dogs and people share a long history
Dogs have lived alongside people for thousands of years. Throughout history, they have worked with us in many ways – as hunting dogs, guard dogs, herding dogs and companions. During the Viking Age, dogs were sometimes buried with people.
This long history is part of the reason dogs pay such close attention to human signals. But dogs are still dogs: they have their own senses, needs and ways of understanding the world around them.
Frequently asked questions about dogs
Do dogs dream?
Dogs have sleep stages associated with dream-like activity, and some move their paws or make small sounds while asleep. We cannot know for sure what they dream about.
What colours can dogs see?
Dogs have dichromatic colour vision. They distinguish blue and yellow shades better than red and green.
Why do dogs sniff so much?
Smell gives dogs information about places, people and other animals. Sniffing is therefore an important part of how they explore the world.
Does a wagging tail mean a dog is happy?
Not necessarily. Read the tail together with the dog’s posture, facial expression and the situation it is in.
Is a dry nose a sign that a dog is ill?
Not by itself. A dog’s nose can be dry for several normal reasons. Look at the dog’s overall condition and contact a vet if it seems unwell.
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