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Surprising Dog Facts: Senses, Behavior, and World Records

Linda Crampton is a writer and former science teacher with an honors degree in biology. She enjoys writing about science and nature.

A young Bernese mountain dog

A young Bernese mountain dog

Wonderful Pets

Many people think that their dog is the cutest, cleverest, most affectionate, or greatest dog in the world—and of course, they’re right! Dogs can develop a wonderful relationship with humans. Although their thinking capacity is not as advanced as ours, dogs have some abilities that surpass those of humans. They are also more intelligent than many people realize. In this article, I describe some impressive canine abilities and world records.

In addition to being our friends and beloved members of our family, dogs can be trained to help us and seem eager to do so. For example, they can help people with hearing, vision, or movement problems. Some dogs can detect specific diseases and disorders, including some types of cancer, an approaching seizure in someone with epilepsy, and low blood sugar in a diabetic person.

I’ve had dogs as companions since I was a child. All of them have been much loved. The photographs in this article include pictures of the present dogs in my family as well as some of my past ones.

Sam with his head resting on my foot

Sam with his head resting on my foot

Sense of Smell

  • A dog's most important sense is their sense of smell, which is far more advanced than ours. A human’s nose contains around 5 to 6 million olfactory (smell) receptors; a dog’s nose contains from 125 million to 300 million olfactory receptors, depending on the breed.
  • In general, the breed with the largest number of smell receptors is the bloodhound, although individual dogs of another breed may have a better sense of smell than an individual bloodhound.
  • Smells are interpreted in the brain. The area of a dog’s brain that deals with odors is about forty times larger than the corresponding area in the human brain (in proportion to the total size of the brain).
  • We know that dogs can detect the scents given off by specific people and can be used for tracking. Specially trained dogs can smell humans buried in avalanches and disaster zones. Some can detect drugs or explosives using their sense of smell.

Detecting Medical Problems in Humans

In experiments, some dogs have detected specific types of cancer in the human body by smelling chemicals in a person's breath, urine, or stool. The hope is that trained dogs will be able to discover the disease in its early stages when it has the best chance of a cure. Once researchers identify the chemicals that the animals are responding to, they may be able to create a device that detects the chemicals.

Certain dogs can tell when a person is about to have an epileptic seizure, although researchers are not sure whether the animals are using their sense of smell or detecting some other signal to inform them of the imminent seizure. Owners report that their dog’s warning behavior gives them time to get to a safe place and prepare for the seizure. The warning behavior may include the dog pawing their owner, pushing the person so that they sit down, or standing still and staring at the person. The owner learns to recognize their dog's particular warning.

Some dogs have also been able to detect low blood sugar in diabetics or an approaching migraine or heart attack. They are thought to be able to detect chemicals or chemical changes in a person's sweat, which indicate that the person is in trouble, but they may also be responding to changes in a person's behavior.

A beagle enjoying the water

A beagle enjoying the water


  • Dogs can see better in dim light than humans because their retina (the light-detecting layer at the back of the eyeball) contains more rod cells than ours. The rod cells detect shades of grey and need less light to function than the cone cells, which detect color.
  • A common misconception is that dogs see only shades of grey. In fact, their retinas contain cones and they can see some colors.
  • A human retina contains three types of cones. The retina of a dog contains only two types of cones. Therefore dogs are unable to distinguish as many colors as humans can.
  • Researchers think that a dog sees shades of grey, brown, yellow, and blue.
  • Dogs are apparently unable to distinguish colors in the red to green range in the visible light spectrum. These colors are thought to look like a shade of grey or yellow to them.
  • A red toy on green grass would probably be hard for a dog to see, since the toy would likely blend into the background.
Dylan is our Leonberger. In this picture he's a puppy.

Dylan is our Leonberger. In this picture he's a puppy.

Sense of Hearing

  • The higher the frequency of a sound, the higher its pitch.
  • Humans hear sounds with frequencies of about 20 Hz (Hertz) to 20,000 Hz, although the range varies slightly in different people. Older people tend to lose the ability to hear the higher frequencies of sound.
  • Dogs hear sounds with frequencies of approximately 40 Hz to 46,000 Hz (and perhaps a little higher in some cases), so they can hear ultrasonic sounds. These are very high pitched sounds that we are unable to detect without special technology. As in humans, the frequency range heard by dogs varies slightly in different animals.
  • Dogs have far more muscles to move their ears than humans do, which helps them to locate the source of a sound.
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Read More From Pethelpful


Although dogs aren't as mentally capable as humans, researchers are discovering that they are more intelligent than was previously thought.

According to Dr. Stanley Coren, a canine researcher at the University of British Columbia, dogs have the intelligence of a two-year-old human child. He says that they can understand about 165 "words" (in the form of spoken words or gestures) and that the most intelligent ones can understand up to 250 words. Dr. Coren also says that a border collie named Rico understood 200 spoken words.

In addition, Dr. Coren says that dogs can count up to four or five. They can also do very basic arithmetic. They know that 1 + 1 = 2 but doesn't equal 1 or 3, for example.

Assistance Dogs

Assistance dogs may be guide dogs for visually impaired people, hearing dogs for hearing impaired people, or service dogs to help people with mobility, medical, psychiatric, or behavioral problems.

Medical response dogs may be trained to respond to their owner's low blood sugar or upcoming seizure or to bring medications or the telephone to their owner. They may even be trained to trigger a specially adapted phone to dial 911 (the emergency phone number in North America). They can bark to attract someone's attention, help to reorient a person after a seizure, and carry health information for medical personnel.

Service dogs can help people with limited mobility by opening and closing doors, turning lights on and off, fetching, transporting, and depositing objects, pulling wheelchairs, opening and closing cupboards and drawers, carrying messages to caregivers in other rooms, and helping a person balance as he or she walks. They can also help to remove clothing and pull a blanket up or down over their owner when the owner is in bed. They can even move paralyzed arms or legs back into their correct positions.

Sam and Scala sleeping in the car after a long and enjoyable hike

Sam and Scala sleeping in the car after a long and enjoyable hike

More Dog Facts

  • The normal heart rate of a resting dog is 70 to 160 beats per minute, depending on the size and fitness of the dog. Larger breeds have lower heart rates than smaller breeds. An adult human's resting heart rate is around 60 to 100 beats a minute.
  • A dog's normal body temperature is about 101 degrees Fahrenheit (38 degrees Celsius), compared to 98.6 degrees Fahrenheit (37 degrees Celsius) in a human.
  • Dogs do sweat, but they do this mainly through the pads of their paws. Their panting helps to cool them down when they are hot.
  • Individual dogs may favor the use of either the left front paw or the right front paw to touch or move objects. These dogs exhibit "handedness", just as humans do.
  • A dog has three eyelids—an upper and lower eyelid like humans, plus a third eyelid called the nictitating membrane.
  • The nictitating membrane is opaque and moves over the eye in a horizontal direction instead of in a vertical direction.
  • At rest, the nictitating membrane is located in the inner corner of the eye, in front of a tear duct.
  • When a dog blinks, the nictitating membrane transports lubricating tears over the eye.
A Siberian husky with heterochromia (eyes of two different colors)

A Siberian husky with heterochromia (eyes of two different colors)

Siberian huskies are prone to heterochromia. The condition arises due to a genetic variation. It doesn't affect the dog's vision.

Dog World Records

The following statistics have been reported by Guinness World Records and were current when this article was last updated. Sadly, dogs have a much shorter maximum lifespan than humans, so the record holders change fairly frequently. Sometimes Guinness changes the awards that it offers. There may be even more impressive records than the ones described below, but they haven't been officially recorded.

  • Until 2011, the world’s oldest living dog was Pusuke from Japan, who was born on April 1st, 1985. Pusuke died on December 5th, 2011, at the age of 26.
  • On March 16th, 2022, the record for the oldest dog was awarded to TobyKeith, a chihuahua from the United States. He was 21 years 66 days old at that time.
  • The longest lived dog ever was Bluey, an Australian cattle dog. His lifespan was 29 years and 5 months. Bluey died in 1939.
  • Until 2011, the tallest dog was Giant George, a Great Dane. He was 43 inches tall (measured from paws to shoulder).
  • George weighed around 245 pounds and slept alone on a queen sized bed. He was born on November 17th, 2005, and died on October 17th, 2013, shortly before his eighth birthday. At the time of his death, he was living in Arizona.
  • In 2011, the Guinness tallest dog award was transferred to Zeus, also a Great Dane, who was 44 inches tall. Zeus lived in Michigan. Unfortunately, he died in 2014 at the age of five. He still holds the record for the tallest dog ever.
  • There are photos of larger dogs than George and Zeus circulating on the Internet, but their sizes have not been officially recognized. In at least one case, the dog's photo was found to have been digitally altered to make the dog appear larger than he or she really was.
  • In December 2016, the record for the world's tallest living male dog was awarded to Freddy. He was yet another Great Dane and lived in Britain. Freddy was 3 ft 4.75 in tall from paws to shoulder. Sadly, he died in January, 2021.
  • In April, 2021, the tallest male dog award was presented to a Great Dane named Atlas from the United States. He was 3 ft 4.5 inches tall. Unfortunately, he has presumably died because the award for tallest male dog is currently open.
  • Lizzy, a female Great Dane, was given the award for the world's tallest female dog in 2016. She was 3 ft 1.96 tall. Sadly, like Atlas she has presumably died because the award for tallest female dog is open.
Misha, my Labrador retriever

Misha, my Labrador retriever

Some More Dog Records

  • The smallest living dog in height in recent times was Milly (or Miracle Milly), a female chihuahua who was 3.8 inches tall. She lived in Puerto Rico and was born in 2011. Guinness seems to have eliminated the record for the smallest dog in height.
  • The last shortest living dog in terms of length was Heaven Sent Brandy, another female chihuahua. She was six inches long from her nose to the tip of her tail. Brandy lived in Florida and was born in 2003. I’ve used the past tense to describe her because according to the Guinness website the record is now open.
  • The dog with the longest ears is Lou, a black and tan coonhound. Each ear is 13.38 inches long.
  • The largest recorded litter of puppies is 24. The puppies were born on November 29th, 2004. Their mother was Tia, a Neapolitan Mastiff. There were nine females and fifteen males in the litter. Unfortunately, not all of the puppies survived.
  • The oldest known breed of dog is the Saluki. According to Guinness World Records, the Saluki first appeared as a distinct breed around 329 BC. Ancient art suggests that the breed or its immediate ancestor may have existed thousands of years before this, however. The dog was kept and respected by the royal family of Ancient Egypt, who mummified it after death.
  • The fastest speed at which a dog can run is difficult to determine, since it depends on the distance traveled. The fastest dog breed is generally thought to be the greyhound, which is said to be able to run at up to 45 miles an hour.

The Saluki has long legs, a slender body, and a long and narrow head, like a greyhound. It also has floppy ears. The breed has a variety of colors.

All Dogs Can Be Winners

A well-trained dog is a great pet and a great friend. Reading about statistics and achievement records is interesting, but dog owners know that their pet doesn’t need to set a world record in order to be a top dog. In some cases, winning a world record may not be desirable, depending on the nature of the award. Dogs are interesting and impressive animals that can be affectionate and wonderful members of the family.


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2011 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on September 17, 2018:

I got my latest dog from a lady who lives near me who had a litter of puppies.

Megan on September 17, 2018:

were did you get your dog

Linda Crampton (author) from British Columbia, Canada on October 19, 2011:

Thanks a lot for the comment and vote, Eiddwen. I love dogs and I love writing about them!

Eiddwen from Wales on October 19, 2011:

What a great hub and I have to vote up up and away here.

thank you so much for sharing.

Take care and have a great day.


Linda Crampton (author) from British Columbia, Canada on October 13, 2011:

Thank you so much for the comment and the votes, and for sharing the hub, vocalcoach! I love dogs too, and I love to learn new information about them.

Audrey Hunt from Pahrump NV on October 13, 2011:

I can't begin to tell you how much I enjoyed this hub. I am a dog lover - in fact I prefer dogs to people :) Wonderful facts. Thanks for all the research. I will FB this and will also forward on to friends. Voted up and across. vc

Linda Crampton (author) from British Columbia, Canada on August 14, 2011:

Thanks you very much for the comment and the rating, paradigmsearch! I appreciate them both.

x on August 14, 2011:

This is an extremely well researched and knowledgeable article. Many thanks! Rated up here, there, and everywhere. :-)

Linda Crampton (author) from British Columbia, Canada on May 07, 2011:

Thank you very much, daisyjae.

daisyjae from Canada on May 07, 2011:

I like your hub, lots of interesting info on dogs. Cute pics too.

Linda Crampton (author) from British Columbia, Canada on April 25, 2011:

Thank you for the comment, James. Yes, dogs are great!

James A Watkins from Chicago on April 25, 2011:

I so enjoyed this awesome article. I love dogs! Aren't they great? :D

Linda Crampton (author) from British Columbia, Canada on April 25, 2011:

Hi, tonymac04. Thank you very much for your comment. Best wishes to you, too.

Tony McGregor from South Africa on April 25, 2011:

Wonderful and fascinating Hub. Found the cancer detection ability very interesting indeed.

Love and peace


Linda Crampton (author) from British Columbia, Canada on April 23, 2011:

Thanks for the comment, Just Ask Susan. Yes, Ryan and Scala are Leonbergers. Scala and Sam are unfortunately no longer alive, but Ryan and Misha are.

Susan Zutautas from Ontario, Canada on April 23, 2011:

Alicia I enjoyed your hub very much. I have to ask is Ryan and Scala Leonbergers?

Linda Crampton (author) from British Columbia, Canada on April 17, 2011:

Thank you very much for the comment and the vote, Ingenira. I think dogs are extraordinary too!

Ingenira on April 17, 2011:

Amazing information about dog ! Wow !

Dog can detect chemicals or chemical changes in a person's sweat, and how sick he is. That's really extra-ordinary. Voted up and awesome !

Linda Crampton (author) from British Columbia, Canada on April 16, 2011:

Hi, Prasetio. Thanks for the visit and the rating. I hope that you have a nice weekend too!

prasetio30 from malang-indonesia on April 15, 2011:

This was really useful information. I don't know about dog's behavior. Thanks for writing this. You always teaching us new and interesting things. Rated up. Have a nice weekend!


Linda Crampton (author) from British Columbia, Canada on April 12, 2011:

Thank you very much for the comment and the vote, marcoujor! It's great to hear from other dog lovers. I agree with you - dogs are wonderful animals.

Maria Jordan from Jeffersonville PA on April 12, 2011:

How intuitive to be able to detect the forewarning signs of a seizure... dogs are so utterly amazing and lifesaving.

Thank you, Alicia~~ this was great~~ Voted USEFUL & UP!

Linda Crampton (author) from British Columbia, Canada on April 12, 2011:

Hi, Chatkath. I think dogs are amazing too! Perhaps they have other interesting abilities which we haven't discovered yet. Thanks for the comment.

Kathy from California on April 11, 2011:

Great Hub Alicia, Dogs are so amazing, I recently saw a show on their ability to detect cancer too, what an incredible animal! And they have also solved so many cases, with their ability to track and smell. What would we do without them? Thank you so much for sharing.

Linda Crampton (author) from British Columbia, Canada on April 11, 2011:

Kashmir56 - Thank you very much for the visit and the vote!

GetSmart - Hi! I've read that other animals, such as parrots, exhibit handedness too. It's a very interesting topic to study. Thanks for the comment.

Hi, Simone. Thanks for commenting! It certainly is interesting that some dogs can smell cancer. I hope scientists soon discover what chemicals the dogs are responding to. Hopefully this discovery will help us understand cancer better, which might then enable us to develop better treatments.

Thanks for the visit and the comment, b. Malin. Yes, it's amazing what dogs can do!

b. Malin on April 11, 2011:

Wonderful Hub and Pictures, and who doesn't love a Dog...I had heard about Dogs that are able to smell Cancer on certain individuals, long before the Doctors are aware.

Simone Haruko Smith from San Francisco on April 11, 2011:

Absolutely fascinating, AliciaC! I am especially intrigued by the cancer smelling ability. Dogs are amazing!

GetSmart on April 11, 2011:

Great hub! I always knew one of my dogs was right pawed, my son found my belief to be quite funny though. I will be showing him this when he comes over to visit. Thank you for this information!

Thomas Silvia from Massachusetts on April 11, 2011:

Hi AliciaC, great well put together hub on dog facts !

Vote up !!!

Linda Crampton (author) from British Columbia, Canada on April 11, 2011:

Thank you very much, Fossillady. It is wonderful how dogs can help us as well as be our companions.

Kathi Mirto from Fennville on April 11, 2011:

Wow, you have assembled a lot of dog facts! Amazing work which can provide an excellent reference. Especially when we can't remember half this stuff when we need I saw a documentary on dogs that detect cancer. They are amazing animals with sweet souls! Thanks for sharing Alicia

Linda Crampton (author) from British Columbia, Canada on April 11, 2011:

Thank you, kafsoa. It's nice to meet you!

kafsoa on April 11, 2011:

This is a nice hub about dogs and nice video too:)

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