Surprising Dog Facts: Senses, Behavior, and World Records
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 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 dogs.
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.
- 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 cannot 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 be hard for a dog to see, since the toy would blend into the background.
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, 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.
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 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). 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.
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.
Siberian huskies are prone to heterochromia. The condition arises due to a genetic variation. It doesn't affect the dog's vision.
How many dogs have you owned?
Dog World Records
The following statistics have been reported by Guinness World Records and are current as of mid 2017. There may be even more impressive records than these, 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.
- Since Pusuke's death, there hasn't been an officially recognized oldest living dog.
- 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 dog was awarded to Freddy. He is yet another Great Dane and lives in Britain. Freddy is 40.75 inches tall from paws to shoulder.
Some More Dog Records
- The smallest living dog in height is Milly, a female chihuahua who is 3.8 inches tall. She lives in Puerto Rico.
- The smallest living dog in terms of length is Heaven Sent Brandy, another female chihuahua. She is six inches long from her nose to the tip of her tail. Brandy lives in Florida.
- The dog with the longest ears is Harbor, a black and tan coonhound. His left ear was 12.25 inches long and his right ear was 13.5 inches long on June 8, 2010.
- 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 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 dog 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!
Dogs' Dazzling Sense of Smell from PBS (Public Broadcasting Service)
Dogs have color vision from the Smithsonian Magazine
Hearing range in animals from the University of Calgary
American Psychological Association. (2009, August 10). Dogs' Intelligence On Par With Two-year-old Human, Canine Researcher Says. ScienceDaily. Retrieved July 25, 2017 from www.sciencedaily.com/releases/2009/08/090810025241.htm
The Psychology Today magazine describes Dr. Coren's report on the ability of dogs to solve very basic math problems.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
© 2011 Linda Crampton