Reviewed by Amy Flowers, DVM on December 17, 2020

Fact: Dog Kisses Can Make You Sick


Think dogs' mouths are cleaner than humans? Think again. Dogs' chops are teeming with bacteria and parasites and may harbor germs like salmonella and campylobacter. These organisms get into a dog's mouth from eating spoiled food or when they use their tongue as toilet paper. Then a kiss moves these germs from pooch to person, potentially along with a nasty case of diarrhea.

Fact: Humans Can Make Pets Sick


It's not common, but it happens. H1N1 "swine" flu has hit cats, dogs, and ferrets -- contracted from their sick owners. Most often it's mild, but a few pets have died, so vets advise frequent hand washing and separate beds when the owner is sick. Dogs and people can also share the same strains of E. coli bacteria. And MRSA, the "superbug," can move between humans and dogs.

Myth: Cats Steal a Baby's Breath


This superstition goes back to the 1700s. When babies died of sudden infant death syndrome (SIDS), people were quick to blame a cat seen lying in the crib. Today, soft toys, illnesses, a stomach-lying position have all been linked to SIDS -- but not cats. Cats are drawn to cribs because they're warm, cozy, elevated places -- perfect for a catnap.

Fact: Dogs Can Smell Hypoglycemia


It sounds like a Lassie TV episode, but it's truth, not fiction. Dogs can sniff out a dangerous drop in blood sugar in a diabetic owner and alert the person to take action by pawing, licking, whining, or barking. Some dogs have even been trained and placed as diabetic service dogs. Their nose for hypoglycemia (low blood sugar) is correct 90% of the time, according to their trainers.

Fact: Dogs Have a Look of Love


When your dog locks eyes with you, it may genuinely be a look of love, and not simply a form of begging. Dogs can develop this atypical behavior with close human companions -- while between dogs or with a strange person, a direct stare is a threat. Of course not every glance from Fido is loving -- they may simply want your dinner. Or, if their body is tense and ears flattened, they may be telling you to back off.

Fact: Cats May Love Too Much


Behavior experts confirm that some cats really do experience separation anxiety when apart from a favorite person -- and that's one reason a sweet kitty may pee on your clothes when you're at work. Other signs: the cat paces, vocalizes, or blocks the owner's path to the door. Left alone, they may vomit or be too worried to eat. For cats who love too much, behavior therapy can help -- along with anti-anxiety medications for severely affected cats.

Fact: Dogs Can Learn 250 Words


The smartest, best-trained breeds are similar to a 2-year-old child in their ability to understand human speech, according to researcher Stanley Coren, PhD. These dogs understand up to 250 words, while the average dog can understand 150 words.
Top Dog: Border collie, poodle, German shepherd, golden retriever, Doberman pincher.
Beauty Before Brains: Borzoi, chow chow, bull dog, basenji, Afghan hound.

Fact: White Cats Are Often Deaf


Cats with a white coat are often deaf in one or both ears, especially those with blue eyes. When only one eye is blue, the cat is likely to be deaf on that side only. Many owners report that deaf cats are not too bright -- but it's not clear if deafness or lower intelligence is to blame.

Myth: Cats Will Land on Their Feet


Cats are champs at landing feet first over short distances, thanks to a highly flexible backbone. But they do sometimes land on their heads. And beyond one or two stories, their feet cannot "break" the fall. Their heads and bodies collide with the ground, causing severe injuries. Cats with access to an elevated, open window may also focus so intently on a bird, that they lose their balance and fall -- called high-rise syndrome.

Fact: Dogs Can Dance


Dog lovers have created a competitive event called canine freestyle that brings the bond between human and animal to a new high. A dog and handler pair up -- ballroom dancing style -- for a choreographed dance performed with music and, sometimes, matching costumes.

Fact: Cats Smell With Their Mouths


Cats have a small scent gland in the roof of the mouth called the vomeronasal organ. For a really good whiff of something like urine or another cat's private parts, they'll open their mouths wide to draw the odor to this scent organ. This fierce-looking behavior is called the Flehmen reaction, and it's often seen in males who are checking out a female cat in heat.

Myth: Tail Wagging, Happy Dog


Dogs wag their tail in three very different moods and only one is happy. When it's unusually high and stiff, the dog is agitated and ready to protect their turf. A tail held low and wagged very quickly shows a scared and submissive dog. Happy dogs wag their tail in their natural, mid-level position -- and their ears, mouth, and body will look relaxed, too.

Fact: Newborn Pups Don't Wag


Puppies don't wag their tails before they are about three weeks old -- and some don't start until seven weeks old. Vets believe tiny puppies are capable, but they're too busy sleeping and eating to bother. As they become more alert, tail wagging starts as a kind of sign language: a peace sign to rambunctious littermates or when begging for food. Dogs almost never wag their tails when alone.

Fact: Early Bonding Key for Kitty


Some cats that are aloof or bite the hand that feeds them probably had no exposure to people in early life. Feline behavior experts say a kitten needs regular contact with people in the first seven weeks, or it may never bond with humans. Even five minutes a day in the early weeks will teach a kitten not to bite when the hand of a towering human lifts it off the ground.

Myth: Dogs See in Black and White


Not so, say canine researchers. Dogs are like red-green color blind humans. They see dark blue, light blue, gray, light yellow, darker yellow (sort of brown), and very dark gray. They see the colors of the world as basically yellow, blue, and gray. Dogs also see better in low light and can pick up the slightest movement -- a trait that makes them good hunters. They probably do not see red, orange, or green, based on examination of the color-sensitive cone cells in canine retinas.

Myth: Warm Nose, Sick Dog


The temperature of a dog's nose changes easily and is not a good sign of illness. It can be hot and dry after lying in the sun or cool and wet from dipping into the water bowl. Better signs of illness are lethargy, loss of appetite, vomiting, coughing, or a body temperature above 102.5˚F on a rectal thermometer. The wet snout? It comes from ducts that carry tears toward the nose.

Fact: A Limp Can Mean Lung Trouble


Dogs sometimes come to the vet for a limp and leave with a diagnosis of lung cancer or some other pulmonary issue such as heartworms. Cancer in the chest can activate the leg bones to grow new tissue -- causing swelling and pain in the legs. A more typical symptom of lung cancer is a cough, although about 25% of dogs have no symptoms until cancer is detected on a chest X-ray. The leg changes -- called hypertrophic osteopathy -- can go away if the cancer is treatable.

Myth: Cats Need Milk


The long-standing myth that cats need milk is wrong and giving your pet a saucer of cow's milk could make it have diarrhea. Kittens drink their mother's milk until they are weaned and older cats may like the taste of cow's milk. But adult cats don't have much lactase, the enzyme needed to break down the lactose sugar in milk. The result is often uncomfortable and messy: diarrhea.

Myth: Dogs Need Bones


This practice comes from the idea that ancient dogs (wolves) ate plenty of bones. Today, pet dogs can get all the calcium and nutrients they need from dry kibble. Bones do satisfy the intense canine chewing instinct, but they can choke a dog or splinter into knife-like shards, even when cooked. Edible chewies or sturdy rubber chew toys from the store are a safer choice.

Myth: Licking Heals Dogs' Wounds


There is no magic healing power in dog saliva, contrary to popular belief. Quite the opposite: mouth bacteria may cause an infection that delays healing. Dogs are also prone to compulsive licking, which can result in persistent sores, called acral lick dermatitis. The healing choice is usually an Elizabethan collar that blocks their tongue from reaching a sore until it's completely healed.

Fact: Cats Kiss With Their Eyes


Cats communicate with a slow blink, according to feline experts. With their own kind, it's a peace sign, meant to put other felines at ease. Aimed at a human, this seductive blink shows affection, even love. People can return the love with a long gaze and slow blink to "blow a kiss" back in cat body language. The calming blink works on house cats, feral cats, and even tigers in the wild, according to behaviorist Roger Tabor.

Fact: Dogs Fall in Love


Can two dogs develop a loving relationship? Or do they hook up with anyone at the dog park? Anthropologist Elizabeth Marshall Thomas says dogs can fall in love and she documents a remarkable love story between "Sundog" and "Bean" in her book, "The Social Lives of Dogs." Thomas claims few dogs develop relationships because they are kept as pets in captivity, "born to do what we want, not what they want."

Fact: Smoking Kills Cats and Dogs


Secondhand smoke increases the risk of at least two fatal cancers in cats: lymphoma and oral carcinoma. Housecats get a double dose of toxins by breathing cigarette smoke in the air and by licking the residue off their fur when grooming. Dogs with long noses may develop cancerous nasal tumors from living with a smoker -- and short-nosed breeds are more prone to lung cancer.

Cat Language: Purring Through Pain


The quiet, motor-like sound of a purring cat is not yet well understood. Every cat fancier has seen their pet purring in happiness; yet cats also purr when they are in pain or close to death. It may be a self-soothing behavior. Kittens begin purring within hours of birth as they nurse -- and the mother cat purrs during feeding sessions, too.

Cat Language: Chirping


Cats make this sharp, high-pitched sound when highly aroused by the sight of prey, such as the animal more commonly known for chirping, the bird. When a cat is blocked from getting at the prey, they may chatter -- a throaty vocalization accompanied by quick movements of the lower jaw.

Dog Language: Grin and Bear It


Owners who insist their dogs can smile are correct in thinking that the canine mouth can show emotions. Relaxed and open, it can be a sign of a happy dog. A submissive grin is a canine version of our nervous smile. Dogs pull their lips up, show their front teeth, and may crouch. This harmless, nervous "grin" is easily confused with an aggressive snarl. When in doubt, don't mess with the dog.

Dog Language: Whale Eye


When dogs turn their head away, but swivels their eyes around to keep you in sight, they are displaying "whale eye," and is usually frightened or guarding something. The whites of their eyes will show in a crescent shape and disturbing them can lead to growling or snapping. A stiff body completes the tense picture. Dogs have a sideways glance for more relaxed moments, too: not much white will show and their body will look at ease.

Show Sources


1)         Andersen Ross/Brand X Pictures
2)         Martin Leigh/OSF, Hans Wretling/Nordic Photos
3)         Comstock, Gandee Vasan/Stone
4)         Steven Errico/Photodisc
5)         John Elder/The Image Bank
6)         Lynnette Henderson/Flickr
7)         Lisa McKelvie
8)         Francois Gilson/Photononstop
9)         BakkoBrats/Flickr
10)       Marla Brose/Albuquerque Journal
11)       Morales Morales/Age Fotostock
12)       Sheldon Lewis
13)       Erik Isakson/Rubberball
14)       Junku/Flickr
15)       Photo courtesy of Dana Silberman
16)       Rosseforp
17)       Kevin Horan/Time & Life Images
18)       Altrendo Nature/Altrendo
19)       Dennis Drenner / Aurora
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21)       Anna Webb/WebMD
22)       Franz Pritz/Picture Press
23)       Ted Kinsman/Photo Researchers Inc., Jupiter Unlimited
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25)       Peter Cade/Iconica
26)       Daniela Hofer/F1 Online
27)       Philip J Brittan/Photonica


American Diabetes Association: "Could a Dog Save Your Life?"

American Veterinary Medical Association: "Frequently Asked Questions about the 2009 H1N1 Flu Virus and Pets."

ASPCA: "Canine Body Language," "Cat Vocalizations," "Cats and Babies," "Compulsive Behavior in Dogs," "Factors Determining a Cat's Personality," "Feeding Your Adult Cat," "People Foods to Avoid Feeding Your Pets," "Secondhand Smoke: Silent Killer Hurst Pets, Too."

Brevitz, B. Complete Health Dog Handbook, Workman Publishing, 2009.

Byard, R. Sudden Death in Infancy, Childhood and Adolescence, Cambridge University Press, 2004.

Canine Freestyle Federation: "Canine Freestyle."

Cat Fanciers' Association: "Myths and Facts About Cats."

Cats International: "Your Cat's Tail, Ear, and Eye Signals."

CDC: "Diseases From Dogs."

Coile, C. Why Do Dogs Like Balls? Sterling, 2008.

Coren, S. How to Speak Dog, Free Press, April, 2000.

DOE Office of Science, Ask a Scientist: "Cat Eye Blinking," "Dogs and Wet Noses."

Marshall Thomas, E. The Social Lives of Dogs, Simon & Shuster, 2001. "Do Cats Always Land on Their Feet?" "High-Rise Syndrome: Cats Injured Due to Falls," "Petting-related Aggression in Cats," "Separation Anxiety in Cats," "Flehming: Smelling with an Open Mouth." "Can Dogs See in Color," "The Risks of Secondhand Smoke in Cats," "Understanding 'Cat Talk' What Is Your Kitty Saying?" "Dog Tails - Why Dogs Wag Their Tails."

Tabor, R. Cat Behavior, a Complete Guide to Understanding How Your Cat Works, Readers Digest, 1998.