9 Big Dog Myths

  • When your dog’s nose is dry, is he/she sick?
  • Do dogs eat grass to induce vomiting?
  • Can dogs only see in black and white?
  • Do dogs age seven years for each human year?

These are common legends or “old wives’ tales” that we hear over and over, but the truth is they are false. Read on to learn more about the myths, so next time it comes up in a conversation, you can set the record straight!

1. A Dry or Warm Dog Nose is a Sign of Illness

Not so; however, the origins of this myth are rooted in fact. Canine distemper is a highly contagious and deadly virus in dogs with no known cure. A symptom of advanced distemper is hyperkeratosis or a thickening of the nose and footpads, so essentially they become hard and dry. In the past, when distemper was a lot more common in dogs, it was thought that a cool, wet nose meant a dog did not have distemper. 

The truth is the temperature and moisture of your dog’s nose are not signs of good health. For example, a dog’s nose can be dry and/or warm when it wakes up from sleep. Keep in mind if your dog’s nose is persistently dry and crusty it may be a sign of a health problem, but a healthy dog can have a warm and/or dry nose and a dog that is ill can have a cold and wet nose. If your dog experiences any obvious or significant changes to the condition of its nose, you should take your baby to the vet. 

Interesting fact:  A dog keeps its nose cold and wet by licking it.

2. Dogs Have Cleaner Mouths Than Humans

This myth probably got started because dogs lick their wounds and sometimes heal faster afterwards. That said, if a dog’s wound or injury heals more quickly after the dog has licked it, that’s because the dog’s rough tongue has removed dead tissue and stimulated circulation, much like a doctor would remove debris from a human wound. On the contrary, a dog’s licking of its own wound can have the opposite effect of introducing bacteria and/or irritating the wound.

There is also a good chance this myth came from older medical literature that claimed human bites are more likely to become infected than bites from other mammals including dogs, so people assumed the dog’s mouth was the cleaner of the two. However, recent data shows that human bites occurring anywhere other than the hand are no more at risk of infection than any other type of mammalian bite. 

The truth is a dog's mouth contains germs and other yucky stuff, which is not surprising since dogs are not opposed to eating out of the garbage, off the floor and licking themselves. Plus, many dogs don’t get their teeth brushed so they have dental bacteria too. While a dog’s mouth is quite germy, the good news is the germs are usually dog-specific and have no effect on humans. So, if your dog kisses and licks your face worry not, but don’t go encouraging your Fido to lick your wounds.

Interesting fact: A dog’s tongue is not only his wash cloth but his toilet paper.

3. Dogs See in Black and White

It was once thought dogs could see only in black, white and shades of gray. There is no evidence as to what fueled this myth, but it probably started before doctors fully understood the canine eye.

The truth is, dogs can see colors but not in the same way humans do. Based on the types of cones in the canine retina, dogs probably see colors on the blue side of the spectrum best. This means dogs see primarily in blue, greenish-yellow, yellow and various shades of gray. Their vision is thought to be like red-green colorblindness in humans, meaning dogs, and to a lesser degree cats, lack green cones.

The canine color spectrum presents itself in two hues:

  • The violet to blue-violate range, probably seen by dogs as blue.
  • Greenish-yellow, yellow and red, probably seen by dogs as yellow.
  • Dogs have a narrow band in the blue-green range without color, seen by dogs as shades of gray or white.

Interesting fact:  Guide dogs are unable to differentiate among traffic signals based solely on color, so they are taught other factors such as brightness, smell, taste, and texture to help them differentiate between similarly colored objects.

4. Dogs Eat Grass to Induce Vomiting

While it is true dogs often vomit after eating a lot of grass, this does not mean they purposely ate the grass to cause themselves to vomit or to indicate they don’t feel well.

This myth is most likely because of an incorrect assumption by dog owners who witnessed their dogs eat grass and then throw-up and correlated the two.

The truth is, dogs eat grass because they like it. In fact, some dogs graze while others chomp and chew grass. When enough grass accumulates in the dog’s stomach it causes minor irritation and causes the dog to vomit. Grass will not hurt your dog unless it is chemically treated. 

Interesting fact:  Grass is a normal part of the carnivore’s diet and is usually consumed when they feed on smaller prey and consume the entire animal, meaning the grassy contents of its stomach.

5.  Dogs Age Seven Years for Every Human Year

Not true. If you do the math, this would mean that a 15-year-old dog (and plenty live to see that age) would be 105 in dog years. Not likely! This myth came from people comparing the average lifespan of a human to that of a dog and estimating that dogs age seven years for every human year.

The truth is dogs do age much faster than humans though the rate is faster early in their lives (hence the reason dogs can give birth long before they are even one year old), but that rate seems to slow down as they age. Also, the dog’s breed and size have a lot to do with its aging process and lifespan. Smaller breeds are known to live 15-20 years while larger breeds only live between 7-10 years.

Interesting fact:  Young giant dog breeds like the Great Dane and Mastiff tend to reach adulthood more slowly than the average dog despite their shorter lifespans.

6.  You Can't Teach an Old Dog New Tricks

Oh, yes you can! Just like humans can learn at any age, so can dogs. Sometimes, in both cases they just don’t want to because with age can come stubbornness in man and in dogs. This myth probably stems from the fact that older dogs often show less interest in new activities and are less responsive to training.

The truth is that while training an older pet is not as easy as training a puppy, it can be done. A senior or older dog may not hear or see as well as it did when it was younger, so it might not be as energetic or perhaps easy to please as a puppy. However, you can train an older dog. You just have to demand its attention and make sure the dog can handle the activity given its age; meaning it’s not too physically demanding for the dog to perform successfully.

Interesting fact:  Some dogs suffer from cognitive dysfunction which is essentially senility, so in those cases that will affect the dog’s ability to retain new information.

7.  A Wagging Tail Means a Happy Dog

Man walking dog

It’s not entirely accurate, but this myth is rooted in truth. Dogs do tend to wag their tails when they are happy and/or excited, but they wag their tails for lots of reasons. This myth is owing to the cultural belief that a dog wagging its tail is demonstrating that it’s happy.

The whole truth is that a dog’s body language is complex. When your dog wags its tail, it’s a means of communicating with you and showing you how it’s feeling. It is correct that tail wagging is often a sign that the dog is happy but it can also be a sign of fear, anxiety and other traits that do not have anything to do with happiness. Pay attention to a dog’s overall body language to determine its mood. 

Interesting fact:  The reason people sometimes report that a dog’s tail was wagging just before it bit someone is because the wagging tail (held high and moving back and forth rapidly) can be a precursor to aggression. 

8.  Female Dogs Should Have One Litter of Puppies Before Being Spayed

Unfortunately, this myth is often used as an argument against spaying dogs even though there is no good reason a dog should have puppies before it is spayed. Spaying a female dog and/or neutering a male is highly recommended to help control the overpopulation of unwanted pets. The belief that a female dog will somehow miss out on giving birth is 100 percent false and is a prime example of anthropomorphism.

The truth is, there are no known long-term health benefits to a female dog having a litter of puppies prior to being routinely spayed. Spaying or neutering can also prevent some life-threatening health conditions in your dog associated with the reproductive system, including cancer.

Interesting fact:  Dogs that are spayed or neutered by six months of age are far less likely to develop behavioral issues that are related to gender-specific hormones.

9.  Tug-of-War Can Cause Dog Aggression

There has been a lot of debate over playing tug-of-war with dogs. Some people claim the game breeds dog aggression or dominant behavior, but this is a myth. This more than likely stems from the fact dogs might growl and/or snarl when playing tug-of-war, equated with bad dog behaviors even though the two have no relation.

The truth is many dogs like playing tug-of-war and there is no proof it has any negative effects on dog behavior. Tug-of-war allows a dog to exercise its healthy, predatory nature which is very mentally and physically stimulating for the dog. Tug-of-war is also a great way to reinforce the human-canine bond. 

Over the years, many professional dog trainers have said the game decreases aggressive and dominant behaviors in dogs, because it operates as a healthy outlet for these emotions. Some experts say the human should always win the game, while others say the dog should always win. Realistically, winning tug-of-war boosts your dog's confidence, while losing might humble him. If your dog has no behavior problems, you can probably switch up the winning and losing.

Interesting fact:  Tug-of-War was practiced in ancient Egypt, Greece and China, where legend has it the Sun and Moon played tug-of-war over the light and darkness.