1. Dogs are color blind
The origin: The basis for this myth is not known.
The truth: Dogs do see in color. However, they see differently than most people do and are less able to distinguish between colors. Veterinary ophthalmologists have determined that dogs see like people who have red/green color blindness. Dogs’ eyes have receptors for blue and green shades, but not for red shades. As a result, it appears that dogs cannot easily distinguish between yellow, green and red, but they can identify different shades of blue, purple and gray. Color is only one of many visual stimuli that dogs detect in their environment. Brightness, contrast, and especially motion, are extremely important to a dog’s interpretation of what it sees.
3. If a dog’s nose is warm, it means it’s sick
The origin: There is no identifiable origin for this myth. People just seem to think that a dog with a warm and/or dry nose is sick, and that a dog with a cold wet nose is well.
The truth: If a dog has a dry or warm nose, it means that he has a dry or warm nose. A dry nose or a mildly warm nose has nothing to do with the overall health of a dog.
4. If a dog is wagging its tail, it is happy
The origin: Most dogs do wag their tails when they are happy. As a result, people associate a wagging tail with a happy dog.
The truth: In many cases, a dog that is wagging its tail is happy, or at least is expressing excitement or pleasure. Tail-wagging certainly does express a strong state of emotion, much like a smile does in people. However, just like a human smile, a dog’s wagging tail does not necessarily reflect happiness or something positive. Dogs frequently wag their tails when they are agitated, irritated, tense, anxious, annoyed, frightened, angry or aggressive. Interestingly, researchers have found that dogs do not normally wag their tails when they are alone, even if they apparently are happy or are in a pleasant situation. Tail-wagging seems to be a behavior that is reserved for times when the dog is in the company of others.
6. A dog’s mouth is cleaner than a human’s mouth
The origin: Dog saliva was once believed to be antiseptic, and some people still believe it has healing properties. The basis for this belief is not known.
The truth: A dog’s mouth is not “cleaner” than a person’s mouth. Dog saliva can be toxic to some bacteria, but it carries its own population of bacteria and other infectious organisms. That population is just different from the assortment of bacteria and other “germs” in the human mouth, based largely upon differences in diet. There is a reason for the term, “dog breath.” People with weakened immune systems and young children probably should not have direct contact with dog or cat saliva.
7. One year of a dog’s life is equal to 7 years of a human’s life
The origin: The basis for this myth remains a mystery. It probably comes from simple math: an average life span for dogs is 10 to 12 years, and multiplying this by seven equals 70 to 74 years, roughly the average life span for people today.
The truth: Contrary to popular belief, there is no exact formula to gauge how much a dog develops or ages in comparison to so-called “people years.” Aging is as individual for dogs as it is for people. Taking a dog’s age and multiplying it by 7 is an overly simplistic formula and does not reflect a dog’s actual developmental status. A more accurate rough guide is as follows:
- 1-year-old-dog equals a 15-year-old human
- 2-year-old-dog equals a 24-year-old human
- 4-year-old-dog equals a 32-year-old human
- 7-year-old-dog equals a 45-year-old human
- 10-year-old-dog equals a 56-year-old human
- 15-year-old-dog equals a 76-year-old human
- 20-year-old-dog equals a 98-year-old human
Of course, there is a distinct difference in aging between small dogs and giant breed dogs. Large dogs have a significantly shorter life span than do small dogs. Their development in the early years is about the same as other breeds; however, large and giant breed dogs developmentally are much older than smaller breeds in their later years, starting at about 7 years of age.
9. Cats purr because they are happy
The origin: This myth, like many others, doesn’t have a precise origin. It probably comes from the fact that most cats do purr in the presence of their owners when they are being petted, which we interpret as a sign of happiness.
The truth: Most cats do purr when they are happy. However, that is not the only time they purr. Cats will sometimes purr when they are sick, stressed, injured, frightened or in pain. They also can purr when they are giving birth, and even as they are dying. Purring seems to be more an expression of some strong emotion – whether positive or negative – than it is an expression of any particular emotion, including happiness. Purring by a cat might be similar to humming or whistling by a human: it commonly is done out of happiness, but it may also be done as a result of stress, fright or discomfort.
10. Cats can see in the dark
The origin: This myth probably originates from people observing cats navigating at night. Cats are often active at night and do tend to get around very well in the dark.
The truth: Although cats do see better in semi-darkness than people, they cannot see in total darkness. The pupils of their eyes open much wider in dim light than those of people, letting in more light during the normal hunting hours of dawn and dusk. But again, cats cannot see in complete darkness.