Dog Myths We All Grew Up Believing: Which Ones Are Actually True?

“A wet nose means they’re healthy.”

“Dogs only eat grass when they’re ill.”

“One dog year is seven human years.”

Dog advice has always been full of sayings passed from one generation to the next. Some contain a surprising amount of truth. Others have been repeated for so long that we have simply stopped questioning them.

So, which ones actually stand up to what we now know about dogs?

We have taken seven of the best-known dog myths and looked at the evidence behind them.

1. Dogs only eat grass when they are feeling sick

Verdict: Partly true

This is probably one of the most familiar beliefs about dogs.

A dog eats grass, therefore they must be about to be sick.

Except the two do not necessarily go together.

Research into plant-eating behaviour suggests that vomiting is not the inevitable result many people assume it is. Dogs can eat grass for a number of reasons, and plenty of otherwise healthy dogs will do it from time to time.

For some dogs, grass eating may be linked to mild gastrointestinal discomfort. For others, it may simply be something they enjoy doing.

The takeaway: Occasional grass eating is not, by itself, evidence that your dog is unwell. Persistent grass eating, repeated vomiting or other changes in behaviour or health should be discussed with your vet.

2. A warm, dry nose means your dog is ill

Verdict: False

How many of us have felt a dog’s nose to decide whether they are poorly?

A dog’s nose can change from cool and wet to warm and dry throughout a completely normal day.

Sleeping, room temperature, lying near a heat source and simply not licking the nose for a while can all affect how it feels.

A dry nose can occur alongside dehydration, fever or certain health problems, but the nose alone is not a reliable way of deciding whether a dog is unwell.

The takeaway: Look at the whole dog. Changes in appetite, energy, behaviour, drinking, toileting, vomiting or diarrhoea tell you far more than whether the nose happens to be wet.

3. A wagging tail means a happy dog

Verdict: False

This is one of the most important dog myths to understand.

Tail wagging is communication, but it does not simply translate as “I’m happy.”

Dogs may wag their tails when they are excited, uncertain, socially interested or experiencing tension.

Research has even found differences in the direction of tail wagging in response to different situations, suggesting that tail movement carries more information than we once realised.

The takeaway: Never judge a dog’s mood from the tail alone. Look at the whole body, including posture, facial expression, ears, movement, tension and what is happening around them.

4. Dogs are colour-blind

Verdict: Partly true

If by colour-blind we mean that dogs see the world entirely in black and white, this one is wrong.

Dogs can see colour.

Humans usually have three types of colour-sensitive cone cells, while dogs have two. This gives dogs a more limited colour range than ours.

Their vision is often compared with human red-green colour blindness.

So the world does not look grey to your dog. They simply do not distinguish colours in quite the same way we do.

The takeaway: Dogs see colour, just a narrower range than humans.

5. One dog year equals seven human years

Verdict: False

The seven-to-one rule is wonderfully simple.

Unfortunately, ageing is not.

Dogs do not age at a constant rate compared with humans. They mature very quickly during their first few years, and their ageing rate changes as they get older.

Size, breed, genetics and individual health also make a difference.

A one-year-old dog is clearly not comparable with a seven-year-old child. Many one-year-old dogs are already physically and sexually mature.

The takeaway: Life stage, breed and size give a much more useful picture of ageing than simply multiplying a dog’s age by seven.

6. Dogs can smell fear

Verdict: There is truth in it

This sounds like something parents tell children so they will stay calm around an unfamiliar dog.

But there is some fascinating science behind it.

Research has shown that dogs can respond differently to human body odours produced during different emotional states.

Dogs are not literally smelling an abstract emotion called fear. They are detecting chemical changes in the body that accompany it.

Those changes can influence the way a dog behaves.

The takeaway: Our bodies may communicate far more information to dogs than we realise.

7. You cannot teach an old dog new tricks

Verdict: False

Older dogs may learn differently from younger dogs, but that does not mean they stop being capable of learning.

Age can affect speed, memory and concentration, and some dogs may need a little more time to work things out.

But older dogs can still learn new behaviours, enjoy problem-solving and benefit from appropriate mental stimulation.

A senior dog may not pick something up as quickly as a two-year-old, but slower does not mean incapable.

The takeaway: Keep older dogs thinking. Appropriate training, sniffing, problem-solving and new experiences can remain valuable parts of life as dogs age.

So, were our grandparents completely wrong?

Not at all.

That is perhaps the most interesting thing about dog folklore.

Some observations made long before we had modern behavioural research were surprisingly perceptive.

Dogs really can detect changes associated with human fear. Older dogs really can continue learning. But some familiar sayings have not survived quite so well.

A wag is not necessarily a happy dog. A dry nose does not automatically mean an ill dog. Dogs do not see entirely in black and white. And multiplying their age by seven tells us surprisingly little.

That is why we are starting a new Betty & Butch series looking at the dog advice we have all heard over the years and asking one simple question:

True, false or somewhere in between?

We will be putting the questions to our team and looking at what the evidence actually says.

And we want yours.

What is the strangest piece of dog advice you have ever been given?

Tell us. It might be the next one we investigate.

Wellness Begins in the Bowl.