dog myths - terrier

12 common dog myths

Separating fact from fiction can help you to get to know your dog, strengthen your bond and keep them healthy.

1. Dogs can only see in black and white

False – although they cannot see the world in full technicolour like we can, dogs can see some colours. Their eyes detect fewer colours than ours, so their perception is similar to humans with colour blindness.

They can tell the difference between blue and yellow, but see green and red as shades of grey.

2. My dog knows when they've done something wrong as they have a guilty look on their face

False – have you ever come home to find your pet has chewed up your child’s favourite cuddly toy, or has made a mess on the carpet? The look on their face is not guilt, but you could be forgiven for thinking it is.

Owners often mistakenly believe their dog knows they have done wrong, but what you’re actually seeing is appeasement behaviour. Dogs that look guilty are simply responding to an owner’s disappointment, upset or anger. It's their way of diffusing tension, in response to feeling worried about the changes in your behaviour.

It's important to not tell your dog off if you get home to any mess they have made while you're out. They will not understand why you're upset. But they'll quickly learn that your return home may start to predict something unpleasant for them. This can trigger appeasement behaviour on your arrival. It may also lead to an increase in the behaviours you do not want your dog to do (such as chewing or toileting), as they worry about what might happen when you return home.

dog myths - sad face

3. When my dog eats grass it means they are sick

False – eating grass is a common bugbear of dog owners. It's also a common belief that dogs eat grass to make themselves sick (usually to get rid of something nasty they’ve swallowed). Others think grass eating is a sign of a lack of some nutrients, but studies have shown this is not the case.

In fact, dogs eating grass is much more likely to be because it tastes nice, particularly in the spring and summer months when it’s green and fresh. Just make sure the grass has not been sprayed with harmful chemicals (such as pesticides), and your dog is protected from lungworm to keep them safe.

More about why your dog eats grass

dog myths - grass

4. Dogs age seven years for every human year

False – since dogs come in all shapes and sizes, working out their age in human years is not quite as simple as multiplying it by seven. Instead of thinking in human terms, it's best to learn about the different stages of life your dog will go through. This will help to make sure you're providing everything they need, from the puppy stage through to their senior years.

Different breeds take different lengths of time to reach maturity, and lifespans vary based on size and genetics, too.

5. I cannot teach my old dog new tricks

False – a dog's brain soaks up new information like a sponge and they learn very quickly. While it may take a little longer, you can certainly train an adult dog.

Dogs learn best with motivation. Grab some tasty, high value treats (like chicken or hot dog), and get ready to praise good work. The best way to go about teaching an adult dog new tricks is to make training sessions fun, keep them positive and do them little and often.


If you've noticed that your senior dog is forgetting their training, it may be a sign of cognitive dysfunction. Speak to your vet for more advice.

Dog myths - older dog

6. A female dog feels ‘empty’ if they do not have a litter

False – this is an old wives’ tale. It's also a myth that female dogs need to have one litter before spaying. Dogs are unable to feel broody, and allowing them to have one litter before getting them neutered has no proven health or behaviour benefit for them.

There is not enough evidence to say when is the best time to neuter your dog, and it can vary based on their breed, size and sex. In female dogs, it's important that they are spayed at the right time. For example, many vets will try to avoid spaying a dog while she's in season or if she’s showing signs of false pregnancy in the weeks after a season.

Neutering your female dog can prevent some illnesses such as womb infections (called pyometra), which can sadly be fatal. It can also prevent false pregnancies, which can cause behavioural problems.

7. It's OK to leave my dog in a car with the windows down on a hot day

False – it’s never OK to leave your dog alone in a hot car, even with the windows down. Cars heat up extremely quickly in warm weather, and heatstroke can be fatal to pets in a matter of minutes.

Dogs cannot sweat like we can and it’s much more difficult for them to regulate their body temperature and keep themselves cool. Dogs die in hot cars every year, so do not run the risk.

8. I have a young family so a rescue dog will not be suitable for me

False – some rescue dogs may have some behavioural challenges and sensitivities, and will not be suitable to live with young children. But many rescue dogs will have successfully lived with them in the past.

Actually, the most common reason for dogs needing our help to find them a new home is that their previous owner no longer had the time to care for a pet.

Getting an older dog, rather than a puppy, also has lots of benefits. Adult dogs’ personalities are already formed, so when you meet one at a rescue centre you can make sure they’re the right pet for you.

dog myths - dog training

9. A little bit of chocolate is fine for dogs

False – chocolate is very dangerous for dogs, and you should not give it to your dog. How dangerous depends on the type of chocolate and the size of the dog. But it can cause vomiting, diarrhoea, seizures, heart problems and can even be fatal.

Chocolate contains a chemical called theobromine, which is toxic to dogs. The amount of theobromine in chocolate depends on the type and quality of it – white chocolate only has a little, but dark chocolate contains a lot.

Small amounts of milk chocolate will probably not have dire consequences for a big dog, but it's best not to run the risk. If your dog has eaten a lot of chocolate, particularly if it’s dark, call your vet.

More about chocolate and dogs

10. I need to show my dog who’s boss by being the pack leader

False – dominance based training methods were influenced by studies of captive wolves in the 1970s. This popularised the theory that 'alpha' wolves become the leader of the pack by being aggressive towards other wolves.

As dogs are descended from wolves, people started to apply this theory to dog training. But science has moved on and this theory has now been debunked by scientists. In fact, so much more is known about wild wolves now. Wolf packs usually comprise of two parents and their offspring. Older generations may stay on with the pack, or leave to make their own. This is very different to the social structure of dogs who, although are very social, do not form packs in the same way as wolves do.

Like a human parent teaches their child right from wrong, a dog owner is responsible for helping their pet adapt to the life they share with us. It's important to help them and those they interact with feel safe. But you do not need to pull rank – your dog is not competing with you for status.

Instead, you can learn how to get the best out of your dog when you want to train something new. Or you can try a training class or dog sport, that uses reward based training techniques.

11. I can catch a cold from my dog

False (mostly!) – there are very few cold and flu viruses that affect both people and dogs. You're more likely to have caught your cold from another person, even if your dog has been coughing at the same time. Remember there are also lots of other causes of coughing, so if your dog is coughing a lot it's important to get them checked by your vet.

There are some diseases that pass easily between pets and people. Dogs can carry some bugs that cause food poisoning (salmonella, campylobacter, giardia and others) without showing any illness themselves. You can easily avoid these by washing your hands after handling dogs and after picking up poo.

Certain groups of people are more at risk, including those suffering from diseases that reduce immunity (such as Aids), or those who are either on chemotherapy or drugs following transplantation surgery. If in doubt, make sure to wash your hands or wear gloves when handling animals.

12. I can give my dog ibuprofen if they're unwell

False – human drugs are approved for use in humans, not dogs. Many human painkillers are poisonous to pets, and ibuprofen can give your dog stomach ulcers, kidney and liver failure, and can be fatal.

Never give your dog any drug unless told to do so by your vet. If your pet is ill, or is showing strange behaviours like sensitivity to light or sound, contact your vet as soon as you can.

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• 29 April 2024

Next review

• 29 April 2027

Claire crouching next to her white staffie dog
Approved by
Claire Stallard

Animal Behaviourist ABTC-CAB

Approved by
Anna Ewers Clark

Veterinary Surgeon MRCVS