Dogs get jealous and 19 other facts you probably never knew about man's best friend

1) Dogs don’t feel guilt

Scientists believe dogs can experience ­jealousy when their owners give attention to other dogs. But if they eat every biscuit in the house, they may look ashamed but don’t expect them to feel guilty as they don’t experience these emotions.

Researchers found those puppy dog eyes are not a sign of guilt. In fact they are just the way we interpret a dog’s reaction to being scolded.

Alexandra Horowitz, from Barnard College in New York found all dogs looked ‘guilty’ after being told off for eating a forbidden treat like a biscuit - and those who were wrongly accused often looked more ‘guilty’ than those who really deserved to be in the dog house.

2) Dog urine can corrode metal

Apparently allowing your dog to wee on a lamp-post could be more dangerous than you think - because the acids in the urine can corrode the metal.

In April 2003 Derbyshire County Council spent £75,000 carrying out a six month survey of one million lamp-posts amid fears that dog wee was causing the bases to crumple. In the same year, urinating dogs were blamed for a spate of lamp-posts collapsing in Croatia.

3) Dogs can see in colour

It is a common myth that dogs can only see in black and white but they can actually see colours - just not as vividly as humans.

They only have two cones in their eyes to detect colours, whereas humans have three. That means dogs see colours on a blue and yellow scale but cannot distinguish between red and green. On the other hand, they have better night vision than humans.

4) No compass needed

Dogs can see UV light, and don’t need a compass because they can sense the earth’s magnetic fields. It’s believed they can hear some of the ultrasound waves that bats use to navigate in the dark.

5) Their sense of smell is REALLY powerful

We know dogs have a powerful sense of smell and while we can just about smell a spoonful of sugar in a cup of tea, our canine friends are capable of smelling that same spoonful in two Olympic swimming pools’ worth of water

6) In fact, they can smell disease

If your canine chum is acting strange there might be nothing wrong with them - the problem could be with you.

Research at the Schillerhohe Hospital in Germany found dogs have an incredible ability to recognise the smell of a range of organic compounds that show the human body isn’t working as it should.

7) Dogs can be pretty smart

You might sometimes think your dog is as daft as a brush, but the truth is that they can actually be as smart as a two year-old child, according to research presented to the American Psychological Association.

Dogs can understand up to 250 words and gestures and even perform simple mathematical calculations.

Perhaps unsurprisingly, border collies are the cleverest canines, with some able to understand up to 200 words. The other breeds in the top five are poodles, German shepherds, golden retrievers and dobermans.

8) A wagging tail doesn’t always mean they are happy

Tail wagging has its own language. Apparently dogs wag their tail to the right when they’re happy and to the left when they are frightened. Wagging low means they are insecure and rapid movements accompanied by tense muscles or dilated pupils can signal agression.

9) They really are hot dogs

Next time you see your pet pooch panting on a sunny day take pity on them. Not only are they wearing a huge fur coat, they also have to contend with a higher body temperature than you.

10) Dogs have their own ‘fingerprint’

A dog’s paw print may look pretty generic but their nose print is actually as unique as a human fingerprint. Their combination of ridges and creases is so distinct it can actually be used to identify them.