Dogs can tell if you're happy or sad new study suggests

Do you ever feel like your dog knows when you're happy or sad?

Well, scientists have found that dogs really can pick up on our emotions - and they seem to have a soft spot for happy faces.

New research suggests that when a dog sees someone smile, it can activate the part of its brain linked to feeling good.

Experts say that this was true even when the cheerful person was someone the dog had never met before.

Scientists at the University of Vienna in Austria wanted to take a closer look at what happens inside a dog's brain when it sees different human emotions.

They looked at 14 dogs, who sat very still inside a special machine, while being shown photographs of people's faces.

The dogs were shown faces showing a range of emotions such as happiness, anger, fear and sadness.

Experts noticed that when the dogs saw smiling faces, an area of the brain linked to reward became activated.

This is the part of the brain that responds when we enjoy something or remember something good - such as eating tasty food or getting praised.

Dr Laura Cuaya, one of the study's lead researchers, said that this brain region helps give us having motivation to do things.

"This finding suggests that happy faces, even those of strangers have a positive value for dogs," she explained.

The team also found that the dogs' brains responded differently to positive and negative emotions.

However, they did not seem to be able to tell the difference between different negative emotions in the same way.

Dr Cuaya added that the results show that a dog's brain "is quite fascinating."

"They are really good at understanding emotions in humans - a species that is completely different from them," she explained.

Dr Cuaya hoped the findings will help people to better communicate with their own beloved canine companions.

"We can reward our dogs with treats, but also reward them with happiness. So we should smile at the dogs - even at random dogs in the street."