They are man's best friend - but you should stop letting your dog lick your face IMMEDIATELY, experts are warning.

Of course, it can be tough to stop your four-pawed pal jump up and greet you with its moist mouth when you walk through the door from a long day at work.

Your dog is there to provide companionship, comfort and a little bit of care in amongst the dreary day-to-day grind.

But, if you allow them to lick your face, you are seriously putting your health at risk - according to experts, anyway.

Our furry friends' mouths host "an enormous oral microbiome of bacteria, viruses and yeast," Dr. Neilanjan Nandi told The New York Times.

While a dog's saliva contains proteins which assist in healing and cleansing its own wounds, Dr Nandi adds: "There are some organisms unique to dogs that we were simply not meant to tolerate or combat."

For example, some bacteria in dogs' mouths are zoonotic, which means they can be passed from animals to humans - and cause disease.

A woman walking a dog

A lecturer of community practice service at Cornell University’s College of Veterinary Medicine, meanwhile, Dr. Leni K. Kaplan, added that common zoonotic bacteria include clostridium, E. coli, salmonella and campylobacter, which can cause severe gastrointestinal disease in humans.

In addition to these delights, dogs can carry hookworms and roundworms from eating faeces and licking other dogs.

As cats don't eat faeces, though, the same risks aren't attached.

But you should still be careful.

Cats mouths do harbor Pasteurella, which can lead to skin and lymph node infections, as well as Bartonella henselae, a bacterium which can also cause a severe skin and lymph node infection called cat scratch fever.