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Why Getting A Slobbery Kiss From Your Dog May Be A Bad Idea

Dog mouths are teeming with Capnocytophaga bacteria, which can cause a very unfun infection.


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

A Germany shepherd dog licks the face a young blonde woman.
Many kinds of bacteria called Capnocytophaga live in the mouths of dogs and cats, and they spread to people through bites, scratches, or close contact. Image credit: A. Ivashchenko/

As every dog lover knows, you’re going to get the odd lick across the face from your furry friend. This isn’t going to cause any problems aside from an unpleasantly sticky face in the overwhelming majority of occasions, but it has the potential to cause some very irksome complications in certain cases.  

An elderly woman from the UK found out the hard way. After contracting an infection from her Italian greyhound’s saliva, she ended up in intensive care for weeks with multiple organ failure.


The story of her so-called “lick of death” was told in a BMJ Case Report back in 2016. It began when she reported having slurred speech while she was on the phone with a relative, which prompted her to call an ambulance. By the time paramedics got there, she was found slumped in her armchair losing consciousness. 

She reached the hospital, where she regained consciousness and her condition improved. She reported no other symptoms, apart from a bad headache the night before.

After four days, however, her condition slipped again and she began suffering from confusion, headaches, diarrhea, a high fever, and her kidneys began to fail. She went on to suffer from reduced liver function and respiratory failure. She was moved to intensive care when it became clear she was suffering from severe sepsis, commonly known as blood poisoning.

Blood tests showed the presence of infection from Capnocytophaga canimorsus bacteria. Although rare, this bacterium is found in the mouths of cats and dogs. However, the woman showed no bite or scratch marks, leading the doctors to believe the transmission was through a lick from her pet.


“This report highlights that infection can occur without overt scratch or bite injuries. It also reminds us that the elderly are at higher risk of infection, perhaps due to age-related immune dysfunction and increasing pet ownership," the study authors wrote.

Although it is worth noting the lady was in her seventies, her immune system was relatively well-functioning and she had no underlying conditions. She had to spend two weeks in intensive care until her infection was cleared through a treatment of antibiotics. Fortunately, she recovered, but there have been odd cases where healthy people have died from Capnocytophaga infections picked up from a dog lick.

The risk of a Capnocytophaga infection is low for most people, but some people can experience severe complications, such as people with a compromised immune system, people who drink alcohol excessively, people who don’t have a spleen, or patients who are taking drugs that are toxic to cells (such as chemotherapy). 

In worst-case scenarios, the infection can even lead to heart attacks, kidney failures, and gangrene. Very occasionally, people may need to have fingers, toes, or even limbs amputated as a result of the infection. About three in 10 people who develop a severe infection die. 


This is, however, extremely rare. Around a third of households in the UK have a dog and it’s safe to say that A&E isn’t packed full of people having their legs removed because of dog kisses. 

So, while it’s worth considering that there can be some nasty things lurking in your dog's mouth, pooch-smooches are not a death sentence. 

"The last thing you want to do is alarm people that they'll be infected if they get licked or kissed by a dog," Dr Bruce Farber, chief of infectious diseases at North Shore University Hospital, told CBS News in relation to the UK case study.

A version of this article was previously published in July 2016. 


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