Helicobacter species are a fascinating group of bacteria. They live in the stomach of humans and many animals, an environment that was previously thought to be completely inhospitable to bacteria. We now know that Helicobacter bacteria are beautifully adapted for survival in the stomach and are very common. In people, Helicobacter pylori is an important cause of gastritis (inflammation of the stomach), stomach ulcers and stomach cancer.

Studies looking at bacteria in the stomachs of dogs and cats have found that Helicobacter species are extremely common, with some studies finding one or more species of Helicobacter in every dog or cat that was tested. Since Helicobacter is an important problem in people, does that mean that we need to be worried about pets as a source of infection? Probably not.  Here’s why:

It could be a problem because:

  • A few studies have found the same Helicobacter species in infected people and their pets.

It’s probably not a problem because:

  • Studies looking at risk factors for Helicobacter infection in people have not identified pet ownership as a risk factor.
  • A study comparing one Helicobacter species that has been mentioned as a possible zoonotic concern, H. heilmannii, reported that H. heilmannii strains from people were generally different than those from animals.
  • While other Helicobacter species are common in dogs and cats, H. pylori (the main cause of problems in people) is rare in pets.
  • While finding the same Helicobacter species in a person and his or her pet raises concern, studies have yet to demonstrate whether such findings are due to animal-to-human transmission, human-to-animal transmission, or infection of both person and pet from the same source.

Overall, the risks of pet-associated Helicobacter infection are probably very, very low. If there is any involvement of pets in this disease in people, it’s probably sporadic at most. Avoiding contact with stool from pets and paying good attention to handwashing should decrease the risk even further.

One question that is currently unanswered is whether the mouth of a dog or cat can be a source of Helicobacter infection, because the bacterium can be found in saliva. We really don’t know whether this is a risk – it’s probably minimal at most, but avoiding contact with pet saliva (e.g. no sloppy wet dog kisses!) is a good idea anyway.