Helicobacter is a gastric spiral bacterium that has been linked to peptic ulcer disease in humans. It has also been declared a carcinogen (cancer causing agent) in humans due to its association with stomach cancers such as adenocarcinoma and lymphoma. While much is known about the organism and its clinical consequences in people, comparatively little is known about infection in dogs and cats, and it is still unclear as to whether any diseases can be attributed to these bacteria.
In the late 1800s, gastric spiral organisms were first described in humans and in animals. The discoveries demonstrated that it was possible that the highly acidic stomach, which had until that point been considered sterile, was capable of harboring a population of bacteria.
About 100 years later, interest in gastric spiral organisms was re-ignited when an association between these organisms and gastric ulcers was discovered in humans. Soon afterward, similar bacteria were isolated from the stomachs of ferrets, nonhuman primates, dogs, cats, pigs and cheetahs.
Gastric helicobacter organisms are highly prevalent in dogs. They have been identified in 61 to 82 percent of dogs that are brought to a veterinarian for vomiting; in 67 to 86 percent of clinically normal, healthy pet dogs; and approaching 100 percent of laboratory beagles and shelter dogs. Several different species of Helicobacter have been isolated from the dog, and simultaneous infection with more than one species seems to be common.
Exactly how the organism is transmitted is not clear. In people, fecal-oral spread has been hypothesized because the organism can be cultured from feces. Oral-oral spread is suggested because the organism can be found in the saliva of infected people. Recently the organism was isolated in surface water in the United States and Sweden. Similar studies have not been performed for species of the organism that can infect dogs, thus, some or perhaps all of the modes suggested for humans are possible for dogs. In dogs, transmission of the organism from a mother to her puppies
has been reported.
There is some concern about the risk of transmission of Helicobacter-like organisms from dogs and cats to humans, as some species of Helicobacter that infect humans have been found in cats and dogs. The risk seems relatively slight, however.
The role of Helicobacter in causing gastric disease in dogs is hotly debated. The majority of infected dogs do not show obvious clinical signs of gastric disease. This is in stark contrast to humans, for whom strong evidence links the organism to chronic gastritis, ulcer disease and stomach cancers. The organism has been implicated in causing gastric ulcers in ferrets and pigs, and in causing severe gastritis (stomach inflammation) in cheetahs.