Helicobacter spp are commonly found in the stomachs of both healthy and vomiting dogs and cats, but their significance is unknown. While H pylori infections in people have been linked to gastritis, peptic ulcers, and a higher rate of gastric neoplasia, similar direct casual relationships between Helicobacter infections and GI disease have not been established in dogs and cats.
Etiology and Pathophysiology
Helicobacter organisms are spiral or curved, gram-negative, motile, flagellated organisms. H pylori is the most commonly reported species in human GI infections, but larger Helicobacter-like organisms (such as H felis, H heilmannii, and H bizzozeronii) are more common in dogs and cats. At least 38 different Helicobacter species have been identified in animals, and infected animals can harbor multiple species.
Helicobacter organisms have been identified most commonly in the gastric tissue of dogs and cats, especially in the fundus and cardia of the stomach, but they are also found in the intestinal tract. Colonization of gastric mucosa appears to be most prevalent in the surface mucus layer, as well as within the gastric glands and parietal cells. There have been sporadic reports of Helicobacter organisms identified in the hepatic tissue of a dog with multifocal necrotizing hepatitis, as well as in normal cats and in cats with cholangiohepatitis.
Clinical Findings and Diagnosis
Gastritis, vomiting, and diarrhea have been associated with Helicobacter infection, although a direct causal relationship has not been identified. Peptic ulceration is rarely associated with Helicobacter infections in dogs and cats.
Diagnosis involves upper GI endoscopy or exploratory laparotomy. Surface mucus from a large area of the stomach can be obtained by taking brush samples via endoscopy. If organisms are present, they are readily identified under 100× oil-immersion magnification. Because brush cytology samples a large area of the stomach, the sensitivity of this test is high.
Gastric biopsies should be obtained from multiple areas in the stomach, because organism distribution can be patchy. Routine H&E staining is usually sufficient to identify organisms, although special silver stains may be required if the organisms have a glandular location. Mucosal inflammation, glandular degeneration, and lymphoid follicle hyperplasia accompany some infections. Cytology and histopathology is not sufficient to identify specific species. A commercially available rapid urease test to detect production of bacterial urease in gastric biopsies can identify the presence of Helicobacter organisms. However, because cytology and histopathology are highly sensitive and specific for detection of Helicobacter infections, urease testing adds little to diagnosis.
Noninvasive tests for Helicobacter infection available in the research setting include urea breath testing, fecal antigen detection, and serology.
The lack of knowledge regarding the pathogenicity of Helicobacter infections in dogs and cats makes treatment decisions difficult. H pylori infections in people are treated with double or triple antimicrobial agent therapy plus an acid secretory inhibitor (eg, clarithromycin, amoxicillin, bismuth, and ranitidine) for 2 wk, and similar therapeutic approaches have been used in veterinary medicine.
However, Helicobacter infections in dogs and cats have been difficult to eradicate, and specific treatment recommendations cannot be made. Some clinical studies cite improvement of chronic gastritis and vomiting after treatment of Helicobacter-infected dogs and cats, suggesting that treatment of infections in dogs and cats showing clinical signs should be considered.
Transmission of Helicobacter infections between groups of dogs and cats is unclear, and reservoir hosts have not been defined. Because of the increased rate of morbidity and mortality associated with H pylori infections in people, concerns about zoonotic transmission have been raised. H pylori infection has been reported in one feline research colony; it has not been identified in dogs. While some studies suggest a higher risk of Helicobacter infection in people who are in contact with dogs and cats, other research refutes this. Therefore, the zoonotic transmission of Helicobacter is considered possible but the risk is likely low. Regardless, proper hygiene practices are encouraged, and identification of infections in dogs and cats with chronic gastritis and vomiting is likely prudent.
Last full review/revision March 2012 by Shauna L. Blois