In humans, Helicobacter pylori is a common cause of gastritis and peptic ulcers and increases the risk for gastric cancer. Although Helicobacter is commonly found in the stomachs of dogs and cats, its significance is unclear. In this study, 20 dogs with vomiting of at least 2-weeks duration and gastric Helicobacter infection were randomized into 2 groups to receive twice daily treatment for two weeks with amoxicillin (15 mg/kg), metronidazole (10 mg/kg), and Pepto Bismol, with or without famotidine (0.5 mg/kg). Owners maintained a daily record of clinical signs, and biopsy samples were collected during endoscopy at 4 weeks and 6 months after completing treatment. Frequency of vomiting was compared with historical rates, and percentage reduction was calculated. The status of 8 dogs changed from negative at 4 weeks to positive at 6 months (no positive dogs at 4 weeks became negative at 6 months). Eradication of bacteria occurred in 4 of 11 dogs (36%) treated with famotidine and 4 of 9 (44%) treated without famotidine (P = 0.99). However, neither treatment resulted in negative Helicobacter status at 6 months and acid suppression did not increase efficacy of treatment. Vomiting frequency decreased in positive dogs (71.2%) and negative dogs (94.6%), but Helicobacter-negative dogs had greater reduction in vomiting frequency (P = 0.0534). Although both treatments dramatically reduced vomiting frequency, improvement in positive dogs at 6 months suggests that Helicobacter infection was not a cause of vomiting or that development of clinical signs of reinfection may require more than 6 months.

COMMENTARY: The exact role of Helicobacter species as a cause of disease in dogs and cats remains to be elucidated. Some clinicians remain convinced that the organism causes signs such as vomiting while others await definitive proof. This paper unfortunately sheds little light on the topic. Both treatment groups had a reduction in vomiting, but because of lack of a control group it is possible that vomiting cessation was independent of treatment. Dogs that became reinfected showed a reduced frequency of vomiting, so proof that Helicobacter is anything more than a commensal in dogs is as elusive as ever.

Treatment of Helicobacter spp. in dogs with chronic vomiting: Results 6 months after treatment. Leib MS, Duncan RB. ACVIM PROCEEDINGS, Abstract 140, 2003, p 140.