Helicobacter gastritis in dogs and cats (Proceedings)
Helicobacter pylori infection is the most common cause of chronic gastritis and peptic ulceration in humans. It is also associated with an increased risk of gastric lymphoma and adenocarcinoma. Spiral bacteria were described in 1896 in humans and several animal species. They were "rediscovered" in 1983 when they were reported to cause of peptic ulceration in humans. Helicobacter pylori is a microaerophilic curved spiral gram negative organism with 4 flagella. The bacterium lives in gastric mucus, can attach to epithelial cells, and may penetrate intercellular junctions. High bacterial urease concentration cleaves urea to produce ammonia, which helps to neutralize the acid environment surrounding the bacterium. The immune system does not result in removal of the organisms; without treatment infection is life-long. Some studies have shown as many as 90% of people are infected with H. pylori. Luckily, most infections are not associated with clinical signs. Diagnosis can be made with serology, cytology of gastric mucus, culture of biopsies, histopathology of biopsies with H&E or silver stains, C-13 or C-14 labeled urea breath tests, or rapid urease tests. Many treatments have been studied, but the gold standard to which they are all compared to is omeprazole, ampicillin or tetracycline, metronidazole, and bismuth for 2 weeks.
Many species of spiral bacteria have been identified in dogs and cats: H. felis, H. pylori, and H Heilmannii (formerly called Gastrospirillum hominis), H. Salomonis, and H. bizzozeronii are the most common. Experimentally, infection has been established in both dogs and cats and lymphoid follicular gastritis developed. However, in these experimental studies, clinical signs were absent or very mild. Several surveys of laboratory, shelter, and pet populations (with and without GI signs) have shown a very high prevalence rate in dogs and cats, nearing 100% in some studies. Peptic ulceration is very rare in dogs and cats, demonstrating the pathophysiologic difference between H. pylori and the spiral bacteria commonly found in dogs and cats. Little is known about the effects of treatment of dogs and cats with chronic vomiting and Helicobacter spp. infection. At the present time there are many unanswered questions regarding Helicobacter in dogs and cats. Some questions include: 1) What is the relationship between Helicobacter and dogs and cats with chronic gastritis and vomiting? 2) What is the optimal treatment to eradicate the organism? 3) After treatment, is reinfection or recrudescence a common occurrence in dogs and cats? 4) What factors can help predict if a dog or cat with chronic gastritis and Helicobacter would benefit from treatment for Helicobacter? 5) Does Helicobacter have a role in other diseases such as gastric cancer and inflammatory bowel disease?
Because of the potential pathophysiologic relationship between Helicobacter spp. in dogs and cats and chronic gastritis and vomiting, the author has treated clinical cases for Helicobacter. In some cases, treatment has resulted in resolution or improvement in clinical signs. Until additional studies about Helicobacter in dogs and cats are available, it seems prudent to at least determine if spiral bacteria are present in dogs and cats with chronic vomiting, during gastroscopic examination or exploratory celiotomy. Spiral bacteria can be identified in gastric biopsy or brush cytology specimens, or indirectly identified by rapid urease testing of gastric mucosal samples. Obtaining results from histologic evaluation of biopsy samples requires 24-72 hours. Results of rapid urease tests and gastric brush cytology are available much sooner.