Occurrence and topographical mapping of gastric Helicobacter-like organisms and their association with histological changes in apparently healthy dogs and cats.

The occurrence and topographical mapping of the gastric Helicobacter-like organisms (GHLOs) and their association with histological changes were studied in apparently healthy dogs and cats. Multiple samples were collected for histological examination from the fundus, corpus and antrum of the stomach of 10 dogs and 10 cats. Fundus and corpus were also sampled for transmission electron microscopy (three dogs, six cats), and for culture (eight dogs, six cats). In all dogs, GHLOs were detected in the fundus and corpus, and in the antrum of nine dogs, and significantly more often in the fundus and corpus (in all sample sites examined) than the antrum (P < 0.01). In cats, GHLOs were demonstrated in 6/10 individuals, and in all regions and sample sites. In dogs GHLOs were detected in all sample sites of the fundus and corpus. Lymphocytes, plasma cells and lymphocyte aggregates were found in all dogs in all regions; there were significantly more plasma cells in the antrum than in the corpus (P < 0.05). Neutrophils were found in six dogs, and eosinophils in seven dogs. In cats, lymphocyte aggregates were found only in GHLO-positive cats, which also had more lymphocytes in the fundus and corpus than GHLO-negative ones (P < 0.5). In dogs, no statistically significant association was found between the number of GHLOs and inflammatory parameters. Four dogs showed histological changes comparable to mild chronic gastritis and another six dogs to mild active chronic gastritis. Mild chronic gastritis was found in the antrum of all cats, and it occurred significantly more often in the antrum than in other regions (P < 0.01). In cats, there was a statistically significant association between GHLOs and chronic gastritis in the fundus and corpus (P < 0.05). GHLOs resembling human 'Helicobacter heilmannii' were identified in all the dogs and cats studied by electron microscopy, and Helicobacter felis in one dog in addition. Culture was successful in three dogs and one cat; 'H, heilmannii' was identified in two of the dogs, and H. felis in the third dog and the cat. GHLOs were found to be common in apparently health dogs and cats. Based on the results of this study, one sample from the fundus and corpus is enough to demonstrate GHLOs. In cats, GHLOs may cause histological changes comparable to chronic gastritis, but in dogs this association remain unclear. It is also questionable if the histological criteria for human gastritis, used in the present study, are suitable for dogs and cats.