Introduction
The cardinal clinical sign of chronic gastritis is chronic or persistent vomiting in an otherwise healthy animal. The disease is probably underrepresented as many dogs and cats will vomit infrequently and the condition is commonly neglected.
Biopsy of the gastric mucosa alone is insufficient to diagnose chronic gastritis as 26% of the healthy population of dogs can have mild gastritis based on endoscopic acquired gastric biopsies (van der Gaag 1988). Gastritis is also associated with chronic enteropathies, for example, chronic antral gastritis is a complication of chronic lymphocytic-plasmacytic enteritis which is thought to be gastrin mediated (Garcia-Sancho et al. 2005). The syndrome can be classified into two groups based on etiology, chronic non-specific gastritis also known as idiopathic and thought to be immune-mediated or auto-immune, and secondary gastritis including infectious causes including spiral bacteria like Helicobacter spp., parasites including Ollulanus tricuspis, and Physaloptera spp., reflux gastritis, drug induced, food allergic, toxins, mycosis including gastrointestinal pythiosis, and uremic gastropathy (Guilford and Strombeck 1996). Bilious vomiting syndrome should also be considered as a cause when owners complain that they observe chronic vomiting in their dog first thing in the morning but the dog has normal appetite. This is caused by gastroduodenal reflux, due to motor function of the stomach altering the rate of gastric emptying with bile salts acting as a detergent and inducing gastritis (Webb and Twedt 2003).It is well established that the presence of large numbers of Helicobacter-like organisms, similar to H. pylori, is associated with lymphoplasmacytic hyperplasia and glandular degeneration of the junction of the fundus and pylorus (Lee et al. 1992). Helicobacter heilmannii, H. felis, among other species, have been reported and are often referred to as Helicobacter-like organisms (HLO) (Simpson et al.
2000). The pathogenic role of HLO has been questioned due to reports of 41-100% and 67-100% prevalence in healthy cats and dogs respectively, with higher prevalence reported in shelter or colony housed animals, less common in younger animals, and 57-100% and 72-90% of chronic vomiting cats and dogs respectively (Simpson et al. 2000).Gastritis has been described in Alaskan racing sled dogs, which is a form of exercise- induced gastritis (Ritchey et al. 2011). Complications include gastric ulcers, and hemorrhage and signs can vary from reduced performance to acute death.
Eosinophilic gastro-enterocolitis is a condition in cats that is caused by parasitism, toxoplasmosis, food hypersensitivity, hypereosinophilic syndrome, or neoplasia and can be accompanied by peripheral eosinophilia, reported in 20% of cats with this syndrome (Tucker et al. 2014). Usually these cats are elderly, with a mean age of 9.2 years (range 1-17 years) and the most commonly affected breeds include domestic shorthair, domestic longhair, and Persian. Two percent of cases will have eosinophilic infiltrates on gastric biopsies despite the most common clinical sign (80%) being chronic vomiting.
Hypertrophic gastropathy with gastritis and gastric outflow obstruction can be caused by a number of diseases such as Zollinger-Ellison syndrome caused by a gastrinoma and acquired antral pyloric hypertrophy and gastritis of older Lhaso Apso, Shih Tzu, Maltese, and Miniature Poodles, more commonly in male dogs (Bellenger et al. 1990; Walter and Matthiesen 1993). A severe form of hypertrophic gastritis, Menetrier's disease, has been rarely described in the dog. It manifests as large gastric folds in the body of the stomach appearing cerebriform, sparing the esophagocardiac area and antrum with hypoalbuminemia and anemia, the sequelae of protein-losing gastropathy (Lecoindre et al. 2012).
Breed-specific gastropathies include atrophic gastritis of the Norwegian Lundehund, and hypertrophic gastropathy of the Drentse Patrijshund, and the Basenji. Hypergastrinemia has been documented in many of these dogs and is the most likely cause of the gastritis.
More than 60% of dogs, and 84% of cats with uremia, have clinical signs ascribed to uremic gastropathy, specifically inappetence, weight loss, vomiting, hematemesis, and diarrhea (Peters et al. 2005; McLeland et al. 2014).