This is a condition characterized by gross thickening of the gastric mucosa occurring as a diffuse or focal form involving the fundus, body or pylorus of the stomach (). It appears to be similar to a condition seen in man termed ‘Menetrier’s Disease’. The condition has been described in the cat () as well as the dog (). The focal form often involves the antrum and pylorus causing outflow obstruction or may appear like a polyp. In the diffuse form the majority of the mucosa is involved with macroscopic thickening of the mucosa and large rugal folds (3 and Plate 1). This is due histologically to glandular hyperplasia and cystic dilation of mucus glands with cellular infiltration of plasma cells and lymphocytes. Metaplastic changes lead to a loss of differentiation between the parietal and chief cells. Occasionally there is ulceration and hypertrophy of the muscle layer as well as the mucosa.
The aetiology is not known but may include autoimmune disease, genetic predisposition in Boxers and Basenjis, hormonal influence especially through excessive levels of acetylchoiine, gastrin or histamine which have a trophic effect on the mucosa (). It may also occur where there is renal disease with failure to metabolize gastrin leading to hyperacidity and gastric mucosal hypertrophy. Parasitic conditions may also be implicated, and one case in a Siamese cat reported the presence of Ullalonus tricuspis in the stomach (). Pyloric stenosis may coexist with hypertrophy gastritis and is especially seen in small breeds, nervous dogs, behaviour-associated cases and with neuroendocrine disease ().
Chronic vomiting usually occurring over several months is a feature in diffuse cases and the vomitus varies considerably from large volumes of fluid at low pH, to haematemesis where ulceration is present. If there is outflow obstruction vomiting may be described as projectile, associated with feeding and usually containing food. Anorexia, abdominal pain, diarrhoea and weight loss do occur ().
In the diffuse form, barium studies may reveal prominent rugal patterns while in the focal form these changes may be confined to the antrum and pylorus. Delayed gastric emptying is a feature when the focal pyloric form is present, together with narrowing of the antrum. Endoscopy is more helpful and reveals enlarged rugae, while biopsy confirms the diagnosis.
Hypertrophic gastritis: Treatment
Treatment must be supportive as there is no cure and thus the prognosis must be guarded. Renal and liver disease and gastrin-producing tumours should be considered. Surgical intervention is required when the focal form causes pyloric stenosis by carrying out pyloric resection () or pyloroplasty (). In the diffuse form frequent small meals using hypoallergen diets together with cimetidine (Tagamet; SmithKline Beecham) 5 to 10mg/kg every 8h or ranetidine (Zantac; Glaxo Laboratories) 0.5mg/kg every 12 h will effect control in many cases.
Selections from the book: “Digestive Disease in the Dog and Cat” (1991)