title: An investigation into the pathology of gastritis and gastric ulceration in the horse
Creators: name: Martineau, Henny
Publisher: name: University of Glasgow
Year: 2003
Subjects: subject: Veterinary science, animal diseases.

description: The last century has seen an increase in the prevalence of gastritis and gastric ulceration in the horse with both clinical and post mortem studies presently identifying over 80% of high performance horses to be affected. Lesions are most commonly found within the squamous region of the stomach where the pathogenesis is thought to be physiological. Glandular injury is less frequent and its pathogenesis is poorly understood in the absence of non steroidal anti-inflammatory drug treatment. This study was designed to investigate the true extent and variety of gastric lesions in a mixed population of 21 adult horses at post mortem. These horses were presented to Glasgow University Veterinary School over a period of nine months for euthanasia for reasons unrelated to this study. Immediately following euthanasia, each stomach was photographed and visible lesions recorded using the MacAllister lesion classification system. Full thickness gastric samples were taken from six predesignated sites incorporating all squamous and glandular types within the stomach. A representative selection of samples from gross lesions was also obtained. The presence of any Helicobacter like organisms (HLOs) was determined by sending tissue samples directly for culture on Helicobacter medium in microaerobic conditions, and fixing them in formalin for histological evaluation. Special staining methods including Warthin-Starry, immunohistochemistry and modified Giemsa stains were used to highlight the presence of any HLOs. One of the 21 stomachs had no evidence of ulceration at all, seven had lesions in the squamous region only, two in the glandular region only and eleven had lesions in both. Gross lesions in the squamous region were classified as hyperkeratosis, punctate erosions/ulcerations, diffuse erosions/ulcerations and injury at the margo plicatus (margo injuria). Within the glandular region hyperaemia, erosions and ulcerations were identified. Histological evaluation corresponded with some of these findings and included the identification of glandular metaplasia. However, distinction between erosions and ulcerations made on macroscopic grounds particularly within the glandular region were not always found to be accurate. This was confirmed by histology. Prompted by the significant role that gastritis plays in the aetiology of peptic ulceration in humans, the type and degree of gastritis in these stomachs was also assessed. A modification of the gastritis classification system in humans was used, (the Updated Sydney System), and the cellular infiltrate and reactive changes were recorded in a systematic fashion. Given the lack of existing data regarding gastritis in the horse, and the small numbers examined in this study, no specific patterns of inflammation were observed. However it was apparent that different types of inflammatory infiltrate were present (chronic and active) and some were accompanied by reactive changes (eg. hyperkeratosis, glandular atrophy), within the surrounding mucosa. No Helicobacter like organisms were identified through culture or in formalin fixed sections. In conclusion, gastritis and gastric ulceration were observed in the majority of a mixed population of adult horses examined. Lesions within the squamous region were consistent with a physiological aetiology (eg. increased gastric acidity). The Updated Sydney System was applied to the histology of the equine stomach for the first time. The inflammatory picture found within the glandular region was varied and could still be consistent with an infectious cause to this disease but no specific aetiology was determined. Further work is required to obtain more post mortem samples to assess the true variety and extent of gastritis in adult animals and use more sensitive methods for HLO detection. The basic histological investigations in this study have highlighted the subjectivity and inaccuracy of gross lesion assessment, the wide variety of lesions present and the need for further gastric sample evaluation from a larger group of horses.