Surface mucus in the non-glandular region of the equine stomach

In horses, ulceration of the non-glandular region of the stomach is common and has been attributed to the lack of a protective mucus covering. This study aimed to determine whether the non-glandular region is covered by a mucus layer. A mixture of antibodies raised against human gastric mucin (MUC5AC) showed a tissue distribution in the glandular region of the equine stomach similar to that seen in humans. Dot blots of mucus from the glandular and non-glandular regions showed cross-reactivity with these antibodies. Various histological fixation and processing techniques were compared for their ability to preserve mucus in the non-glandular region. Fixing frozen sections on-slide for 20 seconds in 20 per cent formalin/1 per cent cetylpyridinium chloride was considered the best method. In conclusion, the equine stomach expresses a gene homologous to human MUC5AC. Its product is expressed as a neutral mucin, which is present in the mucus that covers both the glandular and non-glandular regions. Future comparison of mucus composition in the healthy and ulcerated stomach will improve our understanding of gastric ulceration in the horse.