Inflammatory bowel disease affects density of nitrergic nerve fibers in the mucosal layer of the canine gastrointestinal tract.

The objective of this study was to determine the effect of inflammatory bowel disease (IBD) on the density of nitrergic nerve fibers in the mucosal layer of different sections of the gastrointestinal tract of dogs. Twenty-eight German shepherd hybrid dogs of both sexes, weighing from 15 to 25 kg and aged 6 to 10 y, were studied. The dogs were divided into 4 groups with 7 animals in each group: healthy animals, as well as dogs suffering from mild, moderate, and severe IBD. Immunoreactivity to neuronal isoform of nitric oxide synthase, which is a marker of nitrergic neurons, in samples of the mucosal layer in the duodenum, jejunum, and descending colon was studied using the single immunofluorescence method and the number of nerve fibers was evaluated in each observation field. The obtained results showed that IBD causes an increase in the number of nitrergic nerve fibers in all intestinal segments studied and these changes are directly proportional to the intensity of the disease process. These observations may be useful in diagnostic evaluation of the stage of canine inflammatory bowel disease in veterinary practice. The pathological mechanisms of these observed changes and the specific reasons for them are still not completely explained, however, and further study is required.