Idiopathic Intestinal Smooth Muscle Hyperplasia in a French Bulldog: Clinical, Imaging, Capsule Endoscopy, and Histopathological Findings.

A 3-year-old intact female French Bulldog presented with chronic diarrhea, intermittent vomiting, hyporexia, and weight loss over seven weeks. The blood test results were unremarkable, except for mild hypocholesterolemia. Abdominal ultrasonography revealed intestinal wall thickening, particularly in the muscular layer, with focal loss of wall layering in the distal ileum near the ileocecal junction. Capsule endoscopy revealed mild-to-moderate mucosal irregularities and changes in the ileum, with a reduced luminal diameter caused by irregularly protruding walls, leading to the partial obstruction of the distal ileum. To remove the obstructed segment, surgical resection and anastomosis were performed from the distal ileum to the ileocecal junction, including the ileocolic valve region. Histopathological examination confirmed intestinal smooth muscle hyperplasia with mild infiltration of macrophages, neutrophils, and lymphocytes. As the underlying cause could not be identified, the condition was classified as an idiopathic condition. Postoperatively, long-term management of the clinical symptoms was implemented, including antibiotics, anti-inflammatory medications, and dietary modifications (the elimination of table foods). Over a one-year follow-up period, ultrasonography revealed mild recurrent inflammation and muscular hyperplasia; however, the clinical signs resolved, except for occasional episodes of diarrhea.