Extensive Myenteric Ganglionitis in a Case of Equine Chronic Intestinal Pseudo-obstruction Associated with EHV-1 infection.

We describe a case of progressive myenteric ganglionitis in a 7-year-old male trotter horse with a history of recurrent colic. Clinical findings were consistent with chronic intestinal pseudo-obstruction (CIP) syndrome. At laparotomy, an impaction of the descending colon associated with a marked atrophy of the right dorsal colon was found. At post-mortem histological examination, a diffuse enteric ganglionitis, consisting in CD3+ lymphocytes and plasma cells, was observed. In all intestinal tracts the number of myenteric ganglia and of healthy ganglion cells was significantly decreased, while chromatolytic/necrotic neurons and periganglion connective tissue were increased. A slight decreased immunoreaction for NSE, and a moderate increase in S100 and GFAP immunoreaction were also recorded in the necropsy specimen of the right dorsal colon compared with corresponding biopsy sample. Immunolabeling and semi-nested PCR test for ERV/EHV-1 performed on the gut were positive supporting an aetiological relationship between EHV-1 infection and the reported equine enteric ganglionitis.