Lymphocytic myenteric ganglionitis associated with equine herpesvirus infection: A cause of chronic intestinal pseudo‐obstruction and recurrent colic in an adult horse

Abstract

SummaryThis report describes a rare case of chronic intestinal pseudo‐obstruction (CIPO) in a 12‐year‐old Quarter Horse gelding, caused by lymphocytic myenteric ganglionitis (MG) associated with equine herpesvirus 1 (EHV‐1) and equine herpesvirus 5 (EHV‐5) infection. The horse presented with recurrent colic and weight loss over 1.5 years. Repetitive transrectal examinations consistently revealed small colon impaction and enlargement. During postmortem examination alternating segments of enlarged and reduced luminal diameter were observed throughout the entire intestinal tract. MG with lymphocytic infiltrates and neuronal degeneration of the large intestine were found on histopathological analysis. Additionally, polymerase chain reaction (PCR) analysis confirmed the presence of EHV‐1 and EHV‐5 DNA in affected intestinal tissues. Further research is needed to understand the pathophysiology of MG and its association with herpesviruses. Early recognition and diagnosis of MG‐associated CIPO may improve treatment approaches and outcomes for future cases.

The subtle link between myenteric ganglionitis and inflammatory bowel disease

“…Thus, as anticipated by the authors of the last case report (Magalhães et al, 2024), we are facing the eternal question of what came first, intestinal inflammation or enteric neuritis. Possibly there is no definitive answer as in single cases different mechanisms may lead to the same result.…”

“…The first case of CIPO described in a horse dates back to the 90s when myenteric ganglionitis (MG) of unknown origin was diagnosed in a 4-year-old mare. Subsequently, a growing number of cases have been reported, including the one described by Magalhães et al (2024) in this issue. As anticipated by the authors of this case report, we are facing the eternal question of what came first, intestinal inflammation or enteric neuritis.…”

“…Since then, an increasing number of cases have been reported (Barros et al, 2022;Blake et al, 2012;Chénier et al, 2011;Ortolani et al, 2021;Pavone et al, 2013), including the one described in this issue by Magalhães et al (2024). Neurotropic viruses, such as equine herpesvirus, were suspected in most cases and confirmed in some of them (Barros et al, 2022;Magalhães et al, 2024;Pavone et al, 2013). Latent infection of EHV-1, indeed, has been demonstrated not only in the most common locations such as trigeminal ganglion and retropharyngeal lymph nodes, but also in abdominal neuronal and lymphoid tissues (Giessler et al, 2020).…”

“…The first case of CIPO described in a horse dates back to the 90s when myenteric ganglionitis (MG) of unknown origin was diagnosed in a 4-year-old mare (Burns et al, 1990). Since then, an increasing number of cases have been reported (Barros et al, 2022;Blake et al, 2012;Chénier et al, 2011;Ortolani et al, 2021;Pavone et al, 2013), including the one described in this issue by Magalhães et al (2024). Neurotropic viruses, such as equine herpesvirus, were suspected in most cases and confirmed in some of them (Barros et al, 2022;Magalhães et al, 2024;Pavone et al, 2013).…”

“…Latent infection of EHV-1, indeed, has been demonstrated not only in the most common locations such as trigeminal ganglion and retropharyngeal lymph nodes, but also in abdominal neuronal and lymphoid tissues (Giessler et al, 2020). However, healthy subjects rarely harbour detectable viral DNA in the myenteric plexuses, thus the presence of herpesvirus associated with MG might suggest that the virus could be related with the disease (De Giorgio et al, 2002;Magalhães et al, 2024).…”