Lymphocytic myenteric ganglionitis associated with equine herpesvirus infection: A cause of chronic intestinal pseudo‐obstruction and recurrent colic in an adult horse
Authors: Magalhães Mariana Torres, Palmers Katrien, De Cock Hilde, Ribonnet Caroline
Journal: Equine Veterinary Education
Summary
# Lymphocytic Myenteric Ganglionitis and Equine Herpesvirus: An Emerging Cause of Chronic Colic Chronic intestinal pseudo-obstruction (CIPO) is an uncommon condition in horses, but this 2024 case report documents a particularly significant presentation: a 12-year-old Quarter Horse with 1.5 years of recurrent colic and progressive weight loss caused by lymphocytic myenteric ganglionitis (MG) associated with both equine herpesvirus 1 and 5 infection. Clinical examination consistently identified small colon impaction and enlargement on repetitive transrectal palpation, whilst postmortem findings revealed the pathognomonic alternating segments of dilated and narrowed intestine characteristic of CIPO, with histopathology confirming lymphocytic infiltration and neuronal degeneration throughout the large intestine alongside PCR confirmation of viral DNA in affected tissues. The association between herpesvirus infection and enteric ganglionitis appears to involve direct viral damage to the myenteric plexus—the nerve network controlling intestinal motility—though the precise mechanisms remain unclear and warrant further investigation. For practitioners, this case highlights that recurrent, treatment-resistant colic with documented impaction alongside weight loss and poor response to medical management warrants consideration of neurological enteric pathology; whilst CIPO remains rare, heightened awareness of its presentation and potential viral aetiology may enable earlier diagnosis and allow for more targeted therapeutic approaches in future cases rather than the prolonged symptomatic management this horse experienced.
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Practical Takeaways
- •Consider viral infection (particularly EHV-1 and EHV-5) as a potential underlying cause in horses with recurrent colic and weight loss unresponsive to standard management over extended periods
- •Myenteric ganglionitis should be included in the differential diagnosis for chronic intestinal pseudo-obstruction; early recognition may lead to improved treatment approaches
- •Advanced diagnostics including PCR testing of intestinal tissues may be warranted in cases of refractory colic with consistent small colon impaction on multiple examinations
Key Findings
- •EHV-1 and EHV-5 DNA detected via PCR in intestinal tissues of a horse with myenteric ganglionitis and chronic intestinal pseudo-obstruction
- •Histopathological analysis revealed lymphocytic infiltrates and neuronal degeneration in the large intestine with alternating segments of enlarged and reduced luminal diameter throughout the entire intestinal tract
- •A 12-year-old Quarter Horse presented with 1.5 years of recurrent colic and weight loss associated with myenteric ganglionitis-induced CIPO