DOI: 10.1111/eve.13930_1 C A S E R E POR T
Lymphocytic myenteric ganglionitis associated with equine herpesvirus infection: A cause of chronic intestinal pseudo- obstruction and recurrent colic in an adult horse
Mariana Torres Magalhães 1,2 | Katrien Palmers 1 | Hilde De Cock 3 | Caroline Ribonnet 1,4
1 Equine Clinic De Morette , Asse , Belgium 2 Faculdade de Medicina Veterinária de Lisboa , Universidade de Lisboa , Lisboa , Portugal 3 Veterinary Pathology Services , Zoolyx , Aalst , Belgium 4 Rossdales Equine Hospital and Diagnostic Centre , Exning , United Kingdom
Correspondence: Caroline Ribonnet Email:
caroline-ribonnet@hotmail.be
SUMMARY
A 12- year- old Quarter Horse gelding presented with a 1.5- year his- tory of recurrent colic and weight loss. The horse was regularly de- wormed and vaccinated, and previous episodes had resolved with medical treatment, but no diagnostics or treatments resolved the recurrent nature of the colic episodes. Repetitive transrectal exami- nations consistently revealed small colon impaction and enlargement. Further examinations were carried out, including gastroscopy, a faecal sampling, red worm serology and rectal biopsies, and the only abnor- mal finding was mild chronic neutrophilic and eosinophilic proctitis. A low bulk diet alongside a colon- specific anti- inflammatory therapy (sulfasalazine), transfaunation, deworming and laxatives were initi- ated. The horse ' s condition deteriorated and the frequency of colic episodes increased. Systemic corticosteroid therapy and exploratory laparotomy were suggested but declined by the owner. Due to the de- teriorating and recurrent nature of the problem, it was then decided
to euthanise the horse. During postmortem examination, alternating segments of enlarged and reduced luminal diameter were observed throughout the entire intestinal tract (Figure 1). Histopathological examination showed lesions in the myenteric plexus of the large in- testine, characterised by lymphocytic ganglionitis and neuronal de- generation of the large intestine. Immunohistochemical examination indicated a T- cell infiltrate in the ganglia. Myenteric ganglionitis (MG) is a rarely described cause of chronic intestinal pseudo- obstruction (CIPO)
in horses and other species. Species- specific PCR analysis
detected EHV- 1 and EHV- 5 DNA in the large intestine tissues, sug- gesting a possible association between neurotropic viruses and the development of MG, as described in other equine studies. Treatment of CIPO remains supportive, with immunosuppressive therapy show- ing promise in some cases. Despite the poor prognosis in horses, this report emphasises the importance of early diagnosis and increased recognition of this disease to improve future diagnosis, treatment and prognosis. This is the first reported case associating MG with concomitant EHV- 1 and EHV- 5 in horses, highlighting the need for further research into the pathophysiological relationship between inflammation, neuronal degeneration and equine herpesvirus in the gastrointestinal tract.
K E YWORDS horse , chronic intestinal pseudo- obstruction , herpesvirus , myenteric ganglionitis , recurrent colic
Key points
• Lymphocytic myenteric ganglionitis should be considered in the differential diagnosis for recurrent colic.
• A clinical manifestation of myenteric ganglionitis is chronic intestinal pseudo- obstruction (CIPO) in horses and other species.
FIGURE 1 A section of small intestine with clearly different lumen sizes.
288 | © 2023 EVJ Ltd.
• Histopathology, immunohistochemical examination and PCR of full- thickness intestinal biopsies are essential to confirm the diagnosis of this condition.
aaep.org/wiley-redirect Equine Vet Educ. 2024;36:288.
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