20


EQUINE VETERINARY EDUCATION / AE / JANUARY 2020


a)


c)


b)


d)


Fig 2: Gross and microscopic image of a distal duodenal polypoid mass. a) In situ image of the exteriorised aboral portion of the luminal mass in the proximal jejunum. A clear demarcation can be visualised between the markedly distended and normal jejunum. b) Jejunal lumen showing a pedunculated dark red mass arising from the mucosa. Similar smaller polypoid masses are located oral and aboral to the large polypoid ulcerated mass. c) The mucosa is elevated into a polypoid mass with submucosa continuing into the polyp. The submucosa is expanded by oedema. d) Higher magnification (403) of the polypoid mass showing mucosal hyperplasia, submucosal oedema (arrow) with submucosal mucosal glandular hyperplasia (asterisks).


authors’ knowledge, this is the first case report to include an ultrasound image of a small intestinal adenomatous polyp in the horse. On gross and microscopic examination, the mucosa was


elevated and continuous with the normal mucosal epithelium forming multiple elevated polypoid masses. The mucosal epithelium showed occasional branching with no evidence of infiltration into the submucosa. The features identified by gross and microscopic examination were consistent with intestinal mucosal adenomatous polyps causing mechanical obstruction in the distal duodenum as previously reported (Patterson-Kane et al. 2000). In contrast to previous cases of intestinal neoplasia, no


protein losing enteropathy was identified in this case (Datt and Usenik 1975; Colbourne et al. 1996; Gold et al. 2006; Taylor et al. 2006; Moran Mu~


noz et al. 2008), suggesting that not all


intestinal polyps are associated with weight loss and protein losing enteropathy. However, the mechanical obstruction caused by growing polyps can result in colic; hence, it is important to rule out polyps as one of the differential diagnoses. In cats diagnosed with adenomatous polyps, chronic abdominal pain, vomiting, and melena have been described (MacDonald et al.1993). The history of this particular horse having chronic episodes of colic parallels the clinical signs of gastrointestinal abnormalities associated with adenomatous polyps in other species. The clinical findings were consistent with obstruction and a likely surgical lesion. Intestinal polyps have been reported in foals to cause bowel obstruction and intussusception. To the author’s knowledge, it is currently unknown whether intestinal neoplasia is congenital


© 2018 EVJ Ltd


in the horse (Colbourne et al. 1996; Gold et al. 2006). In horses, intestinal adenomatous polyps may occur spontaneously or as part of one of several large intestinal inherited syndromes (Patterson-Kane et al. 2000). In this case, it could not be determined whether or not this 3-year-old Quarter Horse gelding’s intestinal neoplasia was congenital or acquired. In summary, small intestinal tumours occur uncommonly in


horses and are typically diagnosed on post-mortem examination. However, as in


this particular case,


ultrasonography can prove to be valuable in distinguishing a small intestinal intraluminal polyp from a small intestinal intussusception. The ante-mortem clinical diagnosis of small intestinal intraluminal neoplasia was confirmed by gross and histopathological examination. The neoplasia was identified as a small intestinal adenomatous polyp. Ultrasonography is a valuable diagnostic tool to utilise in horses exhibiting progressive intermittent signs of colic, especially in young horses.


Authors’ declaration of interests No conflicts of interest have been declared.


Ethical animal research This case report passes ethical review.


Source of funding None.


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