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EQUINE VETERINARY EDUCATION


Equine vet. Educ. (2020) 32 (1) 18-21 doi: 10.1111/eve.12905


Case Report


Small intestinal adenomatous polyps resulting in chronic obstruction in a 3-year-old Quarter Horse gelding J. T. Younkin†


, I. J. Kim‡, J. D. Lutter† and C. K. Ganta‡*


†Veterinary Health Center and Department of Clinical Sciences, Kansas State University; and ‡Kansas State Veterinary Diagnostic Laboratory, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, USA *Corresponding author email: ckganta@vet.k-state.edu


Keywords: horse; adenomatous polyp; colic; ultrasound; tumour


Summary A 3-year-old, Quarter Horse gelding was admitted to Kansas State University Veterinary Health Center with a primary complaint of colic. The horse had a 3-month history of recurrent colic and progressive weight loss. On physical examination, the horse was quiet, alert and responsive. The horse’s mucous membranes were pink and capillary refill time was 2 s. His rectal temperature was 37.6°C(99.6°F), heart rate was 56 beats/ min and respiration rate was 16 breaths/min. Rectal palpation revealed an approximately 5 cm dilated, firm, tubular, mass traversing from left caudal abdomen to mid abdomen. Nasogastric intubation obtained 6 L net reflux. A 5 cmdiameter small intestinal intraluminal mass was detected by abdominal ultrasound. Complete blood count, serum chemistry and peritoneal fluid analysis were performed and all results were unremarkable. The horse was humanely euthanised due to pain and financial constraints. Post-mortem examination and histopathology revealed a 15 3 5 3 5 cm polyp with multiple smaller satellite polyps that obstructed the distal duodenum. Colic was considered secondary to small intestinal obstruction and luminal distension caused by the adenomatous polyps. To the authors’ knowledge,thisisthe firstreporttoinclude ultrasound images of a small intestine adenomatous polyp that caused small intestinal obstruction and colic ina3-year-old horse.


Introduction


Small intestinal neoplasia has been previously described in domesticated species including the horse. Intestinal neoplasia in the horse is uncommon; however, it has been reported to be the cause of severe gastrointestinal disease and death. Small intestinal tumours are reported to cause obstruction, alter intestinal motility, and cause protein losing enteropathy in horses (Patterson-Kane et al. 2000; Watt et al. 2001; Gold et al. 2006; Moran Mu~


noz et al. 2008). Adenomatous polyps are benign


neoplastic lesions composed of tubular, villous or tubulovillous intestinal epithelial proliferations. Adenomatous polyps have been reported in the intestinal tract of cattle, sheep, cats, dogs, horses and humans (Patterson-Kane et al. 2000; Saulez et al. 2004; Furness et al. 2013). In humans, villous adenomas are most commonly found in the duodenum (Levine and Kaplan 1996). A definitive diagnosis of small intestinal neoplasia is usually made post-mortem or histologically. The objective of this paper is to describe the history, clinical examination findings, diagnostic ultrasound images, post-mortemand histological findings of a 3- year-old Quarter Horse gelding diagnosed with small intestinal adenomatous polyps.


© 2018 EVJ Ltd Case history


A 3-year-old, Quarter Horse gelding (363 kg) was admitted to the Kansas State University Veterinary Health Center with a primary complaint of colic. The horse had a 3-month history of recurrent colic and progressive weight loss. The horse had been housed in a 7.3 9 7.3m(24 9 24 ft) run and was routinely turned out on brome pasture. He was fed quality brome grass hay and pelleted feed and was ridden 2–3 times/week. The horse had never showed signs of colic while ridden. The horse was administered a 10 mg/kg bwt dose of fenbendazole (Panacur) 2 months prior to presentation. The horse had been showing intermittent colic signs for 3 months prior to presentation and the colic episodes responded to an unknown amount of flunixin meglumine (Banamine) administered intramuscularly by the owner.


Physical examination The gelding was quiet, alert and responsive with a body condition score 5/9 (Henneke et al. 1983). Mucous membranes were pink and capillary refill time was 2 s. The horse’s rectal temperature was 37.6°C (99.6°F), the heart rate was 56 beats/min and the respiration rate was 16 breaths/ min. Auscultation of the heart and lungs revealed no abnormalities. Abdominal auscultation revealed increased borborygmi and the horse’s abdomen did not appear grossly distended. Rectal examination revealed an approximately 5 cm diameter firm, tubular mass traversing from left caudal abdomen to mid abdomen that was associated with the small intestine. Nasogastric intubation obtained 6 L net reflux.


Clinical diagnostics All haematological and serum biochemical results were within reference ranges. Peritoneal fluid analysis revealed a normal total nucleated cell count of 1.2 9 109/L (rr <1.5–5.0 9 109/L) and total protein of 0.3 g/L (rr <0.1–0.2 g/L) (Brownlow et al. 1981). Abdominal ultrasound revealed a small intestinal luminal mass in the cranial ventral abdomen 10 cm cranial to the umbilicus and 5 cm to the right of midline as shown in Figure 1. The mass was heterogeneous in appearance with a distinct hyperechoic wall with a hypoechoic intraluminal center.


Differential diagnosis A clinical diagnosis was made of a small intestinal intraluminal mass causing secondary intestinal obstruction. The ultrasound and rectal findings supported our clinical diagnosis. Differential diagnoses included small intestinal foreign body,


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