Mechanical small bowel obstruction (SBO) is a frequent cause of acute vomiting in dogs, with foreign bodies being the most common cause, accounting for 80% of cases, followed by intestinal neoplasia and intussusception (1,11). Foreign bodies include materials that are not part of the normal diet, such as cloth, bones, toys, strings, and similar items (11). In humans, particulate feculent material mingled with gas bubbles in the small intestines, described as the small bowel feces sign, can be seen in 55.9% of patients with SBO, and some require surgical intervention (6,9). However, in veterinary medicine, there has only been a single reported case of small bowel fecal materials (SBFMs) in a dog with postoperative intra-abdominal adhesions (7).

This case report describes a case of SBO caused by SBFM in a dog, as well as the associated clinical signs, diagnostic imaging characteristics, and treatment. To the best of the author’s knowledge, this is the first report of SBO solely caused by SBFM in a dog.

A 12-year-old spayed female dog weighing 4.2 kg presented with a 4-day history of vomiting and anorexia. The dog had been diagnosed with diabetes mellitus 14 months prior to presentation and had been receiving medical management and strict home-made dietary control for this condition. There was low possibility of foreign body ingestion and coprophagia based on the history taking. Physical examination revealed slight abdominal discomfort and mild shivering. A complete blood cell count, blood chemistry analysis, electrolyte testing, and Vcheck serum canine pancreatic lipase test showed mild hyperglycemia (blood glucose concentration: 154 mg/dL, reference range: 70-143 mg/dL) and an elevated C-reactive protein level of 5 mg/dL (reference range: 0.1-1.0 mg/dL), with no other abnormalities detected.

Abdominal radiography revealed generally dilated small intestines filled with gas (maximal small intestinal diameter/height of the body of the 5th lumbar vertebra = 2.6) and fecal-opacity material in the small intestines rather than in the colonic location (Fig. 1A, B). Transabdominal ultrasonography (Affiniti 50G; Philips, Netherlands) revealed fluid and gas retention within the duodenal and jejunal segments and irregular shaped material with moderate acoustic shadowing throughout the distal jejunum and ileum. A mildly hyperechoic mesentery was observed peripheral to the distal jejunum and ileum (Fig. 2). The stomach was mostly filled with food-suspected echogenic materials with fluid and small amount of irregularly shaped material with moderate acoustic shadowing measuring less than 1 cm. Based on the imaging findings, jejunal-ileal obstruction caused by unknown material was initially considered, and the patient was initially hospitalized for one day to monitor the movement of the intestinal material and the patient’s overall status.

Figure 1. Ventrodorsal and right lateral abdominal radiographs at the time of first presentation (A, B) and on hospitalization day 1 (C, D). The initial radiographs show generally dilated small intestines filled with gas, with a ratio of the maximal small intestinal diameter to the height of the body of the 5th lumbar vertebra (SI/L5) of 2.6 and fecal-opacity material (arrowheads) in the small intestines, rather than in the colon (A, B). On hospitalization day 1, there is movement of the fecal material, but it still accumulates in the small intestines. Gas dilation of the small intestinal segments has also progressed (SI/L5 = 2.7).

Figure 2. Abdominal ultrasonography of the ileocolic junction at the time of first presentation (A) and on hospitalization day 1 (B). Initial ultrasonography revealed irregularly shaped material with moderate acoustic shadowing in the distal ileum to the ileocolic junction (arrowheads). A mildly hyperechoic mesentery (asterisk) is observed peripheral to the ileocolic junction. On hospitalization day 1, the mesentery surrounding the same site (arrowheads) appears more hyperechoic and widened (asterisk).

During hospitalization, the patient’s diabetes mellitus was managed with blood glucose concentration checks every three hours using a flash glucose monitoring system (FreeStyle Libre; Abbott, UK) and insulin administration (Caninsulin^®; MSD Animal Health, Germany). Intravenous fluid therapy (0.9% NaCl, 20 mL/hr), metronidazole (10 mg/kg, intravenous, BID; Metrynal Inj.; Dai Han Pharm, Korea), and famotidine (0.5 mg/kg, intravenous, BID; Gaster Inj.; Donga ST, Korea) were also administered. However, during hospitalization, the patient exhibited continuous anorexia, marked lethargy, panting, a praying position, and vomiting of undigested food. On radiographic examination the following day, movement of the fecal material was observed, but it still remained in the small intestines. Furthermore, gas dilation of the general small intestinal segment progressed (maximal small intestinal diameter/height of the body of the 5th lumbar vertebra = 2.7) compared with the previous day (Fig. 1C, D). The volume of gastric ingesta was reduced but still remained in the stomach despite the patient not eating anything. On repeat ultrasound, the mesentery surrounding the obstructed site in the jejunum and ileum became more hyperechoic and widened (Fig. 2).

Based on the patient’s progressive clinical signs and imaging findings, surgical resection was performed after receiving the owner’s consent. During surgery, soft intestinal material was manipulated in the distal jejunal and ileal segments with a hyperemic serosal wall and hyperemic edematous surrounding mesentery. A small volume of ascites was also found. Resection was performed at two sites, and the presence of SBFM was confirmed (Fig. 3). Meloxicam (initial 0.2 mg/kg followed by 0.1 mg/kg, subcutaneous, SID; Metacam^®; Boehringer Ingelheim, Mexico) was additionally prescribed. After a one-day fast, a prescription wet diet (Hill’s i/d Low Fat; Hill’s Pet Nutrition, USA) was fed, and the patient showed excellent appetite. The patient underwent hospitalization and treatment for five days postoperatively and was discharged after showing a rapid recovery. To date, no recurrence has been observed after over two years of follow-up.

Figure 3. Gross appearance of the abdominal cavity (A), jejunal segment (B) with the intestinal obstruction, and its contents (C). A small amount of ascites is visible (A). The distal jejunum with the obstruction shows a hyperemic serosal wall and hyperemic edematous mesentery (B). Small bowel fecal material without a foreign body is observed (C).

This study describes a case of SBO due to SBFM that was treated by surgical removal in a dog on diabetic management. SBO caused by SBFM is very rare in veterinary practice, and the patient was diagnosed and treated successfully.

SBFM forms due to delayed transit in the small bowel, which permits more time for fluid absorption across the bowel wall, causing the accumulation of undigested food particles (10,11). Decreased intestinal motility or gastrointestinal dysmotility can occur due to primary gastrointestinal diseases including inflammation, ulceration, infectious diseases, and a postoperative abdomen (17). It can also be caused by secondary factors including acute stress, visceral inflammation associated with pancreatitis or peritonitis, electrolyte imbalances, metabolic disorders, medication usage, diabetic gastroparesis, splanchnic hypoperfusion, hypoxemia, obesity, sepsis, and neoplasia (17). There are only a few reports of gastrointestinal dysmotility caused by diabetes mellitus in veterinary medicine (15). However, in human patients with diabetic mellitus, slower gastrointestinal transit is common as a result of diabetic gastroenteropathy, which is characterized histologically by a reduced number of interstitial cells of Cajal and enteric neurons, or dysmotility induced by hyperglycemia itself (12). Considering this, although histopathological examination was not performed in this patient, it is possible that the patient’s diabetes mellitus contributed to slowed gastrointestinal transit, leading to the formation of SBFM.

In general, radiographic findings of mechanical SBO include intestinal distention, the presence of fluid or gas causing intestinal distention, visible foreign bodies, abnormal position or appearance of the bowel, and accumulation of granular material in the small intestines (3,5,13). Ultrasound findings include gastrointestinal dilatation, abnormal motility, changes in the intestinal wall thickness, the presence of peritoneal fluid, and identification of foreign bodies (13). In this case, SBFM with significant dilation of the small intestines was observed on radiographs. This was supported by the ultrasound findings, including fluid and gas retention within the duodenal and jejunal segments, abnormal material in the distal jejunum and ileum with moderate acoustic shadowing, and a mildly hyperechoic peripheral mesentery, corroborating the diagnosis of SBO. Therefore, when SBFM is identified on radiographs in patients with gastrointestinal signs, it should be noted, and the presence or absence of SBO should be diagnosed by considering other diagnostic imaging findings.

The small bowel feces sign, which describes gas bubbles mixed with particulate matter in dilated segments of small bowel observed on computed tomographic (CT) imaging, has been widely used since its first mention in humans in 1995 and is observed in approximately 55.9% of human patients with SBO (6,9,10). In veterinary medicine, there is only one report of the small bowel feces sign in a dog with postoperative intra-abdominal adhesions and obstructive SBFM in the distal jejunum and ileum, similar to our case (7). While fecalomas are known to cause obstruction by forming mass-like structures of hardened feces (4,8), the SBFM in our case was not as solidified and did not exhibit the mass-like characteristics. Previously reported imaging characteristics were mainly focused on CT images, but in the present case, the small bowel feces sign was observed on radiographs and was similar to the previously described CT findings. In addition, a combination of radiography and ultrasonography allowed the diagnosis of SBO due to SBFM. Considering that anesthesia is required for a CT examination, diagnosing SBO due to SBFM through radiography and ultrasound would be a very useful in veterinary clinical practice. Therefore, it is important to note that the small bowel feces sign may be observed on radiographs as an indication of SBO.

The role of the small bowel feces sign in determining the treatment direction for patients with SBO is a subject of conflict and debate. Several studies have found that the small bowel feces sign serves as the primary criterion for non-severity of SBO, and its presence has been significantly linked to successful non-operative treatment of patients with SBO (2,18). The severity of intestinal obstruction is closely related to the small bowel’s ability to resorb retained fluid. When the small bowel is able to absorb fluid, it results in a mixture of air and debris, which is indicates a less severe obstruction. This suggests that the presence of the small bowel feces sign reflects a less severe obstruction due to ongoing fluid resorption by the small bowel (18). On the other hand, some studies have shown a significant association between the presence of the small bowel feces sign and bowel ischemia that can occur secondary to SBO, which requires surgical intervention (14,16). Therefore, clinical symptoms, laboratory tests, and radiological findings other than the small bowel feces sign should be considered in determining the need for surgical intervention. In this case, surgical intervention was elected due to the persistent gastrointestinal clinical symptoms that persisted for over four days before presentation and the worsening of the patient’s symptoms.

A previous multivariate prediction model for SBO in humans identified four major indicators for surgery: intraperitoneal free fluid, mesenteric edema, history of vomiting, and lack of the small bowel feces sign (18). In this patient, despite the presence of the small bowel feces sign, the presence of vomiting and mesenteric edema, and the absence of a prior history of abdominal surgery indicated the need for operative exploration. In addition, considering the radiographic finding of segmental dilation with a maximal small intestinal diameter/height of the body of the 5th lumbar vertebra > 2.4, which is used in veterinary medicine to evaluate the need for surgery (5), and the rapid postoperative recovery, the decision to proceed with surgical intervention appears to have been appropriate.

The limitation of the present case was that the exact causes or underlying mechanisms of SBFM formation were not determined due to the lack of histopathological examination and advanced imaging such as CT. Further research utilizing histopathological examination and advanced imaging is warranted in patients with SBFM to better understand the etiology and pathophysiology. However, this case remains valuable as it reports a rare case of SBFM causing SBO in a dog and describes the successful treatment approach in veterinary medicine.

This case report describes SBFM causing SBO in a dog on diabetes management and successful treatment by surgical removal. SBFM can induce mechanical intestinal obstruction, and if SBFM is observed on diagnostic imaging in patients with gastrointestinal symptoms, the need for a surgical approach should be evaluated.

The authors thank Dr. Junyeong Lee from 24 Africa Animal Medical Center for his dedication to patient care and treatment.

The authors have no conflicting interests.