Introduction

Mesenteric or intestinal volvulus is defined as an intestinal rotation at the root of the mesentery, causing occlusion of the cranial mesenteric artery and vein.¹ The clinical signs associated with a mesenteric volvulus occur or develop secondary to the bowel twisting on its mesenteric axis, which results in a strangulating mechanical obstruction and ischemia of the small intestines.¹ This typically leads to a peracute to acute onset of clinical signs such as severe abdominal pain, abdominal distension, hemorrhagic diarrhea, and signs of severe shock that rapidly progress to death if emergency surgery is not performed.²

In this report, an unusual presentation of mesenteric volvulus in two dogs was documented. These dogs presented without the acute or peracute severe clinical signs mentioned above and also had a concurrent foreign body obstruction. The dogs were both less than 1 yr of age, and, ultimately, both had a favorable surgical outcome.

Case Report

Case 1

A 40.5 kg 9 mo old female intact English mastiff presented to The Ohio State University’s emergency service for a 7-day history of anorexia, lethargy, and vomiting. Two days prior to presentation, the dog was evaluated by the referring veterinarian for anorexia and vomiting (physical examination findings unknown). A parvovirus antigen test was negative, and on a fecal flotation test, no oocytes were seen. Metronidazole^a and maropitant^b (doses and duration unknown) were prescribed; however, no improvement was noted. The following evening, the referring veterinarian hospitalized the dog, and enrofloxacin^c and ampicillin/sulbactam^d were started the morning after. Abdominal radiographs and a barium study were performed, which showed multiple dilated loops of small intestine with stacking and hairpin turns. The barium study did not outline a foreign body or foreign material, although contrast did not extend past the antrum of the stomach (Figure 1A). Referral was recommended with the initial suspicion of a foreign body obstruction. After radiographs were reviewed by a board-certified radiologist, the differential diagnosis of mesenteric volvulus was added.

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On presentation, dog 1 was quiet but responsive, estimated to be 7% dehydrated, and had a temperature of 39.8°C (103.7°F) and a heart rate of 120 beats per min. The dog was thin (body condition score 1.5/5), had abdominal distension with mild discomfort on palpation, and had a palpable mass in the cranioventral abdomen.

Initial blood work included point-of-care venous blood gas and electrolytes, packed cell volume and total protein, complete blood count (CBC), and a serum biochemistry panel. Electrolyte abnormalities included hyponatremia (141.6 mmol/L, reference range 143–150 mmol/L) and hypochloremia (109.8 mmol/L, reference range 111–119 mmol/L). Lactate was in the reference range (1.2 mmol/L, reference range <2 mmol/L), while the packed cell volume and total protein (50% and 8.0 g/dL) were consistent with dehydration. The CBC revealed a leukocytosis 17.8 x 10⁹/L (reference range 4.1–15.4 x 10⁹/L), neutrophilia 13.2 x 10⁹/L (reference range 3.0–10.4 x 10⁹/L), and a monocytosis at 4.3 x 10⁹/L (reference range 0–1.2 x 10⁹/L). The serum biochemistry panel was unremarkable.

Abdominal radiographs were repeated at admission approximately 6 hr after the referring veterinarian’s study. The abdominal radiographs showed generalized gaseous dilation of the small intestines, which confirmed the suspicion of a foreign body obstruction and were supportive of a mesenteric volvulus (Figure 1B).

An exploratory laparotomy was performed. During preparation for anesthesia, dog 1 received 1 L of 0.9% NaCl^e IV given over 20 min. Treatment with pantoprazole^f (1 mg/kg IV), ampicillin/sulbactam (30 mg/kg IV), and fentanyl^g (3 mcg/kg/hr IV) was initiated during the preoperative preparation.

Premedication included hydromorphone^h (0.05 mg/kg IV) and midazolamⁱ (0.12 mg/kg IV), and induction was performed with propofol^j (2 mg/kg IV) and ketamine^k (2 mg/kg IV) followed by intubation and maintenance with isoflurane^l and oxygen. The patient was maintained on IV fluids^m (10 mL/kg/hr) during surgery. Fentanyl was administered intraoperatively (3–5 mcg/kg/hr IV). The exploratory laparotomy was performed using a standard ventral midline approach. The small intestines were diffusely and markedly dilated with a dark purple color throughout their length. They were exteriorized, at which time a 270° clockwise rotation of the mesenteric root was noted, which was consistent with a diagnosis of mesenteric volvulus. The mesenteric root was derotated counter clockwise, and the dark purple appearance of the intestines started to resolve. A foreign body was palpated in the distal jejunum. The entire intestinal tract was evaluated and was deemed viable with pulses present throughout the small intestine, some peristalsis, and no thinning of the intestinal walls appreciated. A 2-cm enterotomy was made aboral to the foreign body, and an oblong, fur-covered, stuffed toy was removed. The fluid filling the intestines was suctioned through the enterotomy site, which was closed routinely in a simple continuous pattern using 4-0 polydioxanoneⁿ. A saline test was used to assess for leakage; none was noted. The intestines were again exteriorized and reassessed starting at the oral end. The abdomen was explored, and no other abnormalities were noted. Omentum was sutured to the enterotomy site using a single 4-0 polydioxanone tacking suture in a simple interrupted pattern. The abdomen was lavaged with 5 L of warm 0.9% NaCl. A JP drain^o was placed. Sucralfate suspension^p (2 g total) was injected into the stomach using a 16-gauge needle. The abdomen was closed routinely. Recovery from general anesthesia was uneventful.

Dog 1 recovered in the Intensive Care Unit with complications, including severe diarrhea, hypotensive episodes, hypoproteinemia, electrolyte imbalances, and a suspicion of mild aspiration pneumonia. Enrofloxacin (10 mg/kg IV q 24 hr) was administered immediately after recovery, followed by ampicillin/sulbactam (30 mg/kg IV q 8 hr). Postoperatively, IV crystalloid^q fluids were given (150 mL/hr) initially, which was then adjusted based on fluid losses for 5 days postoperatively. Synthetic colloids^r were initiated the morning after surgery for 3 days postoperatively. Analgesia was provided postoperatively with fentanyl (3–5 mcg/kg/hr) for 4 days, and the dog was transitioned to oral tramadol^s (2.5 mg/kg per os [PO] q 8 hr). The Jackson-Pratt drain was removed 3 days postoperatively. Enteral nutrition was provided using a nasogastric tube^t (14 French x 125 cm) starting 1 day after surgery. The nasogastric tube was removed when the dog started eating 3 days following surgery. Postoperatively, metoclopramide^u (0.08 mg/kg/hr constant rate infusion), pantoprazole (1 mg/kg IV q 12 hr), ondansetron^v (0.2 mg/kg IV q 8 hr), erythromycin^w (promotility dose of 1 mg/kg IV q 8 hr), and maropitant (1 mg/kg IV q 24 hr) were started to assist with gastrointestinal motility, protection, and vomiting. The pantoprazole, erythromycin, and maropitant were discontinued 3 days postoperatively. The metoclopramide was tapered over the following 24 hr and then discontinued.

The dog was discharged 6 days after admission on oral medications, including tramadol (2.5 mg/kg q 8 hr), amoxicillin/clavulanic acid^x (18.5 mg/kg q 12 hr), and enrofloxacin (10 mg/kg q 24 hr) for 14 days. Following discharge, the patient was clinically doing well and was reportedly eating and had a normal attitude. Follow-up suture removal was performed by the referring veterinarian. Dog 1 reportedly did well for 3 mo and then represented to the referring vet for vomiting and anorexia of 48-hr duration. An abdominal exploratory surgery revealed a colonic torsion with severely compromised tissue viability and a partial thickness perforation, as reported by the referring veterinarian. The owners elected humane euthanasia.

Case 2

A 28.2 kg 7 mo old male castrated American bulldog presented to Banfield Pet Hospital with a 2-day history of anorexia, lethargy, and vomiting. The initial clinical sign was anorexia followed by vomiting the following day. The day prior to presentation, the dog was evaluated by a local emergency clinic for persistent anorexia and vomiting. The owner had noted no diarrhea. The dog did have a history of pica and might have eaten part of a chew toy. On presentation to the emergency clinic, the dog was weak, depressed, and estimated to be 7–8% dehydrated with tacky mucous membranes. His temperature was 38.4°C (101.1°F), heart rate was 144 beats per min with good pulse quality, and respiration rate was 24 breaths per min. The dog’s abdomen was soft and nonpainful. Scant brown mucoid stool with streaks of blood was noted on rectal examination.

Initial diagnostics included a parvovirus antigen test^y and abdominal radiographs. The parvovirus antigen test was negative. The abdominal radiographs reportedly showed distention of the gastric lumen with some gas pocketing in a small intestinal loop in the ventral abdomen with a suspicion of material/fabric; however, no obvious obstructive pattern was appreciated. Hospitalization with IV fluids and repeat abdominal radiographs in 12 hr were recommended at that time but were declined due to financial constraints. Subcutaneous fluids (750 mL) were administered prior to discharge. Prompt follow-up with the regular veterinarian was recommended. The owners were instructed to withhold food pending re-evaluation. They were also instructed to withhold water for 6 hr and then offer water in small amounts.

The dog represented to Banfield Pet Hospital 12 hr later. The dog was obtunded with a temperature of 37.9°C (100.2°F), a heart rate of 120 beats per min, a capillary refill time of 3 s, a respiratory rate of 16 breaths per min, and was estimated to be 5–7% dehydrated. On abdominal palpation, a firm section of bowel was noted in the midabdomen, although the dog did not have pain in this area. Rectal exam revealed hemorrhagic loose feces.

A CBC was performed, which revealed no clinically significant abnormalities. A serum biochemistry panel revealed a mild elevation of phosphorus (6.9 mg/dL, reference range 2.5–6.8). A canine pancreas-specific lipase level, giardia ELISA test, and fecal flotation test were negative.

Abdominal radiographs showed numerous loops of small intestine dilated with fluid and gas with a stacked pattern consistent with a small bowel obstruction. A mineral opaque material showing a granular pattern was visible in a segmental dilatation of small intestine in the midabdomen, which was supportive of a foreign body with gas. The colon was distended with gas and fecal material (Figure 2). These radiographic findings were consistent with a foreign body obstruction and, less likely, gastroenteritis.

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Based on the physical examination and diagnostics performed, an abdominal exploratory surgery was recommended. The dog was premedicated with hydromorphone. During the abdominal exploratory surgery, the stomach and colon were noted to be empty. A 270° clockwise intestinal volvulus around the mesenteric root was noted. The intestines were a mild purple color and edematous. The torsion was derotated, and the intestines became a darker purple with many small hemorrhages along the mesentery. The color did not significantly improve, but the intestines maintained peristalsis along their length, and the vessels were found to have strong pulses. A foreign body was located in the distal ileum, and an enterotomy was performed proximal to the cecum. An intact rope toy was removed. The enterotomy was closed with full-thickness sutures using 3-0 poliglecaprone^z in a simple continuous pattern. An overlaying simple continuous layer was then done with 3-0 poliglecaprone. A leak test using saline was performed, and no leaks were noted. An omental patch was performed with 3-0 poliglecaprone using two simple interrupted sutures with one at each end of the incision. A gastropexy was then performed using a routine incisional technique. The abdominal cavity was lavaged with 1 L of a balanced electrolyte solution. Gentamicin^aa (100 mg) was sprinkled over the gastrointestinal tract. The ventral rectus sheath was closed with 0 poliglecaprone using a simple continuous pattern. The subcutaneous layer was closed with 0 poliglecaprone using buried continuous intradermal pattern. The skin was closed with staples.

Intravenous fluids, pain medications, and antibiotics were given perioperatively and postoperatively. These included cefazolin^bb (21 mg/kg IV at induction and then every 90 min during surgery), hydromorphone (0.1 mg/kg IM once postoperatively), carprofen^cc (2 mg/kg subcutaneously once postoperatively), and balanced electrolyte solution (21 mL/kg bolus followed by 10 mL/kg/hr). The day following surgery, the patient was reported to be bright, responsive, and nonpainful upon abdominal palpation. The dog ate a commercial low-fat diet, drank, and took oral medications uneventfully. The following day, the dog passed formed but soft, normal-colored stool and was acting normally. The patient was discharged from the hospital on day 3 on metronidazole (17.7 mg/kg PO q 12 hr), carprofen (2.6 mg/kg PO q 12 hr), and tramadol (1.8 mg/kg PO q 8 hr).

Five days postoperatively, the dog was back to a normal level of activity. The dog was reported to be healthy 18 mo after surgery, according to his veterinarian.

Discussion

These two cases of mesenteric volvulus had several differences from what has previously been reported in the literature with regard to signalment, pathogenesis, and prognosis. Both dogs had clinical signs for several days leading up to surgery, were relatively cardiovascularly stable, and survived to discharge. These two dogs were under 1 yr of age, which has been rarely reported previously, as mesenteric volvulus is a condition that typically affects adult dogs.² The underlying cause of the mesenteric volvulus in these cases appeared to be an obstructive foreign body, even though most cases of mesenteric volvulus have no identifiable cause.³

Both of these dogs had a longer duration of clinical signs, and both survived to discharge with surgical intervention. Case 1 had anorexia and vomiting for 7 days, while case 2 was vomiting and anorexic for 2 days. The previously reported mesenteric volvulus cases in the literature report over 90% of cases present with peracute to acute clinical signs.^2–7 Typically, mesenteric volvulus is a fatal condition with death occurring 12–18 hr after the first clinical signs, and mortality approaches 100%, with only one study reporting a 40% survival with surgical correction within 1 hr of admission.^2,4–7 Rapid death occurs due to the vascular obstruction, intestinal ischemia, and a combination of hypovolemic, septic, and cardiogenic shock.⁸ In previous reports of mesenteric volvulus, clinical signs were present for less than 12 hr in the majority of cases.^2–6 Those reported cases with peracute to acute clinical signs and a history of gastrointestinal disease that survived the trip to the hospital have marked distention of the gastrointestinal tract, which is consistent with the dogs in this case study, even though these dogs had clinical signs that were more chronic.⁵ When dogs present with acute or chronic clinical signs and radiographs reveal marked gastrointestinal dilation, radiographic changes alone cannot identify the exact etiology.⁵ These abnormalities could be due to an adynamic ileus or mechanical obstruction, which have several differential diagnoses, including foreign body, mass, intussusception, or mesenteric volvulus.⁵ Therefore, the recommendation is an emergency laparotomy when radiographs suggest an obstructive or adynamic ileus whether or not there is an identifying etiology and whether or not the clinical signs are acute or chronic.^2,5 In case 1, an immediate exploratory laparotomy was not performed by the referring veterinarian following radiographs since the barium did not outline an obvious foreign body. In case 2, an exploratory laparotomy was not initially performed due to financial constraints of the owners.

The patients presented here were not in shock at presentation based on physical examination and an insignificantly elevated serum lactate, which may indicate either an intermittent volvulus or a less severe volvulus that did not cause severe vascular compromise. Typically, the initial diagnosis of a mesenteric volvulus can be difficult because of the vague clinical signs and rapid decline seen on presentation.² There are no pathognomonic clinical signs, but common signs include abdominal distension, hematochezia, vomiting, abdominal pain, and severe shock (pale mucous membranes, tachycardia, weak pulses, etc.).^1–3,5 These clinical signs are secondary to the strangulating mechanical obstruction and ischemia of the small intestines.¹ The ischemia can result in bowel necrosis, toxin release, and hypovolemic/septic shock, which leads to peracute to acute clinical signs that rapidly progress secondary to the vascular obstruction, intestinal ischemia, and endotoxic/hypovolemic shock.^2–4,8 Case 1 had radiographs that were taken by the referring veterinarian approximately 6 hr prior to admission. These radiographs were reviewed as strongly suggestive of a mesenteric volvulus, although clinical signs remained mild until exploratory laparotomy despite a 270° volvulus. There is only one previous report of a chronic mesenteric volvulus of a dog that had chronic clinical signs of vomiting, diarrhea, and weight loss that did not present with clinical signs of shock.³ That patient was a 4 yr old Bernese mountain dog, which underwent an exploratory laparotomy at which time a mesenteric volvulus was identified and surgically corrected, and the dog went on to do clinically well.³ These two cases differ from that previous report since the previous report had a partial mesenteric volvulus, and there was a longer duration of the clinical signs.

As previously mentioned, mesenteric volvulus is often a fatal disease, with only a handful of cases reported to have survived.^2–8 Animals that have survived a mesenteric volvulus were incidentally diagnosed during a celiotomy for another problem, had rotation limited to 180°, had viable intestine after derotation, and were operated on within a few hours of occurrence.^2,7–9 Even for dogs that survive long enough to receive preoperative aggressive management of shock and surgical intervention, many are euthanized during surgery for generalized intestinal necrosis that is unable to be resected at the time of surgery.^2,4,5 In both of the cases reported here, the mesenteric volvulus was resolved with surgical intervention, and the intestine in both cases remained viable and did not require a resection and anastomosis at the time of surgery even though a 270° volvulus was found in both cases.

Dogs with mesenteric volvulus that do not require a resection and anastomosis and receive prompt medical attention appear to have a higher survival rate.² In a study in which there were 5 survivors out of 12 cases, only 1 survivor received a resection and anastomosis.² However, there was still over a 50% mortality rate noted in that report.² Even when dogs survive surgery for a mesenteric volvulus, they are still at risk of death after surgery due to reperfusion injury from the tissue damage, with most of these injuries taking place within the first 5 min of reperfusion.² There are two reports of incidentally found mesenteric volvulus that were successfully treated: one patient was diagnosed during surgery for the urinary bladder, and a dog was diagnosed after presenting with abdominal pain for several days.^7,9 There is also a case report of a dog that had chronic gastroenteritis that was diagnosed with a mesenteric volvulus during an abdominal laparotomy.³ During the laparotomy, the volvulus was not tight, the rotation was limited and not enough to cause marked impedance of blood flow, and it was suspected to have caused either a motility disorder or intermittent mild ischemia.³ In a case study involving nine dogs, the only surviving dog had a rotation limited to 180° and was diagnosed incidentally during an abdominal exploratory surgery.⁷ This is in comparison to the cases presented here in which there were chronic clinical signs, but the rotation was greater than 180°, and they were not diagnosed incidentally.

Both of these dogs were less than 1 yr of age, although mesenteric volvulus does occur most commonly in adult dogs.^2,4–7 Mesenteric volvulus is typically diagnosed in dogs with a median age range of 3.5 yr (25 days to 9 yr), with less than a half a dozen cases reported to be less than 1 yr of age.^2–7,10 This can likely be attributed to the fact that the underlying conditions associated with a mesenteric volvulus are typically also associated with adult dogs.^{2–5,7,11–12}

Due to the relationship between mesenteric volvulus and the motility of the gastrointestinal tract, foreign body obstruction is a plausible cause.⁷ Other, less common causes of mesenteric volvulus that could be associated with a young dog are intussusception and parvoviral infection, which also affect gastrointestinal motility.^2,11 Mesenteric volvulus has been associated with some other diseases of gastrointestinal motility such as exocrine pancreatic insufficiency, concurrent gastric dilatation-volvulus, inflammatory bowel disease, ileocolic intussusception, ileal carcinoma, previous abdominal exploratory surgery, plasmocytic-lymphocytic enteritis, and consumption of a large amount of food over a short period of time.^2–4,6,7,12

Concurrent intestinal foreign body obstruction was noted in both of these dogs with a history of several days of vomiting, which may indicate that the foreign body was present prior to, and may have predisposed the dogs to, a mesenteric volvulus due to its effect on intestinal motility. A foreign body is a reported cause of a mesenteric volvulus, but despite an extensive literature search, the authors could not find the origin of this statement.^2,3,7 Therefore, this report represents the first published evidence of foreign body obstruction with concurrent mesenteric volvulus. With an obstructive foreign body, the bowel distends with gas and fluid and has periodic bursts of neuromuscular activity that result in peristaltic rushes.¹³ These periods of hyperactivity are then followed by quiescent periods of varying duration.¹³ It has been shown in domestic animals, other than dogs, that diets that result in excessive gas production or hypermotility, or both, promote bowel displacement.¹⁴ This has been suspected in whey-fed pigs, in which excessive gas production led to bowel displacement and volvulus.^7,14 A study was performed on 50 pigs that ate a whey diet and had abdominal distension due to excessive gas production; 47 of them had a volvulus present at necropsy.¹⁴ Another example is gastric dilatation and volvulus, the stomach is dilated with gas and will rotate on its axis in a similar way to what occurs with a mesenteric volvulus.¹ The underlying cause of this condition is still not well understood, but there is suspicion that the gas dilation occurs prior to the volvulus due to the fact that a gastropexy helps to prevent this condition.¹ A foreign body creating a similar intestinal ileus and gas dilation could also then predispose a patient to a mesenteric volvulus.

Several unconventional treatments were used in these two cases. In case 1, sucralfate suspension was injected into the stomach because of concern that dog 1 would not be able to be administered oral medications following surgery and yet was at a high risk of mucosal ulceration. Mucosal ulceration can occur with mesenteric volvulus due to mucosal epithelial sloughing due to compromised blood flow.¹³ In case 2, a two-layer closure was used for the enterotomy to reportedly minimize potential intestinal leakage. Although it may decrease the risks of dehiscence, it also may initially increase the risk of stricuture.¹⁵ A simple continuous pattern provides good apposition and is recommended for the gastrointestinal tract.⁸ It has been shown that submucosal apposition is poorer with a two-layer closure than a single-layer closure.^1,15 A two-layer closure can also result in avascular necrosis of an inverted cuff of tissue, prolonging wound healing and increasing intraluminal protrusion of tissue.^1,15 A single-layer closure is therefore recommended in the small intestine.¹ Poliglecaprone was used to suture the ventral rectus sheath in case 2, reportedly because this was the only suture material available at the practice at that time. This suture material is not recommended for enteric closure because of its quick loss of tensile strength, with 70–80% of its strength lost over the first 2 wk.¹ Lastly, the use of intraperitoneal gentamicin in case 2 is questionable following the abdominal lavage. This was reportedly done out of concern for bacterial translocation. A study was previously performed on the effectiveness of intraperitoneal gentamicin used once daily in peritoneal dialysis patients.¹⁶ This showed that the peak serum gentamicin levels obtained were lower than the recommended dose and had less therapeutic benefit.¹⁶ The recommendation is to not use intraperitoneal gentamicin during surgery. However, both short- and long-term follow up is available for case 2, with no signs of stricture or persistent gastrointestinal signs.

Conclusion

These two cases support the association between a foreign body and a mesenteric volvulus. Although unusual, the rule out of mesenteric volvulus should be included in young patients with chronic gastrointestinal signs if the radiographic signs are consistent with a mesenteric volvulus. Mesenteric volvulus should be confirmed with an exploratory surgery.