Introduction

Intestinal volvulus is the pathologic twisting of a section of bowel around its mesenteric attachment site.^1–4 Small and large intestinal volvulus is most common in horses, cattle, swine, and humans.^2,3 The condition occurs uncommonly in dogs and cats, with small intestinal volvulus occurring more commonly than large intestinal volvulus.^1–3,5,6

Intestinal volvulus is a life-threatening condition, which warrants medical stabilization and surgical intervention.^2,5 This pathologic condition results in luminal obstruction and vascular compromise, leading to ischemia, necrosis of the affected bowel segment, and subsequent circulatory shock.^2,4,5 The exact etiology of intestinal volvulus is unknown, and it has been associated with numerous underlying causes.^1,2,4,5,7,9 The severity of clinical signs is relative to the degree and duration of the volvulus, and clinicopathologic findings are often nonspecific.^1,3,7,10

Radiographically, severe gas distention of the affected portion of bowel is noted, which may be accompanied by loss of serosal detail due to peritoneal effusion.^10,11 When evaluating radiographs for large intestinal volvulus, the gas distention is often accompanied by an inability to trace the large intestine into the pelvic canal, as it is often in an abnormal location within the abdomen.^10,11 When describing small intestinal volvulus radiographically, while the entire small intestinal tract is severely gas-distended, the stomach and large intestine are usually not dilated.¹⁰ Exploratory laparotomy is often necessary to confirm the diagnosis of intestinal volvulus, as it is difficult to definitively diagnose based on clinical examination and radiography alone.^2,7,10

Successful management requires decompression and anatomic correction of the affected bowel, followed by intensive supportive care.^2,5,7 Further surgical treatments include resection and anastomosis of any devitalized intestinal segments, followed by left abdominal wall colopexy if the affected segment includes large intestine.^1,3,5

Despite early surgical intervention, the condition may result in death as a result of endotoxemia and circulatory shock.² According to the previous literature, both small and large intestinal volvulus are associated with an extremely high mortality rate, with only a few reports of successful management; thus, owners are often given a poor prognosis for survival when one of these conditions is suspected.^1,2,4,5

When comparing the literature describing outcome in dogs with large versus small intestinal volvulus, it is evident that the prognosis for large intestinal volvulus is much more favorable than for small intestinal volvulus.^1–3,4,5,7 Four case reports describing small intestinal volvulus in a total population of 19 dogs revealed that only one of the 19 dogs survived and was discharged from the hospital.^1,2,7

Previous literature described survival to discharge in six of eight dogs with large intestinal volvulus.^1,3,5,8 A recent study, however, described a 100% survival rate in six dogs with large intestinal volvulus.⁹ Combining the results from all of the literature describing large intestinal volvulus in dogs leads to an overall survival to discharge in 12 of 14 dogs with large intestinal volvulus, thus depicting a more favorable outcome in dogs with large intestinal volvulus compared to small intestinal volvulus.

The objectives of this study were to evaluate the outcome of dogs with surgically corrected large versus small intestinal volvulus between October 2009 and February 2014. It was hypothesized that, in accordance with previous literature, the outcome for dogs with large intestinal volvulus would be better than for animals with small intestinal volvulus.

Materials and Methods

Medical records from New England Animal Medical Center, Matthew J. Ryan Veterinary Hospital at the University of Pennsylvania, Ocean State Veterinary Specialists, Red Bank Veterinary Hospital, and Cape Cod Veterinary Specialists were searched for dogs that were diagnosed with large and small intestinal volvulus between October 2009 and February 2014.

Criteria for inclusion in this study were that dogs had to have evidence of either large or small intestinal gas distention on radiographs and have a confirmation of either large or small intestinal volvulus on abdominal exploratory. Each medical record was reviewed, and the following information was examined: signalment, previous medical history, presenting complaint, clinical signs, clinicopathologic data, radiology results, surgical treatment date and description, length of hospitalization, and clinical outcome. All owners were contacted via phone prior to the writing of this paper to inquire on the status and health of each dog in order to determine outcome following hospital discharge.

Results

Fifteen dogs met the inclusion criteria between October 2009 and February 2014. There were three Labrador retrievers, six German shepherd dogs, two Great Danes, one boxer, two mixed breed dogs, and one American pit bull. There were six castrated males, six intact males, two spayed females, and one intact female. Age of affected dogs ranged from 3 mo to 13 yr (median, 5 yr). Weight of the affected dogs ranged from 3.5 kg to 71 kg (median, 33.4 kg). Of these 15 dogs, nine were diagnosed with large intestinal volvulus, and six with small intestinal volvulus.

For the large intestinal volvulus group, breeds affected consisted of three Labrador retrievers, five German shepherd dogs, and one Great Dane. There were five castrated males and four intact males. No females were represented. Age of the affected dogs ranged from 2 yr to 13 yr (median, 5 yr). Weight at the time of diagnosis ranged from 23.5 kg to 49.5 kg (median, 34.2 kg) (Table 1).

Table 1 Summary of Nine Dogs Diagnosed with Large Intestinal Volvulus

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All dogs with large intestinal volvulus were presented for an acute onset of clinical signs related to the gastrointestinal tract. The signs varied among individual dogs, but most commonly included vomiting (7/9), tenesmus (5/9), or lethargy (3/9). Other less common presenting clinical signs included inappetance (2/9), diarrhea (2/9), nonproductive retching (1/9), and distended abdomen (1/9). No animals had a history of previous small or large intestinal volvulus, and no animals had a history of prior gastropexy (Table 1).

A total of six dogs were diagnosed with small intestinal volvulus. The breeds affected consisted of one German shepherd dog, one Great Dane, one boxer, two mixed breed dogs, and one American pit bull. There was one castrated male, two intact males, two spayed females, and one intact female. (50% males, 50% females). Age of the affected dogs ranged from 3 mo to 7 yr (median, 5 yr). Weight at the time of diagnosis ranged from 3.5 to 71 kg (median, 29.3 kg) (Table 2).

Table 2 Summary of Six Dogs Diagnosed with Small Intestinal Volvulus

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Four of the six dogs with small intestinal volvulus presented for an acute onset of vomiting (4/6). Other presenting clinical signs included panting and pacing (1/6), anorexia (1/6), decreased appetite (1/6), diarrhea (1/6), tenesmus (1/6), and excessive vocalizing (1/6) (Table 2).

All cases were admitted for diagnostics and supportive care. Diagnostics included abdominal radiographs in all cases. For the large intestinal volvulus group, all radiographs were suspicious for large intestinal volvulus, with the exception of one case in which the radiographs were more consistent with small intestinal volvulus than large intestinal volvulus (Figures 1, 2). For the small intestinal volvulus group, five of the six cases had small intestinal volvulus listed as a primary differential diagnosis. Radiographs on one of the six cases listed small intestinal foreign body as the most likely diagnosis, and did not list volvulus as a rule-out (Figures 3, 4).

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Laboratory data included packed cell volume, total solids and an electrolyte panel on all patients. All dogs had a complete blood count and chemistry panel performed; however, not all results were available. Mild clinicopathologic abnormalities were noted; however, none were specific for large or small intestinal volvulus. The laboratory results for case 7 of the large intestinal group and case 1 of the small intestinal group were unavailable (Tables 3, 4).

Table 3 Clinicopathologic Data for Nine Dogs Diagnosed with Large Intestinal Volvulus

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Table 4 Clinicopathologic Data for Six Dogs Diagnosed with Small Intestinal Volvulus

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All dogs were placed under general anesthesia, and an abdominal exploratory was performed. At abdominal exploratory for the large intestinal volvulus group, a large, rotated, gas-dilated large intestine was noted, and the rest of the abdominal exploratory was normal in all dogs. The large intestinal volvulus was corrected in all dogs. Eight of the nine dogs had a left abdominal wall colopexy performed. Seven had the colopexy performed at the time of the initial surgery, and one (case 6) had the colopexy performed at a later surgery (18 days later) due to the poor condition of the bowel at the initial surgery. Two animals (cases 7 and 9) had a gastropexy performed at the time of surgery. In one animal (case 9), this was in addition to the colopexy, and in the other (case 7), it was in addition to a colonic resection and anastomosis. This dog required an intestinal resection and anastomosis, because a large portion of the colon, ileum, and jejunum were devitalized. The devitalized portion of bowel was resected and a jejunocolic anastomosis was performed. A colopexy was not performed in this dog (Table 5, Figures 5, 6).

Table 5 Surgical Procedure and Outcome for Nine Dogs Diagnosed with Large Intestinal Volvulus

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For the small intestinal volvulus group, a rotated, gas-dilated small intestine was noted at surgery. With the exception of case one, all animals had some degree of small intestinal necrosis noted. The rest of the abdominal exploratory was normal in all animals. In case one, the bowel was very dark purple, but no obvious necrotic areas were noted. In this patient, the volvulus was corrected and no further surgical treatment was performed. In three animals (cases 2, 3, and 6), the entirety of the small bowel was necrotic, the owners were contacted from the operating room, and it was elected to humanely euthanize the animal while under anesthesia. For two animals (cases 4 and 5), an intestinal resection and anastomosis was performed to remove the necrotic bowel.

All dogs in both groups who recovered from surgery were maintained in the hospital postoperatively. All were maintained on supportive care including intravenous fluid therapy, pain medication, and antibiotics. Other treatments varied by institution.

For the large intestinal volvulus group, all dogs were discharged from the hospital. The duration of hospitalization ranged from 1 day to 4 days (median, 2 days). Two dogs were lost to follow-up at 12 days and 65 days postoperatively. Of the seven dogs whose owners were available for phone conversation at the time of writing this paper, all seven were alive and doing well. The number of days from surgery to phone conversation ranged from 74 days to 955 days postoperatively (median, 118 days) (Table 5).

For the small intestinal volvulus group, only one of the six animals (case 4) was discharged from the hospital (1.5 days post operatively) and was alive at last phone follow-up 730 days post operatively. Of the other two animals that were not euthanized at surgery, one (case 1) was euthanized early the following morning due to uncontrollable hypotension and pain. The other animal (case 5) remained in the hospital and was euthanized 3 days later after she became febrile and was found to have a septic peritoneal effusion (Table 6).

Table 6 Surgical Procedure and Outcome for Six Dogs Diagnosed with Small Intestinal Volvulus

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Discussion

Intestinal volvulus is an uncommon but potentially fatal medical condition in dogs.^1,2 The canine intestine has a mesentery that runs its entire length, with relatively short mesenteric attachments, attributing to the overall lower incidence of intestinal volvulus in canine patients.^2,7,12 While the condition is rare in dogs, previous literature indicates that small intestinal volvulus appears to occur more commonly than large intestinal volvulus.^2–4 In the present study, a medical records search revealed more cases of large intestinal volvulus than small intestinal volvulus.

The exact etiology of the condition remains unknown.^2,4,7 Previous reports indicated that pre-existing or concurrent exocrine pancreatic insufficiency or lymphyplasmacytic enteritis may be present in dogs with intestinal volvulus, and a recent report indicated an increased likelihood of large intestinal volvulus in dogs with previous gastropexy following gastric dilatation and volvulus.^2,4,7–9 In the current case series, however, no biopsies were obtained at the time of surgery, and none of the dogs had previous gastropexies performed.

Intestinal volvulus is a life-threatening condition that warrants medical stabilization and surgical intervention.^2,5 Diagnosis is often challenging in the clinical setting, as clinical signs, radiographs, and laboratory findings are often nonspecific.³ Clinical signs may include vomiting, tenesmus, and abdominal distension, which are all nonspecific signs of gastrointestinal disease.¹² We found in our case series that vomiting was the most common clinical sign for animals with intestinal volvulus, while animals with large intestinal volvulus commonly also presented for tenesmus.

As found in previous reports, laboratory findings in animals with intestinal volvulus are often nonspecific and include leukocytosis and hemoconcentration, which is consistent with our results.^7,10 Radiographs often reveal gas or fluid dilation of the affected segment of bowel. A definitive diagnosis of intestinal volvulus often cannot be made based on radiographs.^2,3,5 Of all of the animals in the current study, radiographic interpretation by a board-certified radiologist was suspicious for intestinal volvulus in five of the six cases of small intestinal volvulus and eight of the nine cases of large intestinal volvulus; however, none of the radiological interpretations were definitive.

None of the animals in the current study had a definitive diagnosis of intestinal volvulus until surgery. In the small intestinal volvulus group, three dogs were euthanized at the time of surgery due to extensive bowel necrosis, and two of the remaining three required some degree of small intestinal resection and anastomosis. For the large intestinal volvulus group, seven of the nine were successfully managed with derotation of the colon and colopexy at the time of initial surgery. One animal required a second staged procedure in order to perform the colopexy, and one required an intestinal resection and anastomosis.

The reported mortality rate associated with intestinal volvulus is high, and because the literature contains only a few reports of successful management, owners are often given a guarded prognosis.^2,5 Combining the results from all of the previous literature describing large intestinal volvulus in dogs leads to an overall survival to discharge in 12 of 14 dogs with large intestinal volvulus. This can be compared to the previous literature describing outcome in animals with small intestinal volvulus, in which only one out of 19 dogs survived and was discharged from the hospital, thus depicting a more favorable outcome in dogs with large intestinal volvulus compared to small intestinal volvulus.^1–5,7

In the current study, survival in dogs with large intestinal volvulus was 100%. Two dogs were lost to follow-up at 12 and 65 days postoperatively. The owners of seven dogs were available for phone follow-up, and all dogs were alive. This was compared to the outcome of a time-matched population of dogs with small intestinal volvulus in which only one animal (16%) survived to discharge. This documents that with medical stabilization and surgical correction, the survival for dogs with surgically corrected large intestinal volvulus is excellent, whereas survival for dogs with small intestinal volvulus is poor, thus supporting the previous literature.

While a preoperative diagnosis of intestinal volvulus is often challenging, intestinal volvulus should be suspected in any animal that presents with acute vomiting and/or tenesmus, and whose radiographs reveal severe gas distention of intestinal loops. While it is not always easy to determine whether the distended intestinal loops are large or small intestine radiographically, an abdominal exploratory should be performed in order to make a definitive diagnosis and provide surgical correction of the volvulus.

Conclusion

Successful management of large intestinal volvulus is possible, and this study suggests that the survival rate is very good, compared to the survival rate for dogs with small intestinal volvulus, which is poor. Given this information, if intestinal volvulus is suspected based on clinical history and radiographic findings, surgical exploratory should be performed in order to confirm the diagnosis and provide owners with an appropriate prognosis.