Spontaneous Reduction of Intestinal Intussusception in Five Young Dogs
Five, 3- to 8-month-old dogs had clinical and ultrasonographic findings consistent with intestinal intussusception, but findings were negative on exploratory celiotomy. Ultrasonography had revealed a target-like mass (median maximal diameter 25 mm) on transverse section and multiple hyperechoic or hypoechoic parallel lines (median length 36.8 mm) on longitudinal section. Blood flow in the intussuscepted bowel was detected in most of the cases. In dogs with similar findings, the authors recommend ultrasonographic reexamination of the abdomen after general anesthesia (but before surgery) to exclude spontaneous reduction of the intussusception.
Introduction
Intestinal intussusception is a common type of intestinal obstruction in young dogs. Clinical signs vary in severity depending on the duration of signs and the degree of intestinal and vascular obstruction. Clinical signs may include vomiting, bloody or nonbloody diarrhea, and abdominal pain.1–4 Diagnosis is traditionally based on history and physical examination, especially palpation of a sausage-shaped abdominal mass.
Abdominal ultrasonography has been shown to be a reliable means for diagnosis of intestinal intussusception, revealing characteristic signs that may result from juxtaposition of the intestinal wall layers.5–7 On transverse section, the characteristic ultrasonographic signs include a target-like mass consisting of multiple concentric rings completely surrounding a hyperechoic center. These rings consisted either of hyperechoic or hypoechoic elements. Longitudinal sections generally reveal multiple hyperechoic and hypoechoic parallel lines.5–7 Ultrasonography that has been evaluated using these criteria has demonstrated a high sensitivity (100%), specificity (97.8%), and accuracy (94.8%) in the diagnosis of intestinal intussusception in young dogs.7
Ultrasonographic diagnosis is confirmed by exploratory celiotomy. Surgical intervention (including manual reduction or resection and anastomosis of the intussuscepted bowel) is considered the definitive treatment for intestinal intussusception in small animals.1–4 However, spontaneous reduction of true intussusceptions diagnosed by ultrasonography (before any treatment) has been reported.8 This has been well documented in children and has been postulated in only three dogs, in which the clinical and ultrasonographic diagnoses of intestinal intussusception were not confirmed on exploratory celiotomy.4,7,9–12
The case series reported here describes five young dogs with spontaneous reduction of intestinal intussusception. Their histories, findings (radiographic, ultrasonographic, and surgical), and clinical outcomes are discussed.
Case Reports
All cases were associated with acute enteritis or gastroenteritis, and intestinal intussusception was the tentative diagnosis. See the Table for the signalment and the clinical, radiological, ultrasonographic, and surgical findings for these five dogs.
Treatment was similar for all dogs, unless otherwise indicated. Ultrasonography was performed using the same procedure and equipment described for case no. 1. The dosages and administration of premedication, anesthesia, and postoperative medication were identical to those used in case no. 1, unless otherwise noted. The types and dosages of postoperative analgesia varied among cases, as noted below.
Initial exploratory surgeries uncovered no signs of intestinal intussusception, adhesions, or hemorrhage in the intestinal wall. Enteroplication was not routinely performed because of surgeon preference. In all cases, the abdominal cavity was lavaged with warm saline before routine closure.
Case No. 1
A 3-month-old, male German shepherd dog was presented with a 2-day history of vomiting and frank hemorrhagic diarrhea. A mass was detected on abdominal palpation, and plain abdominal radiographs revealed a tubular viscus [see Table].
Ultrasonographic examination was performed using a 7.5-MHz mechanical sector transducer and a color and pulsed Doppler unit.a Ultrasonographic evaluation of the abdomen revealed mild intestinal hypermotility, mild enlargement of the mesenteric lymph nodes, and a target-like structure of 26 mm in maximal diameter. This structure consisted of multiple concentric rings completely surrounding a linear hyperechoic center. These rings consisted either of hyper- or hypoechoic elements. The overall width of the concentric rings was 9 mm [Figure 1A]. Longitudinal sections revealed multiple hyperechoic or hypoechoic parallel lines measuring 42 mm in length and forming a trident-like configuration [Figure 1B].
The color Doppler unit was used to detect arterial and venous blood flow within the intussuscepted bowel. A constant low-wall filter (100-Hz), a low-velocity scale (pulse repetition frequency at 1500 Hz), and high color sensitivity (color flow power 80%) were applied to detect low-velocity flow.13,14 When a color Doppler signal was identified, pulsed-Doppler spectral waveforms were obtained to confirm that the color signal was generated by vascular flow and not as an artifact of movement.
An exploratory celiotomy was performed 12 hours after ultrasonographic examination. The dog was premedicated with acetylpromazineb (0.05 mg/kg intramuscularly [IM]) and butorphanolc (0.1 mg/kg IM). Anesthesia was induced with propofold (2 to 3 mg/kg intravenously [IV]) and maintained with isofluranee in oxygen. No abnormalities were seen on abdominal exploration. Postoperative analgesia consisted of administration of morphine (0.5 to 1 mg/kg IM) and fentanylf (2 to 4 μg/kg IV) for the first 24 hours. Intravenous carprofeng was administered 30 minutes before surgery (4 mg/kg) followed by 2 mg/kg given orally twice daily for 4 days.
The dog was discharged from the hospital 2 days after surgery but showed clinical signs of intestinal obstruction 6 days after the initial diagnosis. A second abdominal ultrasonographic examination had results similar to those of the initial ultrasonographic examination. The maximal diameter of the target-like mass was 37 mm; the lengths of the parallel lines were 100 mm; and a semilunar hyperechoic center was surrounded by concentric rings. Exploratory celiotomy documented enteroenteric intussusception, and intestinal resection and anastomosis were performed. The dog was doing well 1 month after surgery.
Case No. 2
A 3-month-old, female German shepherd dog was presented with a clinical diagnosis of acute enteritis/gastroenteritis characterized by vomiting and diarrhea for 2 days. Abdominal ultrasonographic imaging was performed after a mass was detected on abdominal palpation. Plain abdominal radiographs were not performed.
Abdominal ultrasonography revealed mild enlargement of the mesenteric lymph nodes and a target-like, concentricring structure of 19 mm in maximal diameter. This structure was similar in appearance to that described in case no. 1. The overall width of the concentric rings was 8 mm. Multiple hyperechoic and hypoechoic parallel lines of 26 mm in length were found on longitudinal section. Arterial and venous blood flow within the intussuscepted bowel was detected using the Doppler unit described in case no. 1 [Figure 2].
Premedication consisted of acetylpromazine (0.05 mg/kg IM). Anesthesia was induced with thiopentone sodiumh (10 mg/kg IV) and maintained with isoflurane in oxygen. Exploratory celiotomy performed 1 hour after ultrasonographic examination revealed a normal intestinal tract and mild enlargement of the mesenteric lymph nodes. Postoperative analgesia consisted of administration of fentanyl (2 to 4 μg/kg IV) for the first 24 hours. The dog was discharged from the hospital 1 day after surgery and was in good health 1 month later.
Case No. 3
A 5-month-old, female, mixed-breed dog was presented with a clinical diagnosis of acute enteritis/gastroenteritis characterized by vomiting and diarrhea for 3 days. Abdominal ultrasonographic imaging was performed after a mass was detected on abdominal palpation. Plain abdominal radiographs were within normal limits.
Ultrasonography revealed mild enlargement of the mesenteric lymph nodes and the characteristic target-like structure described earlier. This structure was 27 mm in maximal diameter, with an overall ring width of 9 mm. Multiple hyperechoic and hypoechoic parallel lines of 46 mm in length were noted on longitudinal section [Figure 3]. Doppler examination was not performed.
Exploratory celiotomy performed 12 hours after ultrasonographic examination revealed a normal intestinal tract and mild enlargement of the mesenteric lymph nodes. Postoperative analgesia consisted of pethidine (3 to 6 mg/kg IM) and fentanyl (2 to 4 μg/kg IV) for the first 24 hours. The dog was discharged 1 day after surgery and was reported to be healthy approximately 1 month later.
Case No. 4
An 8-month-old, male, mixed-breed dog was admitted with a 1-day history of vomiting. Amass was detected on abdominal palpation. Plain abdominal radiographs revealed localized dilatation of the small intestine.
Abdominal ultrasonography revealed mild enlargement of the mesenteric lymph nodes and a target-like structure of 24 mm in maximal diameter. This structure was similar in appearance to that described in case no. 1. The overall width of the concentric rings was 8 mm. Longitudinal sections revealed multiple hyperechoic and hypoechoic parallel lines of 26 mm in length, forming a trident-like configuration [Figure 4]. Arterial and venous blood flow was detected within the intussuscepted bowel.
Exploratory celiotomy performed 1 hour after ultrasonographic examination revealed a normal intestinal tract and mild enlargement of the mesenteric lymph nodes. Postoperative analgesia consisted of morphine (0.5 to 1 mg/kg IM) and fentanyl (2 to 4 μg/kg IV) for the first 24 hours.
This dog showed clinical signs of intestinal obstruction approximately 48 hours after the initial diagnosis and exploratory surgery. A second abdominal ultrasonographic examination revealed signs similar to those of the initial ultrasonographic examination. The maximal diameter of this second target-like mass was 24 mm, with 50-mm parallel lines and a characteristic, linear hyperechoic center surrounded by concentric rings. A second exploratory celiotomy documented enteroenteric intussusception, which was manually reduced and followed by enteroplication. One month after surgery, the dog was doing well.
Case No. 5
A 3-month-old, male, mixed-breed dog was presented with a 2-day history of vomiting and diarrhea. A mass was detected on abdominal palpation. Plain abdominal radiographs were within normal limits.
Abdominal ultrasonography revealed mild enlargement of the mesenteric lymph nodes and a target-like structure of 29 mm in maximal diameter. This structure was similar in appearance to that described for case no. 1. The overall width of the concentric rings was 10 mm [Figure 5]. Multiple hyperechoic and hypoechoic parallel lines of 44 mm in length were noted on longitudinal section. Arterial and venous blood flow within the intussuscepted bowel was detected using the Doppler unit described for case no. 1.
Exploratory celiotomy performed 1 hour after ultrasonographic examination revealed no signs of intestinal intussusception and mild enlargement of the mesenteric lymph nodes. Postoperative analgesia consisted of morphine (0.5 to 1 mg/kg IM) and fentanyl (2 to 4 μg/kg IV) for the first 24 hours. One month after surgery, the dog was doing well.
Discussion
Spontaneous reduction of intestinal intussusception has been commonly described in children. In one study, spontaneous reduction was described in 14% of the children in whom hydrostatic reduction with barium was not successful, but an intussusception was not found during surgery.9 In another study of children, spontaneous reduction of intestinal intussusception occurred in about 17% of all cases of intussusception seen over a 6-year period.10
Spontaneous reduction of intestinal intussusception has also been described in dogs. It was the presumptive diagnosis in three dogs with clinical and ultrasonographic diagnoses of intestinal intussusception but with negative findings on exploratory celiotomy. Detailed data for these cases, however, were not available.4,7,12
The five dogs in the present study were part of a total of 63 young dogs with clinical and ultrasonographic diagnoses of intestinal intussusception seen by the authors over a 6- year period. The clinical data for these five cases were similar to those described in young dogs with intestinal intussusception confirmed during surgery.7 However, the duration of clinical signs in dogs with spontaneous reduction (median 2 days, range 1 to 3 days) was shorter than that in dogs with intestinal intussusception confirmed at surgery (median 8.63 days, range 3 to 20 days). Longer duration of clinical signs may result in adhesions of the serosal surfaces of the intussuscepted bowel, making spontaneous reduction impossible.2,13
In children, spontaneously reduced intestinal intussusceptions have generally been asymptomatic, so that documentation of an intussusception was an incidental finding.10 This contrasts with the situation in dogs, in which no statistically significant correlation has been found between duration of clinical signs and the presence of adhesions.1
The canine intestinal wall normally measures up to 3 mm in thickness on ultrasonographic examination. Therefore, the overall width of the concentric rings created by the juxtaposition of the wall of the intussuscipiens and the wall of the inner and outer intussusceptum should not be >9 mm. Thicker peripheral rings suggest edema formation, which might complicate the intussusceptions.7 The median overall ring width of 8.8 mm (range 8 to 10 mm) in the current case series may reflect the absence of congestion in the invaginated intestine, which allowed spontaneous reduction to occur. This is consistent with the situation in people, in whom the presence of a thin (<7.5 mm) external hypoechoic ring is usually associated with a reducible intussusception.15
In dogs, the diameter of the target-like mass created by the juxtaposition of the intestinal wall layers should normally be approximately 18 mm, but edema formation and entrapped mesentery may result in increased diameter. The 25-mm (range 19 to 29 mm) median maximal diameter reported in the current case series suggests relatively small and uncomplicated intussusceptions, although lack of relative data in dogs prevents any firm conclusions. This is consistent with the situation in children, in whom asymptomatic small-bowel intussusceptions had smaller diameters (median 18 mm) than did symptomatic intussusceptions (median 28 mm).10 In symptomatic cats undergoing surgical treatment for intestinal intussusception, the diameter of the target- like structure ranged from 16 to 32 mm.16
The characteristic target-like structure (i.e., hyperechoic and hypoechoic concentric rings surrounding a hyperechoic center) found in the current case series has been reported in most young dogs with intestinal intussusception and acute enteritis or gastroenteritis.7 The hyperechoic center has generally been described in the literature as having a circular, G-shaped, reversed G-shaped, or semilunar appearance.7 Such masses have been surgically defined as consisting of mesenteric fat and compressed intussusceptum.7 This contrasts with the present situation, in which the hyperechoic center had a linear shape representing the opposing mucosal surfaces of the inner intussusceptum without entrapped mesenteric fat. This absence of mesentery entrapped into the intussuscepted bowel, along with the intact vascular supply (demonstrated by Doppler examination), might have resulted in minimum adhesion formation, which in turn might have contributed to spontaneous reduction in the present case series.
The median intussusception length in the current case series was 36.8 mm (range 26 to 46 mm). The authors consider this to be a relatively short intussusception, although no relative data are available for surgically treated dogs that can be used to confirm this conclusion. However, such a conclusion is consistent with the situation in children, for whom 86% of spontaneously reduced intestinal intussusceptions were <50 mm in length. The short length of the intussuscepted bowel probably predisposes to spontaneous reduction.10
The exact locations of the intussusceptions reported in the current study were not documented ultrasonographically but were most likely enteroenteric in nature. In one retrospective study, dogs with enterocolic intussusceptions appeared to be more at risk of developing adhesions than those with enteroenteric intussusceptions.1
Enteroplication has been reported to decrease the recurrence rate of intussusception in dogs, but it can be associated with serious complications.2,4,12 In the current case series, enteroplication was not performed during initial abdominal exploration, and two of five dogs developed recurrent intussusceptions. The authors conclude that abdominal exploration and enteroplication should be performed in all dogs having spontaneously reduced intussusceptions in order to decrease the risk of recurrence and associated complications.
Induction of anesthesia may contribute to spontaneous reduction, because it facilitates manual reduction in the operating room and increases the success rate of a second attempt at hydrostatic reduction.17,18 Moreover, some authors have recommended analgesic premedication to improve the rate of successful reduction during enema examinations.19 General anesthesia and analgesic premedication might have contributed to the spontaneous reduction observed in the current case series. Perioperative opioids have also been suggested to be associated with fewer recurrences of intussusceptions after initial correction.4 However, two of five intussusceptions in the present study recurred despite postoperative opioid administration.
The presence of blood flow within the intussusception reflects absence of vascular collapse in the intussuscepted bowel, which is usually associated with intussusceptions that are manually reducible.13 The presence of blood flow in most of the cases in this current study may reflect the presence of a loose intussusception that was predisposed to spontaneous reduction.
Many intra-abdominal conditions (e.g., normal intestine, enteritis associated with an intestinal foreign body, postpartum involution of the uterus) may appear as targetlike masses that could be misdiagnosed as intestinal intussusception. 20 The completeness of the periphery and the overall ring width of >8 mm observed in the present case series strongly support the accuracy of the ultrasonographic diagnosis of intestinal intussusception, suggesting that there were no misdiagnoses.20 In all five cases, accuracy of the diagnosis was also supported by the presence of a palpable abdominal mass, which was ultrasonographically confirmed as a target-like structure with a minimal diameter of 18 mm.
Conclusion
This study showed that spontaneous reduction of intestinal intussusception associated with acute enteritis or gastroenteritis can occur in young dogs. The authors, therefore, recommend ultrasonographic reexamination of the abdomen after induction of general anesthesia but before surgical treatment, to exclude spontaneous reduction of the intussusception. To prevent recurrence and associated complications, abdominal exploration and enteroplication should be performed in animals with persistent intussusception.
Apogge 800 ATL; Advanced Technology Labs Inc., Bothell, WA 98041
Calmivet; Vetoquinol, Lure Cedex, France
Butomidor; Richter Pharma AG, Wels, Austria
Diprivan 1%; Astrazeneca UK Ltd, Macclesfield, Cheshire, United Kingdom
Forenium; Abbott Laboratories LtD, Qweenborough, Kent, United Kingdom
Fentanyl; Janssen Pharmaceutica NV, Beerse, Belgium
Rimadyl; Pfizer Inc., Grampian Pharmaceuticals LtD., London, United Kingdom
Pentothal; Abbott SpA., Campoverde di Aprila, Italy
Citation: Journal of the American Animal Hospital Association 44, 1; 10.5326/0440041
Citation: Journal of the American Animal Hospital Association 44, 1; 10.5326/0440041
Citation: Journal of the American Animal Hospital Association 44, 1; 10.5326/0440041
Citation: Journal of the American Animal Hospital Association 44, 1; 10.5326/0440041
Citation: Journal of the American Animal Hospital Association 44, 1; 10.5326/0440041
Transverse (A) and longitudinal (B) ultrasonographic section of the intestine in a 3-month-old, male German shepherd dog (case no. 1). In transverse section (A), a target-like mass (arrows) consists of multiple hyperechoic and hypoechoic concentric rings surrounding a hyperechoic linear center. In longitudinal section (B), multiple hyperechoic and hypoechoic parallel lines form a trident-like configuration. The above ultrasonographic features are typical of intestinal intussusception.
Transverse color Doppler ultrasonographic image of the intestine in a 3-month-old, female German shepherd dog (case no. 2), showing a target-like mass (arrows) characteristic of intestinal intussusception. Color Doppler revealed blood flow in the entrapped mesenteric vessels (mv).
Longitudinal ultrasonographic section of the intestine in a 5-month-old, female mixed-breed dog (case no. 3). The appearance of multiple hyperechoic and hypoechoic parallel lines is consistent with the presence of intestinal intussusception (arrows). This appearance results from the juxtaposition of the respective walls of the intussuscipiens, the inner and outer intussusceptum, and the different echogenicity of the layers of the intestinal wall.
Longitudinal ultrasonographic section of the intestine in an 8-month-old, male mixed-breed dog (case no. 4). The respective walls of the intussuscipiens (a) are juxtaposed with the outer (b) and inner (c) intussusceptum, creating a trident-like configuration typical of the intestinal intussusception (L=intestinal lumen).
Transverse ultrasonographic image of the intestine in a 3-month-old, male mixed-breed dog (case no. 5). A target-like mass (arrows) consisting of multiple hyperechoic and hypoechoic concentric rings around a section of small intestine represents the inner intussusceptum (i).
