What Is Your Diagnosis?

Audrey C. Billhymer Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608.

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Federico R. Vilaplana Grosso Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608.

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Stanley E. Kim Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608.

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History

A 4-year-old 25-kg (55-lb) spayed female Labrador Retriever was evaluated because of a sudden onset of vomiting, abdominal distension, anorexia, and signs of abdominal pain. Past pertinent medical history included a prophylactic gastropexy performed approximately 3 years earlier when the dog was spayed.

On physical examination, the dog was lethargic, tachycardic (heart rate, 152 beats/min; reference range, 80 to 120 beats/min), and dehydrated (approx 6%) and had tacky mucous membranes. Abdominal palpation elicited signs of pain, and the abdomen felt tense. Results of serum biochemical and blood gas analyses were within reference limits. Abdominal radiography was performed (Figure 1).

Figure 1—
Figure 1—

Left lateral cranial (A) and caudal (B) and ventrodorsal cranial (C) and caudal (D) abdominal radiographic images of a 4-year-old 25-kg (55-lb) spayed female Labrador Retriever evaluated because of a sudden onset of vomiting, abdominal distension, anorexia, and signs of abdominal pain.

Citation: Journal of the American Veterinary Medical Association 257, 10; 10.2460/javma.2020.257.10.1007

Formulate differential diagnoses and treatment strategies from the history, clinical findings, and Figure 1—then turn the page

Diagnostic Imaging Findings and Interpretation

Radiographic findings indicated that the transverse and ascending colon were severely distended with gas and abnormally positioned, with cranial displacement to the diaphragmatic margin and superimposition over the margins of the pylorus and gastric silhouette on all projections (Figure 2). The superimposition hindered clear identification of the pylorus. On the left lateral radiographic projections, the transverse and ascending colon had a C shape, appeared compartmentalized, and contained a moderate amount of granular, soft tissue opaque material with gas lucencies, consistent with feces. The descending colon was faintly visible and contained a small amount of granular opaque material with gas lucencies, consistent with feces. There was a focal area of mildly decreased serosal detail caudoventral to the distended ascending and transverse colon. A focal segment of presumed small intestine was also moderately gas distended (approx 2.5 times the height of L5); however, the remainder of the small intestine appeared radiographically normal and had uniform distribution. The stomach appeared to have been in a radiographically normal position and contained a small amount of gas. The remaining intra-abdominal structures appeared radiographically normal.

Figure 2—
Figure 2—

Same radiographic images as in Figure 1. The transverse and ascending colon (asterisks) are severely distended with gas. The colon is superimposed over the gastric silhouette (S) in all projections. The descending colon cannot be outlined clearly. A focal segment of presumed small intestine is moderately distended with gas (I).

Citation: Journal of the American Veterinary Medical Association 257, 10; 10.2460/javma.2020.257.10.1007

Given these findings, a colonic torsion was suspected, and for further evaluation and confirmation, pneumocolonography was performed with rectal administration of room air (2 mL/kg [0.9 mL/lb]) through a red rubber catheter (Figure 3). The previously described abnormal findings for the transverse and ascending colon were unchanged. However, with pneumocolonography, the descending colon became clearly evident radiographically, with moderate diffuse gas distension. In addition, a focal discontinuation between the descending and transverse colon was observed, with the cranial aspect of the descending colon tapered. The ileum was moderately gas distended, consistent with redistribution of colonic gas related to pneumocolonography. The previously described focal distension of a presumed segment of small intestine remained unchanged, and there was no clear connection established between it and the gas-filled ileum.

Figure 3—
Figure 3—

Left lateral (A) and ventrodorsal cranial (B) and caudal (C) abdominal pneumocolonographic images of the dog in Figures 1 and 2. As in the earlier radiographic images, the transverse and ascending colon (asterisks) are distended with gas, cranially displaced, and superimposed over the gastric silhouette (S), and a focal segment of suspected small intestine (I) is moderately gas distended. The ileum (cross) is gas filled, and the descending colon is clearly gas distended (arrowheads) and cranially tapers abruptly (arrow). The silhouette of a red rubber catheter used for pneumocolonography is also visible within the lumen of the descending colon.

Citation: Journal of the American Veterinary Medical Association 257, 10; 10.2460/javma.2020.257.10.1007

On the basis of clinical and radiographic findings combined with the dog's history of gastropexy, the prioritized differential diagnoses were colonic entrapment at the gastropexy site, colonic torsion, or both. The decreased serosal detail identified could have represented focal peritonitis, peritoneal effusion, or artifact (secondary to organ crowding). The focal gas distension in a presumed small intestinal loop could have been gas in the cecum or segmental distension of the small intestine suggestive of mechanical obstruction.

Treatment and Outcome

In preparation for exploratory laparotomy, the dog received lactated Ringer solution (20 mL/kg [9.1 mg/lb], IV as a bolus, followed by 120 mL/kg/d [54.5 mL/lb/d]), and the dog's signs of abdominal pain and nausea were initially managed with 1 dose each of methadone (0.2 mg/kg [0.1 mg/lb], IV) and maropitant (1 mg/kg [0.5 mg/lb], IV).

An exploratory laparotomy was performed with a standard ventral midline approach. The ascending and transverse colon were confirmed to have been entrapped cranially and dorsally at the healed gastropexy site (Figure 4). Colonic torsion was not present. The entrapment was manually reduced, with the colon repositioned in its normal anatomic location. A left-sided colopexy was performed at the midlevel of the abdominal wall and the distal portion of the transverse colon. A small amount of abdominal fluid was identified at surgery but was not sampled. There was no evidence of small intestinal mechanical obstruction. The dog recovered without any perioperative or postoperative complications.

Figure 4—
Figure 4—

Intraoperative image of the dog described in the previous figures. A gas-distended segment of colon (asterisk) is entrapped dorsal and cranial to the healed right-sided gastropexy site (pound sign). The dog is in dorsal recumbency, and its head is toward the upper right corner of the image.

Citation: Journal of the American Veterinary Medical Association 257, 10; 10.2460/javma.2020.257.10.1007

Comments

Findings in the dog of the present report were of a rarely reported condition of colon entrapment at the level of a healed gastropexy site, with secondary severe colonic distension. Colonic torsion, volvulus, or both is rare and most often reported in middle-aged, male, large-breed dogs.1–4 Previous studies2–4 show that the presence of a gastropexy may predispose dogs to the development of these conditions because of colonic entrapment at the level of the gastropexy site.2–4 Colonic entrapment has also been described secondary to rupture of the duodenocolic ligament or the presence of adhesions from prior abdominal surgery.3 Colonic torsion or volvulus, alone or in combination, is a life-threatening condition characterized by complete or partial obstruction of the colonic lumen and secondary vascular compromise, leading to ischemia and necrosis of the intestines and ultimately resulting in sepsis and potentially death.2,3 In the dog of the present report, diagnosis was facilitated by performing pneumocolonography, whereas previously, administration of a barium enema has been reported to aid in the diagnosis of colonic torsion through visualization of a torsion sign and abrupt cessation of contrast medium filling of the colon at the level of torsion.2

Similar to previous reports2,3 of colonic entrapment at the level of a gastropexy site, the gastropexy site itself in the dog of the present report appeared clinically normal on exploratory laparotomy. Also, in the dog of the present report, radiographic findings of the transverse and ascending colon superimposed with the stomach combined with segmental colonic gas distension suggested colonic entrapment at the level of the gastropexy site. Additionally, the pneumocolonographic finding of a focal discontinuation of luminal gas at the level of the descending and transverse colon was compatible with colonic volvulus.2

Following reduction of the colon, a left-sided colopexy5 was performed to decrease the risk of recurrence of colonic displacement in the dog of the present report. Alternatively, gastrocolopexy of the transverse colon to the greater curvature of the stomach has also been described.4

Aided by pneumocolonography, radiographic diagnosis of colonic entrapment allowed for prompt surgical intervention in the dog of the present report. Although colonic entrapment at a gastropexy site is rare, it should be considered a differential diagnosis for sudden signs of abdominal pain and severe colonic gas distension in dogs that have had gastropexy.

References

  • 1. Plavec T, Rupp S, Kessler M. Colonic or ileocecocolic volvulus in 13 dogs (2005–2016). Vet Surg 2017;46:851859.

  • 2. Gremillion CL, Savage M, Cohen EB. Radiographic findings and clinical factors in dogs with surgically confirmed or presumed colonic torsion. Vet Radiol Ultrasound 2018;59:272278.

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  • 3. Gagnon D, Brisson B. Predisposing factors for colonic torsion/volvulus in dogs: a retrospective study of six cases (1992–2010). J Am Anim Hosp Assoc 2013;49:169174.

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  • 4. Bentley AM, O'Toole TE, Kowaleski MP, et al. Volvulus of the colon in four dogs. J Am Vet Med Assoc 2005;227:253256.

  • 5. Holt DE, Brockman D. Large intestine. In: Slatter DH, ed. Textbook of small animal surgery. Vol 1. 3rd ed. Philadelphia: Saunders, 2003;670671, 678.

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