History
A 9-year-old 26-kg (57-lb) spayed female mixed-breed dog was admitted to the University of Florida Veterinary Medical Center for evaluation of anorexia, signs of abdominal discomfort, and dyspnea. The dog had a history of periodic vomiting of 6 weeks' duration that increased in frequency along with the onset of diarrhea and tachypnea. The dog was brought to a veterinarian and received SC administration of lactated Ringer solution and maropitant. The dog was sent home to be treated with metronidazole and sucralfate. The vomiting and diarrhea subsided over the next 24 hours; however, the clinical signs of anorexia, abdominal pain, and straining to defecate developed.
On hospital admission at the University of Florida, the dog's physical examination findings included dull mentation and tacky gums with a normal capillary refill time; the dog was estimated to be 6% dehydrated. The dog's body temperature was 38.7°C (101.7°F), and the heart rate was 140 beats/min. The dog was panting and dyspneic with increased lung sounds auscultated bilaterally. Abdominal tympany was noted in the cranial portion of the abdomen. Doppler ultrasonographic systolic blood pressure measurement was 130 mm Hg (reference range, 90 to 160 mm Hg). Venous blood gas analysis revealed a pH of 7.48 (reference range, 7.33 to 7.45), partial pressure of carbon dioxide of 36.3 mm Hg (reference range, 35 to 40 mm Hg), and blood lactate concentration of 4.7 mmol/L (reference range, 0.4 to 1.5 mmol/L). Abdominal and thoracic radiography was performed (Figure 1).
Right lateral (A) radiographic view of the abdomen and right lateral (B) and ventrodorsal (C) radiographic views of the thorax of a 9-year-old 26-kg (57-lb) spayed female mixed-breed dog evaluated because of anorexia, signs of abdominal discomfort, and dyspnea.
Citation: Journal of the American Veterinary Medical Association 253, 1; 10.2460/javma.253.1.35
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Radiographic Findings and Interpretation
The ventral aspect of the diaphragmatic margin is ill-defined on all radiographic images (Figure 2). On the radiographic projection of the abdomen, the stomach is moderately filled with gas, but is in an anatomically correct position. A gas-filled structure is present in the caudodorsal aspect of the thorax. The thorax also contains a heterogeneous soft tissue opacity ventrally. Multiple gas-filled tubular structures are seen superimposed over the larger gas-filled structure. A gas-filled tubular structure is evident cranial to the liver. The small intestines are not seen in the abdominal cavity. The rectum and descending colon contain a small amount of air. A smoothly marginated and lobular soft tissue opaque mass, measuring 16 × 13 cm, is in the midabdomen; multiple, small, mineral opacities are superimposed over the lobular mass with the mass displacing the spleen caudally.
Same radiographic images as in Figure 1. Notice the loss of the diaphragmatic margin in all images. The stomach is distended with gas but is in an anatomically correct position (arrows). A large, folded, tubular, gas-dilated structure is evident cranial to the stomach (double S symbols). Several smaller gas-filled loops are also seen in the right hemithorax (asterisks). The small intestines are not seen in the abdominal cavity. The descending colon and rectum (double dagger) are evident, and a large lobular soft tissue opacity mass is seen in the midabdomen (daggers).
Citation: Journal of the American Veterinary Medical Association 253, 1; 10.2460/javma.253.1.35
On the radiographic projections of the thorax, gas-filled tubular structures are seen in the ventral aspect of the right hemithorax (Figure 2). Additionally, within the caudodorsal aspect of the right hemithorax, there is a large, segmented, gas-dilated, tubular structure with compartmentalization that measures 15 cm in diameter; the tubular structure contains ventrally distributed heterogeneous soft tissue opaque material. An increase in soft tissue opacity is appreciable in the pleural space with border effacement of the cardiac silhouette with surrounding structures. The right middle and right caudal lung lobes are retracted from the thoracic wall between which there is a soft tissue opacity. A lobar sign is present just cranial to the tubular structure in the right mid portion of the thorax; there is increased pulmonary opacity, particularly right sided, with border effacement of the pulmonary vasculature. A slight left mediastinal shift is present and the accessory lung lobe is not visible.
The presence of intestinal contents within the pleural cavity is diagnostic for a diaphragmatic hernia, most likely right sided because of the asymmetric distribution of contents and loss of right diaphragmatic detail on the ventrodorsal projection of the thorax. The gas dilated-tubular structure measuring 15 cm in diameter is most likely the colon because of the normal anatomic position of the stomach and the degree of dilation. Such dilation of the colon may indicate entrapment and strangulation through the diaphragmatic rent or a torsion or volvulus of the colon. The other large lobular soft tissue opacity mass located in the midabdomen is for similar reasons also expected to be the colon, potentially the ascending colon with associated gastrointestinal contents. Although this lobular mass could be any distended loop of intestine or an incidental abdominal mass, its degree of dilation, angulation toward the suspect herniated gas-filled colon, and the expected obstruction caused by herniation or a volvulus suggest colonic origin. The abdominal contents within the thorax have displaced the lung lobes resulting in pulmonary atelectasis. Congestion of intestinal segments, tearing of the diaphragm, or both are likely contributing to the pleural effusion.
Treatment and Outcome
After fluid resuscitation, surgery was pursued to address the diaphragmatic hernia and assess the abdomen. A 4-cm-long defect was found in the diaphragm near the right crus. Abdominal contents, primarily intestines and pancreas, were retrieved from the thoracic cavity including a 270° clockwise colonic volvulus, which was derotated and retracted through the epiploic foramen. Postoperative recovery included 8 days of critical care hospitalization prior to hospital discharge. The dog survived another 2 years before dying of an unrelated cause.
Comments
Diaphragmatic hernias in dogs are typically associated with trauma or are congenitally preexisting. Traumatic herniation is reported to occur when blunt force trauma increases intra-abdominal pressure while the glottis is open, resulting in acute decompression of the lungs, destabilization of counter pressures, and thus diaphragmatic tearing.1 Radiographic imaging is a helpful step in the diagnosis of this disease process. Common radiographic findings include a poorly defined diaphragmatic margin and a lack of abdominal contents within the peritoneal cavity.1–3 The intrathoracic cavity is often increased in opacity because of the presence of abdominal contents silhouetting with the thoracic structures; tubular potentially gas-filled structures or displaced organ margins may be identified in the thorax along with a mediastinal shift.1–3 The stomach, liver, and small intestines are reportedly the most common organs to herniate with occurrence rate potentially relating to the location of the hernia.3,4 The colon has been reported to herniate into the pericardial sac in dogs and cats with congenital peritoneopericardial diaphragmatic herniation, but overall, to the authors' knowledge, it appears pleural cavity colonic herniation is less common. The dog of the present report was found to have most of the small intestines as well as the colon herniated into the pleural space along with intrathoracic colonic volvulus. It is hypothesized that the colonic volvulus occurred in the period immediately prior to hospital admission.
To the authors' knowledge, colonic torsion and volvulus in small animals have previously only been described in the abdominal cavity.5–7 Torsion is defined as a rotation along the long axis of the colon, whereas volvulus is rotation around the root of the mesentery.6,7 Radiographic imaging can be helpful in identifying suspected colonic volvulus even when displaced into the thorax as seen in the dog of the present report. Typically, radiographic signs include marked to severe gas distension of the colon along with increased gas opacity throughout most of the intestines orad to the volvulus.7 The dog of the present report had a substantially dilated tubular segment noted within the thorax, for which the degree of dilation was highly suggestive of colonic origin. Heterogeneous opacity within the segment of affected intestine likely represented fecal material, further supporting colonic origin. Surgery confirmed colonic herniation and volvulus with its associated dilation. Preventative colonopexy has been recommended after colonic torsion or volvulus but was not performed in the dog of the present report, as the concern for viability of the colon was too high.5,7 Small intestinal volvulus has been associated with a high mortality rate; however, large intestinal volvulus identified by radiography and addressed promptly with surgery may have a good prognosis.5 For the dog of the present report, radiographic features previously reported for abdominal colonic volvulus proved valuable in identifying the surgically emergent condition in the presence of the coexisting diaphragmatic herniation.
References
1. Worth AJ, Machon RG. Traumatic diaphragmatic herniation: pathophysiology and management. Compend Contin Educ Pract Vet 2005;27:178–190.
2. Sullivan M, Lee R. Radiological features of 80 cases of diaphragmatic rupture. J Small Anim Pract 1989;30:561–566.
3. Hyun C. Radiographic diagnosis of diaphragmatic hernia: review of 60 cases in dogs and cats. J Vet Sci 2004;5:157–162.
4. Banz AC, Gottfried SD. Peritoneopericardial diaphragmatic hernia: a retrospective study of 31 cats and eight dogs. J Am Anim Hosp Assoc 2010;46:398–404.
5. Davis E, Townsend FI, Bennett JW, et al. Comparison of surgically treated large versus small intestinal volvulus (2009–2014). J Am Anim Hosp Assoc 2016;52:227–233.
6. Halfacree ZJ, Beck AL, Lee KCL, et al. Torsion and volvulus of the transverse and descending colon in a German Shepherd Dog. J Small Anim Pract 2006;47:468–470.
7. Bentley AM, O'Toole TE, Kowaleski MP, et al. Volvulus of the colon in four dogs. J Am Vet Med Assoc 2005;227:253–256.
