History
A 7-year-old 32.7-kg (71.9-lb) spayed female Labrador Retriever was referred because of a 7-day history of lethargy, 12-hour history of increased respiratory effort, and 1 episode of vomiting (bile and partially digested food) on the day of referral. The referring veterinarian reported that the dog had no history of dietary indiscretion. On initial referral examination, the dog was quiet, alert, and responsive. The only clinically abnormal findings were absence of breath sounds in the left caudal quadrant of the lung field and mild lameness in the left hind limb. The owners reported that the dog's lameness may have been from an unknown trauma a few years earlier, the exact date of which they could not remember. Results of a CBC and serum biochemical analyses were within reference limits. Thoracic and cranial abdominal radiographic images (Figure 1) obtained and provided by the referring veterinarian were reviewed.
Right lateral thoracic (A) and ventrodorsal caudal thoracic and cranial abdominal (B) radiographic images of a 7-year-old 32.7-kg (71.9-lb) spayed female Labrador Retriever evaluated because of a 7-day history of lethargy, 12-hour history of increased respiratory effort, and 1 episode of vomiting (on the day of referral). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Right lateral thoracic (A) and ventrodorsal caudal thoracic and cranial abdominal (B) radiographic images of a 7-year-old 32.7-kg (71.9-lb) spayed female Labrador Retriever evaluated because of a 7-day history of lethargy, 12-hour history of increased respiratory effort, and 1 episode of vomiting (on the day of referral). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Right lateral thoracic (A) and ventrodorsal caudal thoracic and cranial abdominal (B) radiographic images of a 7-year-old 32.7-kg (71.9-lb) spayed female Labrador Retriever evaluated because of a 7-day history of lethargy, 12-hour history of increased respiratory effort, and 1 episode of vomiting (on the day of referral). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Formulate differential diagnoses and treatment strategies from the history, clinical findings, and Figure 1—then turn the page→
Diagnostic Imaging Findings and Interpretation
Radiography revealed a large gas-filled structure with a thin soft tissue opaque rim in the caudodorsal aspect of the left hemithorax (Figure 2). The margins of the lesion appeared smooth, except for an undulant medial margin. The gas-filled pyloric antrum and body of the stomach were evident in the cranial aspect of the abdomen. Given these findings combined with the dog's nonspecific clinical signs, the differential diagnoses for the abnormal gas-filled structure in the thorax included a large pulmonary bulla or bleb, paraesophageal hernia, focal left diaphragmatic hernia, cavitated soft tissue mass or abscess, or unilateral diaphragmatic paralysis, eventration, or palsy. Incidental radiographic findings included a soft tissue band superimposed over the dorsal aspect of the tracheal lumen in the caudal cervical region that possibly represented the esophagus, hypaxial musculature, or a redundant tracheal membrane.
Same images as in Figure 1. A large gas-filled structure with a thin soft tissue opaque rim (white arrows; A and B) is present in the caudodorsal aspect of the left hemithorax, with partial border effacement of the diaphragm (black arrows; B). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Same images as in Figure 1. A large gas-filled structure with a thin soft tissue opaque rim (white arrows; A and B) is present in the caudodorsal aspect of the left hemithorax, with partial border effacement of the diaphragm (black arrows; B). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Same images as in Figure 1. A large gas-filled structure with a thin soft tissue opaque rim (white arrows; A and B) is present in the caudodorsal aspect of the left hemithorax, with partial border effacement of the diaphragm (black arrows; B). The images are published with permission by Parade Street Veterinary Hospital, the copyright holder with all rights reserved. Anyone wishing to reproduce the images is directed to contact Parade Street Veterinary Hospital, 92 Parade Street, Yarmouth, Nova Scotia B5A 3B4 Canada.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Thoracic CT without contrast medium was performed with a 16-slice helical multidetector CT scanner with a 1-mm slice thickness (Figure 3). There was cranial displacement of the fundus and a portion of the body of the stomach through a small rent in the left dorsal region of the diaphragm. The herniated portion of the stomach was distended with fluid and gas, and a horizontal (meniscal) fluid line was evident. The esophagus appeared to have entered the abdomen in an anatomically normal position through the esophageal hiatus but then diverted leftward and cranially to the gastroesophageal junction. Gas appeared evident in the pyloric antrum of the stomach, which had not herniated into the thoracic cavity. On the basis of CT findings, diaphragmatic hernia was considered the most likely diagnosis.
Transverse (A), sagittal (B), and dorsal (C) plane thoracic CT images of the dog in Figures 1 and 2. The fundus and part of the body of the stomach (white arrows; A through C) are cranially displaced into the caudodorsal aspect of the left hemithorax through a narrow defect in the diaphragm (black arrow; B). This herniated portion of the stomach is distended with gas and fluid, and a clear horizontal fluid line (asterisk; A and B) is evident. Gas in the pyloric antrum of the stomach (lightning bolt; B and C) is evident caudal to the diaphragm. The diaphragmatic crus (arrowhead; C) is displaced caudally. Images are displayed in a soft tissue window (1-mm slice thickness; window width, 320 HU; window level, 40 HU). A—The image is obtained at the level of T9, and the dog's right is toward the left of the image. B—The image is obtained left of sagittal midline at the level of the right kidney, and the dog's head is toward the left of the image. C—The image is obtained at the level dorsal to the aorta, and the dog's right is to the left of the image.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Transverse (A), sagittal (B), and dorsal (C) plane thoracic CT images of the dog in Figures 1 and 2. The fundus and part of the body of the stomach (white arrows; A through C) are cranially displaced into the caudodorsal aspect of the left hemithorax through a narrow defect in the diaphragm (black arrow; B). This herniated portion of the stomach is distended with gas and fluid, and a clear horizontal fluid line (asterisk; A and B) is evident. Gas in the pyloric antrum of the stomach (lightning bolt; B and C) is evident caudal to the diaphragm. The diaphragmatic crus (arrowhead; C) is displaced caudally. Images are displayed in a soft tissue window (1-mm slice thickness; window width, 320 HU; window level, 40 HU). A—The image is obtained at the level of T9, and the dog's right is toward the left of the image. B—The image is obtained left of sagittal midline at the level of the right kidney, and the dog's head is toward the left of the image. C—The image is obtained at the level dorsal to the aorta, and the dog's right is to the left of the image.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Transverse (A), sagittal (B), and dorsal (C) plane thoracic CT images of the dog in Figures 1 and 2. The fundus and part of the body of the stomach (white arrows; A through C) are cranially displaced into the caudodorsal aspect of the left hemithorax through a narrow defect in the diaphragm (black arrow; B). This herniated portion of the stomach is distended with gas and fluid, and a clear horizontal fluid line (asterisk; A and B) is evident. Gas in the pyloric antrum of the stomach (lightning bolt; B and C) is evident caudal to the diaphragm. The diaphragmatic crus (arrowhead; C) is displaced caudally. Images are displayed in a soft tissue window (1-mm slice thickness; window width, 320 HU; window level, 40 HU). A—The image is obtained at the level of T9, and the dog's right is toward the left of the image. B—The image is obtained left of sagittal midline at the level of the right kidney, and the dog's head is toward the left of the image. C—The image is obtained at the level dorsal to the aorta, and the dog's right is to the left of the image.
Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.479
Treatment and Outcome
The dog underwent exploratory laparotomy, which confirmed diaphragmatic hernia and revealed a 4-cm fibrotic rent in the same left dorsal aspect of the diaphragm indicated on CT. An incision to extend the fibrotic rent allowed reduction of the hernia, after which the stomach appeared to have only mild to moderate venous congestion. A thoracic drain was placed, and the diaphragmatic defect was closed. In addition, a nasogastric tube was placed to prevent postoperative gastric distention and to monitor for ileus. The dog recovered without complications, and the nasogastric tube and thoracic drain were removed 2 days after surgery. The dog was discharged 3 days after surgery.
Comments
The most common cause of diaphragmatic hernia in dogs and cats is thought to be trauma.1,2 The abdominal organs that herniate through a rent in the diaphragm depend on the location and size of the rent,1 and single-organ herniation is unusual.5 Organs commonly involved in diaphragmatic hernia include liver, spleen, omentum, intestines, and stomach,1,2,5 and typically, omentum is found in combination with any other organ herniated through the diaphragmatic rent. Considering that there was no recent trauma in the history of the dog of the present report, we suspected that the hernia was a long-term condition and that the inciting trauma could have been the same unknown trauma to which the owners attributed the dog's lameness. A chronic traumatic diaphragmatic hernia arises from a rent or tear in the diaphragm and usually is not associated with the esophageal hiatus. In the dog of the present report, we suspected that a small portion of the fundus of the stomach had herniated through the rent with or soon after the traumatic event. The small portion of herniated stomach may have slowly filled with air over time, resulting in progressively more stomach entering the thoracic cavity. The slow progression of more stomach being incorporated in the hernia could have explained the relative lack of clinical signs and the preservation of the stomach tissue through such a small rent.
Chronic hernias can be difficult to diagnose owing to nonspecific clinical signs (eg, dyspnea, tachypnea, weight loss, vomiting, and anorexia). Complications of a chronic diaphragmatic hernia include strangulation of abdominal organs (eg, stomach, liver, small intestines, omentum, pancreas, and spleen), pleural effusion, lung lobe torsions, and adhesions between herniated organs and structures in the thoracic cavity.2
From the radiographic images provided by the referral veterinarian, it was difficult to determine on which side of the diaphragm the air-filled structure was located because the stomach wall was not radiographically distinguishable from the diaphragm. In addition, no pleural effusion or fluid-filled structure was noticed in the thoracic cavity on radiographs; yet, fluid was evident in the herniated portion of the stomach on CT images. It was possible that fluid in the herniated portion of the stomach was not radiographically evident because a lateral horizontal beam was not used to obtain the images. Because the lesion radiographically appeared to have been filled with gas and the dog recently developed signs of increased respiratory effort, the primary differential diagnosis before CT was a large pulmonary bulla, which can occur after a traumatic episode or could be congenital in origin.3 However, pulmonary bulla as a diagnosis was still questionable because of the subjectively thick soft tissue borders of the dog's lesion evident on the radiographic images. In addition, traumatic pulmonary bullae occur more suddenly after trauma and are often much smaller than the lesion identified radiographically in the dog of the present report. Further, pulmonary bullae are commonly diagnosed after the occurrence of spontaneous pneumothorax,4 which was not documented in the history of this dog.
We also suspected paraesophageal hernia (type II hiatal hernia) in the dog of the present report. Contrast radiography or fluoroscopy may have been able to show the location of the esophagus as it crossed the diaphragm; however, if a hiatal hernia was present, the contrast agent may not have been able to delineate the herniated portion of the stomach.
A study2 of 34 dogs and 16 cats with chronic diaphragmatic hernias shows that 14 of 48 (29%) animals that underwent thoracic radiography had diaphragmatic hernias that could not be diagnosed on the basis of radiographic findings. Therefore, it is important that further diagnostic imaging (eg, ultrasonography or CT) be performed when nonspecific radiographic abnormalities are noted in the thoracic cavity. In the dog of the present report, ultrasonography was not performed because we suspected a large air-filled structure, which would have obscured imaging of tissues deeper to the structure.
With CT, however, we were able to diagnose diaphragmatic hernia, identify the organs involved, locate the diaphragmatic defect, and better plan for surgery. Findings in the dog of the present report underscored the usefulness and importance of CT in further evaluating patients with nonspecific radiographic abnormalities so that more definitive diagnosis, prognosis, and treatment (eg, medical vs surgical and thoracotomy vs laparotomy) can be provided.
References
1. Hunt GB, Johnson KA. Diaphragmatic hernia. In: Johnson KA, Tobias KM, eds. Veterinary surgery small animal. 2nd ed. St Louis: Elsevier Saunders, 2018;1592–1603.
2. Minihan AC, Berg JB, Evans KL. Chronic diaphragmatic hernia in 34 dogs and 16 cats. J Am Anim Hosp Assoc 2004;40:51–63.
3. Stogdale L, O'Connor CD, Williams MC, et al. Recurrent pneumothorax associated with a pulmonary emphysematous bulla in a dog: surgical correction and proposed pathogenesis. Can Vet J 1982;23:281–287.
4. Lipscomb VJ, Hardie RJ, Dubielzig RR. Spontaneous pneumothorax caused by pulmonary blebs and bullae in 12 dogs. J Am Anim Hosp Assoc 2003;39:435–445.
5. Hyun C. Radiographic diagnosis of diaphragmatic hernia: review of 60 cases in dogs and cats. J Vet Sci 2004;5:157–162.
