Chronic diaphragmatic hernia (CDH) in dogs and cats is most commonly caused by trauma, particularly motor vehicle accidents (1,19). The most frequent clinical signs are dyspnea and vomiting; however, many affected animals with CDH are asymptomatic or may be presented for nonspecific signs such as anorexia, lethargy, and weight loss (12). Various different abdominal structures including the liver, spleen, stomach, intestine, pancreas, have been reported to herniate into the thoracic cavity, according to the location of diaphragmatic rupture. In the case of a right sided hernia, the small intestine and liver are often found to be herniated (3). Dogs and cats with left sided rupture of diaphragm are likely to die due to respiratory difficulty, which can result from a herniated distended stomach.

Lung lobe torsion (LLT) is defined by a rotation of a lung lobe around its long axis, followed by displacement and twisting of the lobar bronchus and vessels at the hilus or bronchovascular pedicle, and can cause significant morbidity and mortality if not promptly corrected (16,18). The predominant clinical signs of LLT are lethargy, progressive dyspnea, coughing, anorexia (13). Physical examination may reveal pale mucous membranes, dull cardiopulmonary sounds, pyrexia, and cyanosis. Since LLT can result in airway obstruction and vascular compromise, it is considered as a life-threatening condition in dogs and cats (4).

This case report describes clinical findings, diagnostic imaging and surgical treatment for right middle LLT two-weeks after CDH repair in a dog.

A 5-year-old, 30 kg, intact male wild boar hunting Laika dog was referred to the Veterinary Medicine Teaching Hospital of Kangwon National University, South Korea with a history of trauma sustained while hunting 3 months previously, accompanied by gradual weight loss and exercise intolerance. On physical examination, the animal was panting, had a rectal temperature of 39.0°C and an elevated heart rate of 180 beats/min. Complete blood counts (CBC) showed a normal leukogram and hematocrit level. On serum biochemistry analysis, abnormalities were noted as follows; increased alkaline phosphatase to a level of 1,451 U/L (reference range, 20 to 150 U/L), increased alanine transferase to 276 U/L (reference range, 10 to 118 U/L), increased gamma-glutamyl transpeptidase to 10 U/L (reference range, 0 to 7 U/L).

Plain radiography revealed the protrusion of gas-filled small bowel loops into the thoracic cavity with descending duodenal displacement. Moreover, contrast radiographic examination using barium sulphate (RAYDIX SOLN^®, Dongindang Ltd., Korea) as a contrast agent confirmed the presence of a diaphragmatic hernia (Fig. 1E, F). Midline laparotomy revealed right displacement of the stomach and rounding of the liver edges with a distended gallbladder (Fig. 1C), in additionally showed to severe adhesion between the diaphragm and duodenum. Exploration of the thoracic cavity demonstrated collapse of the right medial lung lobe. Release of the adherent duodenum required the resection of a portion of the duodenum (Fig. 1H). The duodenum was sutured in a simple interrupted pattern following insertion of a 6 Fr feeding tube into the common bile duct to prevent biliary obstruction in major duodenal papilla. The lungs were mechanically ventilated to inflate the collapsed right middle lobe. Then, the defect in the diaphragm, located at the right dorsal aspect, was sutured using 1-0 nylon on a round needle (Fig. 1G). Prior to closure of the abdominal cavity, peritoneal lavage was performed. Two weeks following diaphragmatic herniorrhaphy, the dog was re-admitted with an acute onset of increased respiratory effort. Thoracic radiographs and CT showed increased soft tissue density in the right side of the thorax (Fig. 2A, B). The cardiac silhouette was obscured due to pleural effusion (Fig. 2C). Transverse chest CT on lung window showed consolidation of the right middle lung lobe with abnormal tapering of the bronchus (Fig. 2D). Based on these findings the dog was diagnosis right middle LLT.

Figure 1. Radiography and surgery of diaphragmatic hernia repair. (A) Lateral radiographs show herniation of abdominal organs into the thoracic cavity with gas filled intestinal loops (arrow) and absence of cardiac silhouette. (B) Ventrodorsal radiograph shows the cranial deviation of the abdominal contents mainly in the right hemithorax and absence of diaphragmatic line (dashed line). (C) Opened peritoneal cavity shows right displacement of stomach (asterisk) and rounded liver margins with distended gallbladder. (D) Intraoperative view shows herinated small intestion and distended diaphragm (asterisk) in right side peritoneal cavity. (E) Contrast lateral radiograph shows herniation of small intestine into the thoracic cavity (arrow). (F) Contrast ventrodorsal radiograph also confirmed displacement of small intestine containing barium contrast agent in the right hemithorax (arrow). (G) Reduction herinated intestine to peritonium and diaphragmtic herina ring (dashed line) dorsal part of hernial ring adherent to duodenum. (H) Duodenum rupture site during reduction herinated intestine to peritonium by duodenal diaphragm adhesion (arrow).

Figure 2. Radiography and computed tomography imaging. Ventrodorsal (A) right lateral (C), thoracic radiographs of the same dog 2 weeks after diaphragmatic hernia repair. (A) Soft tissue opacity mass revealed in right middle lung fields at the level of the fifth to ninth intercostal spaces (dashed line). (B) Consolidation of the right middle lung lobe is clearly seen (asterisk). (C) There is an increase in soft tissue opacity in the cardiac region (asterisk) with absence of the cardiac silhouette. Mild pleural effusion is also visible. (D) Transverse CT of the thorax with lung window of a dog with right middle lung lobe torsion. The bronchus directed to the right middle lung lobe has a conical shape (arrow) with abrupt ending. Right middle lung lobe is consolidated (asterisk).

Exploration of the right hemithorax confirmed torsion of right middle lung lobe. The lobe was dark red, enlarged, edematous (Fig. 3A). Right middle lung lobectomy was performed. Briefly, the consolidated lobe was gently exteriorized from the thoracic cavity without de-rotation, then a DST series thoracoabdominal stapler (TA3035L; Covidien, Mansfield, USA) was used at the bronchus level in torsed lobe (Fig. 3B). The dog recovered and discharged five days postoperatively. The patient recovered without any complications over a 6-month follow-up period.

Figure 3. Right middle lung lobectomy. (A) Thoracotomy at the right fourth to fifth intercostal spaces, showing a torsed, red colored right lung lobe (asterisk). (B) The torsed lobe was resected using a TA stapler. (C) Resected right middle lung lobe. (D) Histological evaluation of the pulmonary parenchyma, extensive hemorrhage (arrow) and necrosis associated with abundant amounts of fibrin and large numbers of scattered viable and degenerate neutrophils (arrowhead).

In this case, diaphragmatic hernia was assumed to be associated with the trauma that had occurred 3 months prior admission to the hospital. Thus the hernia was classified as CDH according to Minihan’s criteria (1,12). Diaphragmatic hernia has been reported to be associated with various thoracic consequences including lung lobe torsion (7,12). LLTs have been previously reported in dogs, especially large-breeds with a deep, narrow chest. They are often secondary to predisposing conditions such as pleural effusion, thoracic trauma, diaphragmatic hernia, or following surgery (19). The right middle lung lobe is the most common lobe affected because of its increased mobility associated with its long, narrow shape, short bronchovascular pedicle and lack of supportive pulmonary ligaments (8). Although Laika are deep-chested, large-breed dog, to the authors’ knowledge, LLT has not been previously reported in the literature for this breed.

The exact mechanism of LLT occurrence is still controversial. Any disease that results in pleural effusion or pneumothorax seems to increase the space surrounding the affected lobe and subsequently enhances the mobility of a lung lobe which is already prone to possible torsion (2,17). Additionally, the pressure caused by abdominal viscera protruding into the thorax and changes in intrathoracic pressure could play a role (7,15).

In our case, we assumed that the protrusion of the intestine into the thoracic cavity resulted in severe compression and atelectasis of the right middle lung lobe. The compression of the right middle lung lobe was simply detected during repair of the diaphragmatic hernia. We propose that the shrunken, collapsed lobe facilitated the mobility of the lobe and caused the right LLT.

Chronic pulmonary collapse may be resolved by gentle manual inflation of the lungs with a maximum inflation pressure of 10 to 20 or 30 cm H₂O, however nuintended barotrauma can induced as side effect (9). To avoid the occurrence of LLT after diaphragmatic hernia repair, careful manual inflation of the lungs prior to closure of the diaphragmatic defect may be beneficial. Repositioning the torsed lobe for treatment of LLT in humans has been reported, however later resection was required in most of these trials (5,6). The recommended method for prevention of LLT after diaphragmatic hernia is to perform surgical fixation of collapsed lobe to other lobes as performed in human medicine (20).

Lung lobectomy is still the treatment of choice for LLT (1). Importantly, the torsed lung lobe should be removed without de-rotation as this may lead to release of cytokines, toxins and oxygen radicals into the circulation (7). Surgical staplers have been described for lung lobectomy in dogs during open surgery by applying 3-4 rows of staples. In this case, we used 60 mm cartridges with 3.5 mm long staples to perform lung lobectomy (10,11). The overall survival in large breed dogs with LLT is reported in literature 87% with recurrence of torsion between 5 and 180 days after the original presentation in 11% of cases (1,14). After a diphragnatic hernia repair, there is no postoperative complications or recurrence were noticed in this dog during 6-months follow-up.

This study is a report of a rare case describe the occurrence of LLT in a dog after a CDH repair. It would be helpful in veterinary practice that repair of the diaphragmatic hernia as soon as it is diagnosed may be beneficial in avoiding adhesions of viscera with the diaphragm, and pressure on lung lobes that may lead to pulmonary collapse, atelectasis and subsequent torsion. Additionally, we suggest that the patient should be monitored for 2 weeks after diaphragmatic hernia repair with cage rest to avoid the occurrence of LLT.

None.

The authors have no conflicting interests.