Spontaneous Midlobar Lung Lobe Torsion in a 2-Year-Old Newfoundland

Lung lobe torsion in 15 dogs: Peripheral band sign on ultrasound

The diagnosis of lung lobe torsion in dogs is usually based on radiological, endoscopic, and CT features. Few ultrasonographic descriptions have been published. The purpose of this multicenter, retrospective, and prospective observational study was to investigate the presence of a hypoechoic area forming a pulmonary band or line at the periphery of the twisted lobe on ultrasonography and assess its significance by comparing it to CT and histological findings. Fifteen dogs with lung lobe torsion confirmed surgically or postmortem were included. All had received ultrasonography and CT examinations; 13 had additional histopathological examination performed. In 14 cases, thoracic ultrasonography revealed a peripheral hypoechoic band, overlying areas of scattered, hyperreflecting interfaces in the affected lobe. On CT, central emphysema was surrounded by a peripheral, soft tissue attenuation band, affecting the periphery in 14 cases. No band was observed in one case, in which the lobe was entirely consolidated. Histological examination yielded a comparable peripheral band, consisting of a thickened visceral pleura with or without hemorrhagic necrosis of the underlying pulmonary parenchyma. This peripheral band may be related to the specific fractal organization of airways and vessels, which plays an important role in lung perfusion and ventilation and makes the lung periphery more prone to ischemia. Our findings suggest that the presence of a peripheral hypoechoic band, associated with central emphysema in a noncollapsed lung lobe on ultrasonography, is suggestive of compromised blood supply and air flow, and lung lobe torsion should therefore be suspected.

Long-term survival after treatment of idiopathic lung lobe torsion in 80 cases

OBJECTIVE

To report outcomes of dogs treated for lung lobe torsion (LLT) and to determine prognostic factors for survival.

STUDY DESIGN

Retrospective multicenter study from four veterinary teaching hospitals.

ANIMALS

Dogs (n = 80) with LLT.

METHODS

Medical records were reviewed for clinical and histopathological findings. Long-term outcome was assessed with an owner questionnaire. Lung lobe torsion was classified as idiopathic or secondary on the basis of the etiology.

RESULTS

The most represented breeds were pugs (47.5%) and sighthounds (16.2%). The cause of the LLT was considered primary in 77%, secondary in 21%, and unknown in 2% of dogs. Postoperative complications were recorded in 14% of dogs. Overall, 95% of dogs survived to discharge, and median follow-up was 1095 days (range, 7-3809). Owners assessed outcomes and quality of life as excellent in 93% and 89% of dogs, respectively. Primary LLT was associated with a longer survival (median not reached in the study) compared with secondary LLT (921 days; range, 7-2073; P = .001).

CONCLUSION

Overall long-term survival after lung lobectomy for LLT was excellent. Primary LLT was associated with longer survival compared with secondary LLT. Long-term owner evaluation of clinical outcome for dogs undergoing lung lobectomy for LLT was considered excellent.

CLINICAL IMPACT

Dogs with primary LLT undergoing lung lobectomy have a longer survival time compared with dogs with secondary LLT and have an excellent postoperative outcome.

Contrast-enhanced ultrasonographic findings in three dogs with lung lobe torsion

Lung lobe torsion is rare but life-threatening condition in the dog. Thoracic radiographs and conventional ultrasonography cannot be conclusive for the diagnosis, and computed tomography is useful but is limited by cost and availability. This report describes the findings of contrast-enhanced ultrasonography in 3 dogs with lung lobe torsion. Contrast-enhanced ultrasonography showed the absence or reduction of pulmonary vascularization secondary to twisting of the lung lobe around its bronchovascular pedicle in all three dogs. Moreover, contrast-enhanced ultrasonography distinguished partial pulmonary atelectasis from a lung lobe torsion. These preliminary results suggest that contrast-enhanced ultrasonography can improve the accuracy of conventional ultrasonography for detection of pulmonary blood flow compromise in dogs with lung lobe torsion.

Usefulness of CT imaging for segmental lung lobe torsion without typical radiographic imaging in a Pomeranian

A 3-year-old, intact female Pomeranian presented with a 1-month history of coughing. Thoracic radiography showed focal infiltration of the left cranial lung lobe and widening of the cranial mediastinum. Subsequent computed tomography revealed torsion of the caudal segment of the left cranial lung lobe, which was confirmed by exploratory thoracotomy. There was no apparent underlying etiology for the condition. To the authors’ knowledge, this is the first report of lung lobe torsion in this breed and the first detailed CT imaging report for segmental lung lobe torsion.

RADIOGRAPHIC DIAGNOSIS OF LUNG LOBE TORSION

Clinical data, thoracic radiographs, ultrasonographic exams, and histopathologic reports in 13 dogs and two cats with confirmed lung lobe torsion were reviewed. Age of dogs ranged from 4 months to 11.5 years, (mean of 6.4 years) and several breeds of large and small dogs were represented. Right middle lobe torsion was predominant in large dogs (five of eight large breed dogs) and left cranial lobe torsion was more commonly seen in small dogs (three of five small-breed dogs). Two domestic short-hair cats, 10 and 14 years of age, had right cranial and right middle lobe torsion, respectively. Underlying thoracic disease was found in only five of 15 patients. On thoracic radiographs, increased lobar opacity and pleural effusion were found in all patients (100%). Small dispersed air bubbles were found within the affected lobe of 13 patients (87%). This pattern, which was the result of vesicular emphysema, was variably extensive, and became more evident on follow-up radiographs in five of six dogs. The lobar bronchi could be seen in only eight of 15 patients (54%), and appeared irregular, focally narrowed or blunted in six of the eight patients, and displaced in five of the eight. Other common radiographic findings included mediastinal shift (nine), curved and dorsally displaced trachea (seven), and axial rotation of the carina (seven). Ultrasonography was used in seven patients and considered generally useful, although variable signs were observed.