Lung-lobe torsion

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Right lateral radiograph showing aeration in the dorsal portion of the consolidated left cranial lung lobe due to lung-lobe torsion[1]

The torsion of a lung lobe at its hilus is a rare but life-threatening condition in dogs, commonly reported in large deep-chested breeds.

Torsion occurs when the lung lobe rotates around the bronchus and vascular supply and remains in that position. The patient may present in an acute, fulminant respiratory crisis; however, more subtle clinical signs have also been reported. Lung lobe torsion may be secondary to an underlying pathology or spontaneous and idiopathic[2].

Despite their small size, Pugs also appear to be predisposed to the condition[3], possibly due to bronchial cartilage dysplasia, resulting in bronchial hilus instability in brachychephalic breeds, making a lobar torsion more likely.

Lung-lobe torsion in dogs usually occurs secondary to accidental and surgical trauma, pleural effusion, chylothorax[4] and pneumothorax[3]. A predilection to torse the right middle lobe has been observed. This has been attributed to the narrow shape of the right middle lung lobe, its thin bronchovesicular pedicle, and its poor attachment to surrounding structures[5].

Clinically affected dogs present with dyspnea, tachypnea, lethargy, anorexia, pyrexia, cough and vomiting[6]. Less commonly pale mucous membranes, cyanosis, pain on abdominal palpation and diarrhea are seen[7].

While a single instance of acute collapse secondary to lung-lobe torsion has been reported in a dog[8], tussive syncope secondary to lung-lobe torsion can also occur[1].

While survey radiographs, angiography, computed tomography, ultrasonography, and bronchoscopy have all been used in the diagnosis of lung-lobe torsion, the imaging technique most commonly used to make a diagnosis is survey thoracic radiographs[9].

Radiographs usually reveal variable degrees of lung lobe opacity, vesicular emphysema pattern[10] and pleural effusion. There is usually enlargement, consolidation and emphysema of the affected lung lobe, with mediastinal shift to the contralateral side[11].

Ultrasonography may show hyperechoic consolidated lung lobe which are swollen with small irregular areas of cavitation.

A differential diagnosis includes atypical lobar pneumonia, intrapulmonary hemorrhage or pulmonary neoplasia (e.g. lymphoma, bronchial carcinoma).

Treatment usually requires lung lobectomy, which is often curative.

References

  1. 1.0 1.1 Davies JA et al (2011) Tussive syncope in a pug with lung-lobe torsion. Can Vet J 52(6):656-660
  2. Gicking J & Aumann M (2011) Lung lobe torsion. Compend Contin Educ Vet 33(4):E1-E5
  3. 3.0 3.1 Neath PJ et al (2000) Lung lobe torsion in dogs: 22 cases (1981–1999). J Am Vet Med Assoc 217:1041–1044
  4. da Silva CA & Monnet E (2011) Long-term outcome of dogs treated surgically for idiopathic chylothorax: 11 cases (1995-2009). J Am Vet Med Assoc 239(1):107-113
  5. Breton L et al (1986) Successive torsion of the right middle and left cranial lung lobes in a dog. Can Vet J 27:386–388
  6. Spranklin DB et al (2003) Recurrence of spontaneous lung lobe torsion in a pug. J Am Anim Hosp Assoc 39:446–451
  7. Murphy KA & Brisson BA (2006) Evaluation of lung lobe torsion in Pugs: 7 cases (1991–2004). J Am Vet Med Assoc 228:86–90
  8. Rooney MB et al (2001) Spontaneous lung lobe torsion in two pugs. J Am Anim Hosp Assoc 37:128–130
  9. D’Anjou MA et al (2005) Radiographic diagnosis of lung lobe torsion. Vet Radiol Ultrasound 46:478–484
  10. Schultz RM et al (2009) Radiography, computed tomography and virtual bronchoscopy in four dogs and two cats with lung lobe torsion. J Small Anim Pract 50(7):360-363
  11. Seiler G et al (2008) Computed tomographic features of lung lobe torsion. Vet Radiol Ultrasound 49(6):504-508
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