Lung Lobe Torsion in Dogs


Key Points

Lung lobe torsion results in fluid accumulation in the chest and breathing difficulty

Deep-chested dogs are most commonly affected, however, other breeds can develop the condition

Surgery is the treatment of choice

Prognosis is excellent, providing that no other chest-related diseases are present

 

Introduction

  • The lungs of the dogs and cats have separate lobes. There are 4 separate lobations of the right lung and 3 of the left lung field.
  • In a case of lung lobe torsion, the lobe typically twists at the level of the base of the heart, but may also twist in the mid section of the lung lobe
  • The right middle lung lobe is the most commonly affected in most breeds. Pugs most commonly develop lung lobe torsion of the left cranial lung lobe. The accessory lung lobe torsion ( right lung) also has been reported in a series of dogs.
  • The pathophysiology of lung lobe torsion starts with a physical twist of the lung lobe along its long axis, which results in collapse of the vein of the lung lobe, but the muscular artery continues to pump blood into the lobe. The lobe becomes distended with blood and weeps bloody fluid into the chest cavity. The fluid accumulation in the chest prevents the remaining lung lobes from expanding, thus causing breathing difficulty. With time, the torsed lung lobe dies off and releases toxins into the body.
  • In some cases, underlying disease in the chest such as cancer or chylothorax may predispose the patient to developing lung lobe torsion, thus the patient will have ongoing issues even though the lung lobe has been removed. If chylothorax is present prior to surgery, the prognosis is thought to be somewhat guarded, however, one study showed that 5 of 6 dogs had resolution of chylothorax after surgery (all had the torsed lung lobe removed and 2 of these had thoracic duct ligation).

Signs

  • Breeds reported to have develop this condition include deep-chested dogs such as Afghans and Borzois, however other susceptible breeds include miniature poodles, dachshunds, Shih Tzu, Yorkshire terrier, pekinese and pugs. Cats uncommonly develop lung lobe torsion.
  • Signs typically include progressive worsening breathing problems, coughing, loss of appetite, and in some cases vomiting and diarrhea
  • Signs that a veterinarian may also note when listening to the chest with a stethoscope includes decreased heart and lung sounds

Diagnostic testing

  • Testing may include a complete blood count, chemistry profile and urinalysis
  • A chest radiograph (x-ray) will typically show fluid accumulation in the chest cavity. The torsed lung lobe will typically appear white on the radiograph due to accumulation of fluid within the affected lobe.
  • If the diagnosis is not obvious on the initial radiographs, the chest fluid is removed and the chest radiographs are repeated.
  • A fluid sample taken from the chest fluid frequently will be quite bloody.
  • Other less common tests that can help confirm a diagnosis of lung lobe torsion include bronchoscopy, chest CT scan, chest MRI, and thoracoscopy.

Treatment

  • Surgery is recommended to treat lung lobe torsion. This involves making an incision on the affected side of the chest. to expose the affected lobe.
  • The lobe is not untwisted, as this could result in release of toxins into the body and make the patient very will. The lobe thus is stapled or tied off at the hilus and removed. The photo right demonstrates a torsed lung lobe.
  • A drain is placed in the chest to allow evacuation of fluid and air from the chest cavity.
  • After surgery pain medication is administered for 3 to 4 days.
  • Intravenous fluid are administered for 24 hours after surgery.
  • Antibiotics are administered around the time of surgery
  • The patient is monitored closely for signs of breathing difficulty and low oxygen level in the blood with a pulse oximeter.

Complications

  • accumulation of milky fluid in the chest (chylothorax)
  • recurrence of lung lobe torsion (in another lobe)
  • pneumonia
  • infection of the incision

References

  1. David B. Spranklin, Keven P. Gulikers, and Otto I. Lanz. Recurrence of Spontaneous Lung Lobe Torsion in a Pug
    J. Am. Anim. Hosp. Assoc., September/October 2003; 39: 446 – 451.
  2. Andrew D. Hofeling, Andrew H. Jackson, Joel C. Alsup, and Debi O’Keefe. Spontaneous Midlobar Lung Lobe Torsion in a 2-Year-Old Newfoundland. J. Am. Anim. Hosp. Assoc., May/June 2004; 40: 220 – 223.
  3. TL Dye, HD Teague, and ML Poundstone. Lung lobe torsion in a cat with chronic feline asthma. J. Am. Anim. Hosp. Assoc., November/December 1998; 34: 493 – 495.
  4. MB Rooney, O Lanz, and E Monnet. Spontaneous lung lobe torsion in two pugs. J. Am. Anim. Hosp. Assoc., March/April 2001; 37: 128 – 130.
  5. AR Gelzer, MO Downs, SM Newell, MB Mahaffey, J Fletcher, and KS Latimer. Accessory lung lobe torsion and chylothorax in an Afghan hound. J. Am. Anim. Hosp. Assoc., March/April 1997; 33: 171 – 176.
  6. Michaël Lora-Michiels, David S. Biller, Dennis Olsen, James J. Hoskinson, Susan L. Kraft, and Jeryl C. Jones. The Accessory Lung Lobe in Thoracic Disease: A Case Series and Anatomical Review. J. Am. Anim. Hosp. Assoc., September/October 2003; 39: 452 – 458.
  7. Larue SM, Withrow SJ, Wykes PM. Lung resection using surgical staples in dogs and cats. Vet Surg 1987;16(3):238-240

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