Lung Lobe Torsion in Dogs: Understanding a Rare Condition

Radiographs of a 4-year-old Pug
Radiograph of a 4-year-old Pug

Lung lobe torsion is an uncommon condition in dogs that occurs when a lung lobe twists on its pedicle. While it may sound unfamiliar, it’s important to be aware of this condition, especially if you are a proud dog owner. In this article, we will dive deeper into lung lobe torsion, its symptoms, diagnosis, treatment, and prognosis.

What is Lung Lobe Torsion?

Lung lobe torsion is more prevalent in large, deep-chested dogs, particularly sighthounds. The right middle lung lobe is commonly affected in these breeds. However, lung lobe torsions have also been reported in small breeds like Pugs, with the left cranial lobe being primarily affected. Interestingly, male dogs tend to be more predisposed, and the condition often occurs in dogs between 4 to 5 years of age. Lung lobe torsion can occur spontaneously or be a result of various factors such as chylothorax, trauma, neoplasia, chronic respiratory disease, or previous thoracic surgery. It is believed that partial lung lobe collapse contributes to increased mobility and the occurrence of torsion.

Most lung lobe torsions lead to obstruction of the venous/lymphatic supply and bronchus, while the arterial supply is generally preserved. This obstruction causes severe congestion and consolidation of the affected lung lobe. Pleural effusion or pneumothorax can also occur.

How Does Lung Lobe Torsion Present?

The clinical signs of lung lobe torsion can be vague and may vary from dog to dog. Dogs with this condition may present with acute or chronic symptoms. Some common signs include shortness of breath (dyspnea), lethargy, and coughing. In cases where pleural effusion or pneumothorax is present, cardiopulmonary sounds may be reduced.

How is Lung Lobe Torsion Diagnosed?

To diagnose lung lobe torsion, a comprehensive hematological and biochemical analysis should be conducted. Hematological abnormalities such as neutrophilic leukocytosis and anemia may be observed. Elevated liver and renal parameters, as well as reduced albumin, are among the common biochemical abnormalities.

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Imaging plays a crucial role in the diagnosis of lung lobe torsion. Two orthogonal (lateral and dorsoventral) thoracic radiographs should be taken. These X-rays can reveal consolidation and emphysema in the affected lung lobe, pleural effusion, and pneumothorax. Additionally, the enlarged lung lobe can lead to the displacement of the trachea or bronchus, which may be evident on the radiographs. A mediastinal shift may also be present. It’s important to consider other potential causes of a consolidated lung lobe, such as infection (pneumonia), foreign bodies, pulmonary edema/haemorrhage, atelectasis, and neoplasia.

CT of a 5-year-old Labrador with a right middle lung lobe torsion.
CT of a 5-year-old Labrador with a right middle lung lobe torsion.

Thoracic ultrasonography and CT scans can also provide valuable information. These imaging modalities may reveal a soft tissue density with gas bubbles in the affected lung, as well as the presence of pleural effusion. CT scans, in particular, are highly sensitive and are often the preferred choice for investigating the thoracic cavity. They can reveal narrowed or occluded bronchi at the site of torsion and vesicular emphysema. The torsed lung lobe typically shows no significant contrast enhancement.

How is Lung Lobe Torsion Treated?

The initial management of lung lobe torsion focuses on stabilizing the dog’s condition. In some cases, thoracocentesis may be necessary to remove pleural effusion or pneumothorax.

Performing Thoracocentesis:

  • For draining pleural effusion, place the patient in sternal recumbency. Ideally, the ventral third of the 4-7th intercostal space should be used.
  • When draining pneumothorax, with the patient in sternal recumbency, insert the needle in the dorsal third of the 4-7th intercostal space. If the patient is in lateral recumbency, the needle should be inserted in the mid-thoracic region of the 4-7th intercostal space.
  • Ensure the procedure is performed aseptically using a butterfly catheter/hypodermic needle, extension tube, three-way stopcock, and syringe. Thoracocentesis can be done under local or general anesthesia. To prevent lung injury, insert the needle at a 45-degree angle to the thoracic wall, parallel to the body wall.

In some cases, oxygen therapy might be necessary. Different methods can be used to provide oxygen, such as flow-by, masks, nasal cannulation, or oxygen tents/cages. Oxygen tents/cages are considered the gold standard for delivering oxygen to critical patients. They allow for precise temperature and humidity control. However, it’s essential to keep in mind the limitations, such as limited access to the patient when the door is closed.

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The treatment of choice for lung lobe torsion is a total lung lobectomy. This surgical procedure involves removing the torsed lung lobe. A fifth intercostal thoracotomy on the affected side is typically performed. In rare cases where the exact location of torsion cannot be identified before surgery, a median sternotomy may be required. It’s crucial not to untwist the lung lobe, as this can release inflammatory mediators and endotoxins into the bloodstream. Instead, the twisted pedicle should be ligated or stapled before removing the lung lobe.

Top Tips for Performing an Intercostal Thoracotomy

Performing a thoracotomy is an invasive procedure, but it is generally well-tolerated by dogs. If unsure about the exact intercostal space to enter, opt for a more caudal site, as rib retraction provides better cranial exposure. Finochetto rib retractors are essential for facilitating exposure, and surgical stapling devices can simplify and improve the efficiency of the surgery. Before closing the thoracic wall, a thoracostomy tube is usually inserted. The thoracic wall is closed using 4-6 interrupted circumcostal sutures of large gauge polydioxanone. Having an assistant place traction on one or two sutures can help remove tension during the tying process. Gallibans can also aid in maintaining knot tension. The remainder of the thoracic wall is closed routinely.

Prognosis of Lung Lobe Torsion

In the past, the prognosis for lung lobe torsion was considered fair to guarded, with a survival rate of around 50%, which was more favorable in Pugs. However, recent anecdotal evidence and studies have shown a significantly higher survival rate, reaching up to 92% at the time of discharge[^1].

If you suspect that your dog might be exhibiting symptoms of lung lobe torsion, it’s crucial to seek prompt veterinary care. Early detection and appropriate treatment can greatly improve the chances of a positive outcome. Remember to consult with a qualified veterinarian to ensure the best course of action for your furry friend.

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