The lungs are the organs of respiration in humans and animals. Dogs have two lungs, a right lung and a left lung. The lungs are subdivided into lobes ( rounded subdivision of a bodily organ or part). Right lung is divided into four lobes while the left lung is divided into three lobes unlike human lungs which are divided into three right and two left lobes. An artery, vein and air tube (bronchus) enter the base of the lung lobe adjacent to the heart. Lung lobe torsion occurs when a lung lobe becomes twisted around the bronchus. Once the lung lobes twist at its base, the vein collapses and does not allow blood to leave the lung lobe. Because the artery has much higher blood pressure and has a muscular wall, blood continues to flow into the lung lobe. As a result, the lung becomes congested with blood and the lobe weeps fluid into the chest cavity. Accumulation of fluid in the chest causes normal lobes to collapse, causing shortness of breath in the affected dog. In addition, the torsed lung lobe dies, which results in the release of toxins into the body. This may lead to many complications, including coughing up blood, tachycardia, or shock.
This condition is more prevalent in large breed, deep-chested dogs. Male dogs are more prone to this condition than female dogs. However, small dogs such as pugs (especially those younger than four) are also at risk, most often with the spontaneous form of lung lobe torsion.
Common symptoms associated with this condition include
Loss of appetite (anorexia)
Coughing (sometimes with blood)
Difficulty breathing, especially while lying flat (orthopenea)
Increased respiration rate
Coughing up blood
Increased heart rate
Pale or bluish mucous membranes (cyanosis)