Pneumothorax in Dogs

Atmospheric air can gain entry into the pleural cavity from trauma caused by other animals, car accidents, and other puncturing wounds, and is called open pneumothorax. Air accumulation caused by an internal problem, such as lung disease, tumors, or infections, is considered to be a closed pneumothorax condition. One or both lungs could be affected at one time. While many cases can be successfully treated, the condition can be fatal if medical assistance is not sought promptly.

Pneumothorax is defined as an abnormal amount of free air in the pleural space, or in the tissue that wraps around the lungs. This can cause considerable respiratory distress that can lead to a life threatening condition. The most notable symptoms include many types of breathing difficulties, but you may also notice bluish gums, lethargy, or an obvious penetrating wound.

Symptoms of this condition include:

• Short of breath
• Respiratory distress
• Abnormally rapid breathing
• Labored breathing
• Shallow breathing
• Dull breathing sounds
• Coughing
• Hypoventilation
• Restlessness
• Vomiting
• Diarrhea
• Lethargy
• Fever
• Bluish skin and mucous membranes
• Poor pulse
• Pain
• Presence of a chest penetrating wound

Types

The condition of pneumothorax can be divided into these categories:

• Traumatic pneumothorax - This is the most common form, resulting from a chest injury; it is characterized by a wound that creates an open channel between the outside air and the chest cavity
• Spontaneous pneumothorax – This is a relatively rare form, and does not result from trauma; primary spontaneous pneumothorax results from the rupture of bullae or blebs, or pockets of air and secondary spontaneous pneumothorax can develop from a pre-existing lung condition
• Iatrogenic pneumothorax – This is a condition that results from medical care that has damaged the tissues covering the lungs; unfortunately, such invasive procedures may be necessary if a dog is in a life threatening situation
• Tension pneumothorax – This refers to a situation that creates a closed channel, meaning that air can enter and accumulate in the pleural space, but cannot leave; the pressure this creates can lead to severe cardiovascular and respiratory problems

Causes of air accumulation in the pleural cavity can include:

• Blunt trauma, such as car accidents, falling from a height
• Penetrating wounds, such as stabbing, gunshots, and bite wounds
• Medical procedures, such as a thoracotomy or thoracocentesis
• Bacterial infections
• Infectious diseases
• Ruptured lung abscess
• Lung conditions, such as pneumonia and various emphysemas 
• Heartworm disease
• Paragonimus infection 
• Roundworm infection
• Cancer
• Congenital bronchial abnormalities

If your dog is having difficulties breathing, it is an emergency and needs immediate treatment. Your veterinarian will observe and listen to your dog’s respiration, look at any symptoms present and physical characteristics displayed, and ask for a history of any trauma, vaccinations, heartworm, and flea and tick preventative medications. It is important to relate any and all information to aid your veterinarian in making a correct diagnosis. 

If pneumothorax is suspected, X-rays, CT scans, and ultrasounds of the chest can show the presence of free air, and may aid in a diagnosis. Further testing can help discern the cause of the air accumulation, and can include heartworm antigen testing, roundworm testing, fecal examination, and blood samples. A thoracocentesis or an exploratory thoracotomy may need to be performed, either to aid in an emergency situation, or to collect further data for a correct diagnosis. During this procedure, a culture of the lung may be taken and tested. Chest X-rays are generally taken after these invasive procedures are performed to further assess any damage.

Treatment of the pneumothorax itself will depend on the source of the air, the amount of air accumulated, if it is an open or closed channel, and any other clinical signs your dog is presenting. If the air needs to be evacuated, this can be done through a thoracocentesis, a procedure that uses a needle to penetrate into the pleural cavity to extract air, fluid or tissue samples. It is used for both diagnostic exploration and as a treatment. It is always recommended when there is a penetrating injury. X-rays are always taken after this procedure. A thoracocentesis is only performed in cases where your dog’s respiration is compromised. Other procedures may include placing chest tubes and administering supplemental oxygen. 

Once your dog is stabilized, the cause of the pneumothorax will be treated. If there was a blunt trauma or penetrating injury involved, surgery to repair wounds may be needed. Wounds are then sealed with dressings, and your dog is monitored. Any lesions or tumors identified in the lungs, lung diseases, or parasitic or bacterial infections will be treated appropriately as needed. If blebs or bullae are present, a pleurodesis may be performed to eliminate the space between the membranes surrounding the lungs.

If the pneumothorax does not resolve after treatment, further exploratory procedures may be needed.

The recovery is good for many cases of spontaneous pneumothorax, as long as treatment is prompt. You should see an immediate improvement in your dog’s breathing after treatment, although there can be a reoccurrence. Other types of pneumothorax have variable rates of recovery. Reoccurrence can also depend on the successful treatment of the underlying condition.