Fibrotic Hardening of the Lungs in Cats

Pulmonary fibrosis often goes unnoticed until it is in an advanced stage, making it extremely difficult to treat. Not every cat who has pneumonia will develop pulmonary fibrosis, but it is more likely to develop in cats who are older or who are overweight.

Fibrotic hardening of the lungs, also known as pulmonary fibrosis, is a form of pneumonia that causes inflammation and scarring in the alveoli, tiny air sacs in the lungs. Over time, the inflammation and fibrous scarring cause the lung tissues to thicken and harden. This thickening affects both the flow of oxygen and the ability of the lungs to contract normally, decreasing the amount of oxygen that the rest of the cat's body receives. 

Symptoms and signs of pulmonary fibrosis typically are mild at first and slowly progress over time as the lung tissues harden. 

• Loss of appetite
• Weight loss
• Rapid breathing or increased respiration rate
• Shortness of breath
• Breathing with mouth open
• Nonproductive, dry cough
• Blue- or purple-colored mucous membranes
• Exercise intolerance
• Weakness
• Lethargy

Though the cause of pulmonary fibrosis is rarely discovered, some cats are more likely to get the condition due to the following causes:

• Genetic predisposition
• Abnormal wound healing in the lungs after injury
• Inhaled toxins or drugs
• Acute pancreatitis
• Environmental causes, such as exposure to air toxins, pollutants or smoke
• Oxygen toxicosis due to breathing at increased pressure
• Previous radiation treatments directed at the lungs

The veterinarian will need to know the cat's complete health history, when symptoms first began and a detailed list of all of the symptoms. Next, the veterinarian will examine the cat, looking at the mucous membranes in the mouth for signs of discoloration, listening to the lungs and heart with a stethoscope and taking its respiratory rate. A complete blood count, urinalysis and biochemical profile will be done. These tests will look for other conditions that could be causing breathing difficulties in the cat. 

A chest x-ray will be taken of the cat's lungs. The x-ray will look for thickened tissue that is characteristic of fibrotic hardening of the lungs. An echocardiogram may be done to view the heart and look for enlargement or any other abnormalities. A computed tomography (CT) scan may also be done if the chest x-ray is inconclusive, in order to get a three-dimensional view of the lungs. In some cases, a biopsy may be taken of the tissue. The veterinarian will put the cat under general anesthesia during this test. A tube will be placed down the cat's lungs with an attached camera. A small sample of the tissue will be removed and then sent to an outside lab for testing.

There is no cure for pulmonary fibrosis. Treatment options will help alleviate symptoms to allow the cat to get as much oxygen as possible to improve the quality of life and to keep the cat comfortable for the remainder of its life.

Oxygen Therapy

If the condition has advanced, the cat may need to be hospitalized in order to receive oxygen therapy. Oxygen will be delivered to the cat via a nose cannula or a face mask. This therapy will help the cat get enough oxygen in order to function when scarring is preventing the lungs from getting enough oxygen on their own.

Medication

Corticosteroids may be prescribed in order to reduce the lung inflammation and prevent lung infections from occurring. Antifibrotic medications may also be prescribed to stop fibrous tissue from forming. Bronchodilators may also be prescribed. Bronchodilators are inhaled medications that force the bronchial tissues to relax and the airways in the lungs to widen and remain open, increasing the amount of oxygen that can pass through.

Specialized Diet

Because most cats who are diagnosed with pulmonary fibrosis are overweight or obese, the veterinarian may place the cat on a special diet in order to help the cat lose excess weight. Weight loss will help improve the symptoms the cat is experiencing.

Pulmonary fibrosis is a progressive condition that will continue to worsen even with treatment. Cats only live on average a few weeks to several months with treatment. It's important to keep the cat in a dust-free environment that is free of toxic fumes, cigarette smoke and chemicals. Because pulmonary fibrosis can sometimes cause high blood pressure or heart failure to occur, it's important to follow-up with the veterinarian in order to monitor the cat's condition and progress.