Interstitial Pneumonia in Cats

If your cat is in respiratory distress, noted by heavy breathing and a bluish mouth, she could be suffering from interstitial pneumonia. The term “pneumonia” is commonly used in human and veterinary medicine to characterize an inflammation of the lungs, whereas the term, “interstitial pneumonia” refers to the inflammation of an exact location in the lungs, specifically the interstitium. Interstitium or interstitial can refer to a gap or narrow space in-between tissues, but can also be used when referring to a space within an organ. Therefore, when referring to a feline with interstitial pneumonia, your veterinarian is characterizing lung inflammation within the alveolar walls of the lungs. 

The symptoms of interstitial pneumonia in cats greatly depends on the severity of the disease. Your cat may begin to breathe rapidly (tachypnea), open its mouth to breathe, or may place her limbs out, away from the body, in an attempt to take more oxygen into the lungs (orthopnea). The feline’s mouth and nose may change from pink to a bluish color, known as cyanosis, due to the lack of oxygenated red blood cells. Your feline may not want to move around the house, but she will be restless and could develop muscle twitching (myoclonus). Additionally, a feline with interstitial pneumonia could develop symptoms including:

• Dyspnea (labored breathing)
• Exercise intolerance
• Tachypnea (rapid breathing)
• Cough 
• Excessive salivation
• Rhinitis (nasal inflammation)
• Conjunctivitis 
• Sneezing
• Fever
• Depression
• Anorexia (loss of appetite)
• Polyuria (excessive urination)
• Diarrhea
• Vomiting 

Interstitial pneumonia in cats can be caused by a number of underlying elements from congenital disorders to infections. Feline interstitial pneumonia is believed to be the result of the following: 

Vascular Abnormalities

• Larval migrans (parasite larvae in the lungs)
• Thromboembolism (blood clots)

Toxic Inhalation 

• Asbestos
• Silica dust
• Paraquat toxicity
• Petroleum
• Vapors
• Gases
• Dust

Infections 

• Feline Immunodeficiency Virus (FIV)
• Toxoplasmosis (Toxoplasma gondii parasite) 

Inflammation 

• Endogenous lipid pneumonia (breakdown of lung tissue)
• Bronchitis (inflammation of the bronchi)  
• Bronchiectasis (blockage of the bronchi)
• Necrotizing bronchiolitis (dead bronchial tissue) 

Cancer 

• Pulmonary carcinoma 

Metabolic Conditions 

• Pancreatitis 
• Liver disease 
• Uremia (excessive levels of urea in the blood) 

Congenital Mutations 

• Bronchiolitis obliterans (inherited mutation causing inflammation of the small airways and tissues)
• Primary ciliary dyskinesia (inherited disorder causing defective lung mechanics) 

Idiopathic Cause (unknown) 

A veterinarian will use a combination of imaging and blood tests to identify interstitial pneumonia. 

Thoracic Radiographs

An x-ray of the chest will reveal an enlarged heart on the right side, which would indicate the carbon-oxygen exchange is not occurring in the lungs. 

Arterial Blood Gas Test 

A measurement of blood gasses, such as carbon dioxide and oxygen, circulating in the body. A cat with pneumonia will present moderate to severe hypoxemia (low oxygen concentration) as a result of this diagnostic test. 

Treatment of interstitial pneumonia in cats begins will supportive care. Many cats diagnosed with interstitial pneumonia are in respiratory distress and require oxygen therapy, paired with inpatient care for constant monitoring. If the feline’s pneumonia is caused by constricted or narrowed bronchi, the veterinarian may prescribe a bronchodilator to enlarge the bronchioles. If the cat’s condition is caused by inflammation, the doctor may prescribe an anti-inflammatory drug or steroid. 

If the feline has developed interstitial pneumonia due to inhalation of a toxic substance, the veterinarian may perform a pulmonary alveolar proteinosis or bronchoalveolar lavage to flush the substance from the lungs. However, if the feline’s condition is due to a paraquat toxicity, the veterinarian may encourage the cat to vomit and urinate to remove the toxin from the body. Antibiotics and anti-parasitic medications are also a common treatment choice for infectious related pneumonia. There is no known treatment option for idiopathic or congenital interstitial pneumonia at this time. 

At-home care for a feline with interstitial pneumonia is of the at most importance. The feline should have minimal exposure to tobacco smoke, chemicals, and house dust, as these elements can make it more difficult for the cat to breathe. Maintaining a clean environment for your cat to spend the majority of her time will aid in her recovery. Many veterinarians recommend a humidifier to remove impurities from the air before your cat breathes them into her lungs. The veterinarian may ask that your cat be restricted from exercise until his or her breathing return to normal. A diet plan may be established for obese cats, as excess fat stresses the heart and lungs. 

The prognosis for interstitial pneumonia in cats is not completely positive, as some felines die due to pulmonary failure. However, catching the condition early and following the veterinarian’s orders can extend the life of your feline.