The respiratory system’s most important function is delivering oxygen to the blood and removing carbon dioxide. However, at times, the mucus in a cat’s respiratory tract becomes too thick to allow a proper amount of oxygen to pass through the nose or mouth, causing the oxygen levels in the blood to become dangerously low. When oxygen levels become too low in the blood, veterinarians use the term anoxia or hypoxia to describe the condition. A cat in the state of hypoxia will begin showing symptoms of respiratory distress, increasing the rate of breathing to compensate for the mucus obstruction and low oxygen levels. The cat may soon fall seriously ill from the lack of oxygen in the bloodstream and develop conditions of respiratory disease.

Respiratory diseases are common in cats of all ages, but the very old and very young are at higher risk for contraction. Weak immune systems at the start of a kitten’s life and the inability to filter the respiratory system, makes this group of cats more vulnerable to contamination of disease organisms found in the air. 

The respiratory system of the cat consists of the trachea, right and left bronchi, the bronchioles found within the lungs, and the alveoli. When the cat breathes in air through the nose or mouth, it passes through each part of the respiratory system, down into the lungs to exchange oxygen in the blood. The air a cat breathes is filled with large particles of dust, dirt, and pollen that can damage the respiratory system, so the respiratory system has a filtration system to protect itself. Mucus is the thick, clear material that lines the entire respiratory system. Airborne particles land on the mucus, or mucous lining, within the nasal passageways. The large particles caught by the mucosal lining are carried down to the throat where the cat either coughs them up or swallows them. Any swallowed particles caught in the mucus lining will be destroyed by the cat’s immune system. 

Mucus is clear in a healthy cat, but a cat with respiratory disease may have brown, reddish, green, or yellow mucus coming from the nose. The excessive mucus can stuff up the nasal passageway in one or both nostrils, making it difficult for the cat to breathe or smell. As the sense of smell is depleted, a cat may lose its appetite and refuse to eat, eventually losing weight. Mucus in cats may also cause other signs, including:

The cat might increase the rate of breathing, may struggle to breathe in an attempt to restore its core oxygen levels. 

Mucus related respiratory disease in cats can be caused by inhalation of a toxic substance, allergens that cause an immune-mediated reaction, parasites, or a fungal, bacterial or viral infection. Cats that live in animal shelters, boarding facilities, and pet shops are at a greater risk of developing a mucus condition due to the fact that they are housed in close quarters with other cats. Likewise, if a cat lives in unsanitary conditions or in a tobacco smoke-filled home, the body will react by producing more mucus to filter the toxins. A full list of the causes of mucus in cats include: 

An overview of your cat’s medical history and a physical examination are the first steps in the diagnosis of mucus in cats. Your veterinarian may use a scope to view the airways, throat, and nose to determine if the mucus accumulation is a problem of the upper or lower respiratory system. Make sure to share signs you have noticed your cat displaying at home, such as coughing, wheezing or heavy breathing, as these signs can give the veterinarian clues to the condition at hand. Diagnostic tests that your veterinarian may receommend include: 

If your cat is experiencing great breathing difficulties, the veterinarian may place her in an oxygenated chamber or place an oxygen mask. Your veterinarian may then administer or prescribe medications to thin and reduce the amount of mucus in the feline’s respiratory tract. If the veterinarian believes the cat can cough up the mucus, a cough medicine or expectorant, may be prescribed. However, if the feline’s airways are too narrow or obstructed for a productive cough, a bronchodilator, such as a steroid, may be prescribed. Antibiotics are prescribed to patients who have been diagnosed with a bacterial infection and diuretics are often given to patients who have accumulated fluid on the lungs. 

Recovery and management of mucus in cats depends on the underlying condition. You can aid your cat’s recovery by listening to your veterinarian and administering all medications as directed. In most cases, your cat should have access to fluids 24/7 and her area for recovery should be clean, including the air she breathes.