Silicosis in Cats

Silica is abundant in the environment and is an ingredient in 95% of commercial cat litter. This substance can cause lung cancer in humans, which is less likely in cats. However, felines do commonly suffer from respiratory illnesses like asthma, bronchitis, and pneumonia, which can get worse with exposure to silica dioxide dust. The respiratory disease associated with silica dust is called silicosis. This condition is a form of pulmonary fibrosis (lung scarring) that makes it difficult for the cat to breathe.

Silicosis is incurable, and can give rise to serious respiratory conditions like infections. Cats are exposed to air-borne silica dust several times a day when they use their litter box. While the term silicosis refers to respiratory disease, cats can also ingest silica while grooming themselves, resulting in GI problems like bowel obstruction. 

Symptoms of silicosis are limited to the respiratory system, including sinuses, trachea, bronchi and lungs. Exposure to silica dust can produce some of the following symptoms:

• Runny nose
• Sneezing
• Production of thick mucus that’s difficult to clear
• Coughing
• Wheezing
• Fever
• Bronchitis
• Sinusitis
• Difficulty breathing
• Lung scarring
• Signs of insufficient oxygen, such as bluish gums

Silicosis is directly caused by inhaling dust that contains silica dioxide, a respiratory tract irritant. It can affect the deepest parts of the lungs, the alveoli. As the cat’s body tries to rid itself of the silica, nodules and scarring occur that cause breathing problems.

It isn’t known whether silica actually causes respiratory problems, or if cats with respiratory problems are simply more likely to be affected by it, as one study suggests. Cats without respiratory disease are better able to clear the lungs of silica than cats with respiratory problems that pre-dated exposure to the dust.

Causes of silicosis in cats include:

• Inhaling silica particles 
• Exposure to silica oxide in the home: sand, silica gel crystals, talcum powder
• Daily use of cat litter that contains silica
• Underlying respiratory problems that weaken the ability to clear the dust from the lungs
• Inhalation of pure silica crystals that cause more harm than silica that’s bound with other substances like talc or clay  

A cat that is exhibiting symptoms of respiratory problems such as wheezing, panting, fever, or bluish gums should be taken to the vet as soon as possible. This is especially true if their cat litter contains silica but a vet visit is critical with any breathing problem.

The veterinarian will listen to the cat’s lungs to detect abnormal sounds. They will also ask questions about what the cat has been exposed to, including their litter. If possible, bring a container or the ingredient label to the vet visit. A list of ingredients copied from the container will work also. 

A pulse oximetry test will reveal whether the cat is receiving enough oxygen to their blood. Blood tests that include a complete blood count and chemistry panel will likely be done. A test to rule out tuberculosis may also be performed. A sputum examination and culture obtained during sedated bronchoscopy will confirm or rule out infectious disease like Bordetella or Pseudomonas.

A chest x-ray may show scarring or fibrous nodules and will rule out other conditions like lung cancer or tuberculosis. If necessary, the more sensitive CT scan will provide greater detail. Because silicosis can cause complications such as an enlarged heart, cardiac testing may include an EKG, cardiac ultrasound or other imaging. 

The primary treatment goals are to address underlying conditions like infections, reduce symptoms, and prevent ongoing exposure to silica. The vet may recommend switching to cat litter that contains no silica particles. Some alternatives are shredded paper, pulverized grains like corn and wheat, or simply a cat box lined with pee pads. However, many cats like the option to be able to bury their stool.

Treating infections

If an infection is present, antibiotics and fluids may be administered. Other complications like heart enlargement or low blood oxygen are addressed with medications and/or oxygen therapy. Oral or inhaled corticosteroids may be useful to reduce inflammation, and treatment of wheezing or other breathing difficulties may include tent application of warm, moist air. 

Reduce symptoms

Bronchodilators such as terbutaline or theophylline may be ordered in an oral form. Inhaled beta agonists like albuterol may be prescribed and given with a special apparatus that covers the kitty’s nose and mouth. Lung transplants are not currently available to cats.

Prevent exposure to silica

The vet may recommend switching to cat litter that contains no silica particles. Some litter alternatives include shredded paper, pulverized grains like corn and wheat, or simply a cat box lined with pee pads. Until symptoms improve, cats with silicosis shouldn’t engage in active play that will make their breathing more difficult. Enforced rest may include limiting the cat to a crate or small room.

Silicosis is an irreversible disease that doesn’t disappear with treatments that are aimed at medical support, improvement of symptoms, and prevention of further exposure.  Depending on how long the feline was exposed to silica and how long it took to take them for medical care, they may improve and return to near normal. But even without further exposure their respiratory symptoms may increase in severity, and shorten the cat’s life expectancy.

Follow-up appointments with the veterinarian are important to evaluate the status of the condition and assess the efficacy of the medications. The vet will also look for new complications and treat them.

Silicosis can be expensive to treat. If you suspect your is at risk of developing this respiratory condition, start searching for pet insurance today. Wag!’s pet insurance comparison tool lets you compare plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!

The average cost of silicosis treatment: $500 - $4,000