Mesothelioma in Cats

Mesothelial cells line the interior of your cat’s chest cavity and internal organs. These cells play an important role in protecting your cat. In mesothelioma, abnormal cell division or growth begins to occur within this lining in some part of your cat’s body. This typically begins in the thoracic, or chest cavity. Once the cells mutate, they begin to rapidly spread to other parts of the body, causing small nodule like tumors, thickening of the linings throughout the cavity and displacing the body’s vital organs. Mesothelioma is known as an exudative type of cancer, meaning that it exudes or causes the release of a large amount of fluid which can also cause severe problems for your cat.

As with many cancers, mesothelioma can begin with only subtle symptoms. As the cancer spreads throughout the body, symptoms will rapidly progress until your cat is very sick. Signs to watch for include:

• Lethargy
• Vomiting
• Difficulty breathing
• Pleural effusion (fluid in the lining of the pleural cavity)
• Excess buildup of fluid in other affected cavities
• Bloated appearance of belly, caused by buildup of fluid

The most widely known cause of mesothelioma in both cats and humans is from exposure to asbestos. Asbestos is a harmful chemical that is used to insulate and line many older buildings, pipes, and other structures and is still in use today. Your cat may be exposed to asbestos if it is allowed outdoors and comes into contact with asbestos at a factory or other area where asbestos is in production. They may also become exposed if you bring asbestos home on your clothing. 

Asbestos fibers are very small and lightweight. The fibers are easily inhaled and then attach themselves to the mesothelial lining throughout your cat’s body. Once attached, the fibers cause inflammation which leads to the production of mesothelioma by instigating an immune response and unnatural cell mutation and growth.

A diagnosis of mesothelioma in your cat will begin with a thorough physical exam performed by your veterinarian. At this exam you should provide your vet with a medical and physical history of your cat, paying especial attention to details regarding approximate onset of symptoms, escalation, and whether your cat could have potentially come into contact with asbestos. 

Your vet will order a complete blood profile for your cat. This will include a quick insertion of a needle in order to withdraw a small amount of blood. The blood will be sent to an outside laboratory for a complete analysis of any abnormal levels or presence of infection.  Your vet will also use a common stethoscope to listen to the chest and breathing sounds of your cat. Since fluid buildup in the chest cavity and the sac surrounding the heart are classic indications, a muffled sound such as that heard when this type of fluid buildup is present, is a strong indicator of the presence of the disease.

Finally, your veterinarian may order x-rays or ultrasound imaging of the potentially affected areas of your cat. These images will help identify the presence of any tumors or masses and can also diagnose the thickening of the mesothelial lining that is often caused by mesothelioma. These procedures can also detect a buildup of excess fluid.

Treatment of mesothelioma in cats begins with treatment of the secondary symptoms of the condition. If there is a significant buildup of fluid within your cat, it may need to be hospitalized so that your vet can perform specialized procedures to drain this fluid which should give your cat some relief. This may involve inserting special tubes or using fine needles inserted with the help of an ultrasound, to remove fluid buildup.

Surgical removal is generally not an option with mesothelioma, given that the tumors are typically numerous, small in size, and can affect the entire lining as opposed to a single area. Treatment will primarily focus on ways to alleviate any compression on vital organs.

While chemotherapy has been shown to be an effective treatment method in dogs and humans, unfortunately, the types of chemo drugs that treat mesothelioma are toxic to cats.

Curing your cat of mesothelioma is a difficult task. You and your vet may focus on eliminating symptoms that cause quality of life issues. Your cat will need regular vet visits to drain the continuous fluid buildup. In addition, your vet may want to perform regular x-rays or other imaging in order to confirm that the cancer has not metastasized or spread to other bodily organs.

It will be important to prolonging and increasing the quality of life in your cat that you closely follow any and all medication and treatment courses prescribed by your vet.