Toxic asbestos exposure can cause deadly mesothelioma, a cancer of the mesothelium or the lining of the major organs. Though more commonly associated with people, asbestos exposure has been linked to mesothelioma in household pets.

Asbestos exposure can have equally damaging health consequences as it does in people, regardless of whether it is from firsthand or secondhand exposure. Firsthand exposure occurs when physical asbestos particles are present in an environment consistently inhabited by people or pets. Secondary exposure can happen when pet owners have asbestos fibers on their clothing or skin from a different, contaminated location, and transfer the particles to their animal when they come home.

It should be noted that spontaneous mesothelioma, developing without asbestos exposure, is rare in pets.

The level of asbestos exposure for pets does not have to be chronic nor consistent to become damaging. If pets are exposed to other types of toxins, including herbicides or germicides, then there can be an increase in the likelihood mesothelioma development.

Incubation, development and presentation periods are quicker in pets, from months to a couple of years. Symptoms of mesothelioma cancer are similar to people, including nausea, difficultly breathing, dog pain, coughing, loss of weight or appetite.

Vomiting and Diarrhea
One of the more common symptoms of developing mesothelioma in pets is vomiting and diarrhea. Depending on the type of mesothelioma, pressure on the stomach lining and esophagus can make keeping food down a challenge. Pressure on the esophagus may also cause difficulty swallowing and immediate vomiting.

Diarrhea may also result from food not properly processing in the stomach or increased pressure on the entire gastrointestinal tract. The important indicator of a serious underlying issue is regular or persistent presentation of any symptom.

In people, however, nausea is a common symptom of mesothelioma, though it is hard to determine whether your pet is experiencing nausea. Though nausea may present in a lack of appetite or fussy eating, it should not be dismissed as a potential symptom. Though vomiting and diarrhea may be entirely benign, but if accompanied with any additional symptoms, this could be a sign of mesothelioma.

Weight Loss
Along with vomiting and diarrhea, your pets may not be getting enough food, nutrients or calories. This depletion may cause dramatic and risky weight loss. With weight loss, vomiting and diarrhea, your pet may also become dehydrated and suffer from vitamin depletion.

Difficulty Breathing
It may be hard to tell whether your pet is having difficulty breathing, but one of the surefire signs is repetitive and constant coughing. This is a sign of your pet struggling to breathe, possibly due to increased pressure of the expanding mesothelioma on the esophagus or lungs.

“Hot Spots”
One of the indicators of a potential mesothelioma cancer is finding lumps or “hot spots.” These areas on your pet are extremely sensitive and hard, and are usually found by petting. Reactions to these spots can help determine what underlying illness or other medical issue is occurring, and can indicate a mesothelioma presentation.

Many lumps are benign, and can be a simple fatty tumor. However, if the lumps change in shape, size, sensitivity or if more lumps appear, this could indicate mesothelioma. Hot spots can also be a sign of internal discomfort, stemming from difficulty breathing, swallowing or increased pressure on the gastrointestinal tract.
If you notice any or all of these symptoms in your pet, seek immediate veterinarian care.

Reference
The Merck Veterinary Manual. Mechanisms of Action, Indications, and Toxicities of Selected Antineoplastic Agents.

Handicapped Pets. Mesothelioma in Dogs and Other Pets.