Determining what is causing a cat to breathe heavily and have a loss of appetite can be difficult, as these are fairly general symptoms that can indicate any number of problems. If there are other obvious symptoms, take them into account as well, and get the cat to a veterinarian for diagnosis and treatment. In many cases these symptoms can signal a problem that is life-threatening, so a quick response is important.
Pleural effusion is the buildup of fluid around the lungs, and according to Pets MD it is the No. 1 cause of breathing problems in cats. Since pleural effusion is a symptom of an underlying condition rather than a specific illness, it may require a variety of diagnostic tests in order to identify the reason for the fluid buildup. Blood, pus, lymph or serum can all build up around the lungs, preventing them from working properly and causing the cat to have labored breathing. Often a loss of appetite accompanies this condition, since a cat that is ill in general is likely to refuse to eat.
Upper Respiratory Disease
Cats are subject to many different kinds of upper respiratory diseases, typically caused by either bacteria or viruses. A cat that is breathing heavily and has a loss of appetite may be ill with one of these. Such diseases may be acute, meaning that the symptoms appear suddenly, or they may be chronic, with symptoms that affect the cat over a long period of time. In either case, the cat needs veterinary attention. A delay could result in the cat’s death.
Toxoplasmosis is a disease caused by Toxoplasma gondii, a parasitic organism that infects cats and other mammals. According to the College of Veterinary Medicine at Cornell University, even though infection by this organism is quite common, clinical symptoms of the disease are not. When a cat shows signs of the disease, respiratory distress with labored breathing is a classic sign. The cat may have lost interest in eating due to the condition. Immediate veterinary attention is required.
The presence of cancer can cause a cat to breathe heavily if the cancer is in or near the cat’s lungs, or if it triggers a fluid buildup resulting in pleural effusion. If there are tumors in the lungs, these may be what is interfering with the cat’s breathing, causing it to breathe heavily as it tries to get enough oxygen. Loss of appetite is also a symptom related to cancer and is likely to accompany breathing problems. Treatment options will depend on the location of the cancer and its severity when it is discovered.