My Cat Died Suddenly. Was it Lung Cancer?

CatChannel and CAT FANCY cat veterinary expert Arnold Plotnick, DVM, shares information whether lung cancer or heart failure might have contributed to a cat's sudden death.

Q: I recently lost my beloved cat, Buddy, suddenly to respiratory failure and what my vet diagnosed as lung cancer.

Buddy was an indoor-only, neutered, 9 year-old cat, in otherwise excellent health. He began losing weight toward the end of November and went to my vet on Dec. 3. My cat’s vet gave him a complete exam, including full blood tests. Everything came back negative and she found nothing unusual during the exam. His heart and breathing sounded normal as well.  

My cat continued to act normal (eating, litterbox habits, etc), but in late January I noticed Buddy seemed to continue to lose weight and he had developed a type of snort occasionally when he exhaled. As my vet examined him, my cat began having trouble breathing. She took a chest X-ray and showed me white masses throughout his chest cavity and surrounding his heart. She said he had cancer that had spread throughout his chest cavity and that he probably had a few weeks left.

As bad as this shock was, nothing prepared me for what happened next. Before they could put him back in his carrier, my cat went into full respiratory failure. They gave him Lasix and oxygen, but his tongue and paw pads were completely blue. I had to make the heart-wrenching decision to end his suffering.

I’m so filled with the grief of losing my cat as I don’t understand how this could happen so quickly. I didn’t even have time to try any type of treatment. How common is cat cancer and does it usually claim its victim so quickly? I thought maybe it was his heart since I lost his littermate at the age of two from hypertrophic cardiomyopathy, but my vet said it wasn’t.

I have five other indoor cats and I’m very careful not to use anything harmful around them to clean with, etc. No one in my home smokes, so Buddy was never subjected to any type of chemicals. I also use wheat-based cat litter. I just don’t understand how this could have happened to such a young cat.  

A: I’m so sorry to hear about your cat. Without having examined Buddy or seeing the X-rays myself, it is difficult to comment on what happened, however, a few things cross my mind.  

Certainly, the description of “white masses” throughout his lungs and around his heart is consistent with lung tumors, however, pulmonary edema can have a similar appearance in cats. Pulmonary edema is basically fluid in the lungs. In dogs with congestive heart failure, pulmonary edema tends to appear mainly at the “hilus,” i.e. the area where the arteries, veins and main airways enter the lung. In cats, however, pulmonary edema can appear as patchy white areas scattered throughout the lungs. It can be easy to confuse these little patchy areas of edema with tumors.  

Given that one of Buddy’s siblings died of heart disease, I’m wondering if Buddy actually had heart disease and not lung cancer. The fact that his heart sounded normal at the time you first noticed that he was losing weight does not rule out heart disease. In fact, many cats with severe heart disease show no signs of their illness on examination — no heart murmur, no abnormal rhythm, no signs at all.

Cats are notorious for not letting anyone know that they’re sick until they simply cannot hide it anymore. This is because predators pick on the sickest in the herd, thus cats often don’t reveal they are sick until well into the course of their illness. Sadly, by the time Buddy was diagnosed, his illness was already too far along to reverse.  

The respiratory system doesn’t have very much reserve. Although he hid it well, it sounds like Buddy’s cardiopulmonary system was on the brink of failure. Unfortunately, the stress of veterinary visits – the exam, X-rays, blood tests – can push a fragile cat over the edge and cats may decompensate and go into respiratory failure. I am not suggesting that you should not have seen your cat’s vet. Obviously, you needed to. Nor does this suggest that your vet did anything wrong. The sad fact is that Buddy was gravely ill, whether due to heart failure or lung tumors. Some cats decline gradually after the diagnosis; others acutely decompensate. When it happens acutely, we’re never prepared, and the sudden nature of this can be hard to comprehend.  

You’re an excellent cat owner and it is clear that you took wonderful care of your cat. Again, my condolences on the loss of your sweet cat Buddy.

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Cats · Health and Care