Who knew 50ml of fluid had accumulated in her chest? My cat was diagnosed with hemangiosarcoma, and I learned "key points for post-operative follow-up care."

Hemangiosarcoma, a malignant tumor where the cells forming blood vessels become cancerous, is commonly seen in dogs but rare in cats. However, my Jiji contracted this unusual disease and passed away.

Still, I learned a lot during his fight against the illness. This time, based on my real-life experience, I will share important points to keep in mind when monitoring hemangiosarcoma – "points that require a vet's examination" and "precautions for early detection of abnormalities."

Hemangiosarcoma in the intestines was removed... The possibility of metastasis was high.

In Jiji's case, hemangiosarcoma developed in his intestines. The process leading to a definitive diagnosis was long, so if you want to know more, please see here.

After the surgery, the veterinarian told me, "We removed as much as we could, but I can't definitively say that it was completely removed." They also said, "There was bleeding from the tumor before removal, so there's a high possibility that cancer cells traveled through the blood vessels and metastasized somewhere," which left me feeling despair.

I wanted him to live as long and peacefully as possible. I felt that way, and because there are so few cases of hemangiosarcoma in cats, there's so much that's unknown, so I also thought that perhaps a prayer for "remission" might be answered.

Perhaps if I hadn't changed my mindset like that, I might not have been able to cope emotionally.

After that, I took Jiji to the vet once a month for regular ultrasound examinations.

The veterinarian always spent about 15 minutes carefully checking organs other than the intestines that are prone to metastasis, for which I was grateful. During routine check-ups, they would show me the ultrasound and explain his condition clearly.

According to the veterinarian, in dogs, hemangiosarcoma often metastasizes within about two months even after the tumor is removed. Perhaps because of that, every time they would praise him, saying, "This one is progressing very well," and tell me, "We don't see anything suspicious in the spleen or kidneys, which are prone to metastasis."

However, there seemed to be a persistent inflammation around the area of the removed intestine. The ultrasound examination couldn't definitively confirm it was a tumor, so the veterinarian told me, "It might be a tumor that couldn't be completely removed, or it might be post-surgical inflammation. I'm sorry that I can't be definitive."

Although the inflammation was concerning, Jiji was energetic and had a good appetite, leading a perfectly normal life. So, after consulting with the veterinarian, we continued with regular check-ups and observation.

However, I was instructed to seek immediate veterinary attention if there were any small abnormalities, such as loss of appetite, frequent vomiting, or blood in the stool.

Concerned about coughing and crying when being held, I went to the hospital.

About three months after the tumor removal surgery, I was told during a routine check-up that there was a small amount of ascites. However, it wasn't enough to require drainage, and no signs of metastasis were seen in other organs.

Since he had a good appetite and was energetic, and there were no unusual changes in his daily life, we decided to continue monitoring the ascites and conducting ultrasound examinations.

However, during the Golden Week holidays in 2025, Jiji coughed unusually, which worried me... In fact, Jiji had occasionally coughed even before his hemangiosarcoma was diagnosed, so I thought, "Maybe it's a metastasis..."

He had an appetite and was energetic, but when I picked him up and hugged him tightly, he would let out a cry, "Nya!", just like he did right before the hemangiosarcoma was diagnosed, whether it was from happiness or pain.

A chest X-ray revealed "50ml of pleural effusion"...

Anxiety mounted, and I immediately went to my regular vet. I prefaced by saying, "I'm sorry for being overprotective..." and explained the symptoms. First, they performed the usual ultrasound examination.

The ultrasound examination showed no particular abnormalities. However, the veterinarian said, "There's probably no problem, but let's take an X-ray just to be sure."

And what was revealed was the fact that pleural fluid had accumulated. Honestly, when I heard that, I thought, "If ascites can be seen on an ultrasound, shouldn't pleural fluid be visible too...?" and asked the veterinarian why it hadn't been detected.

Then, the veterinarian explained, "We were examining the spleen, kidneys, and other organs around the operated intestine, as well as the heart and other chest organs, but pleural fluid can be missed if you're not specifically looking for it..." When I heard that, I honestly felt a surge of anger, thinking, "If only they had examined him more thoroughly..."

However, seeing how quickly the pleural fluid accumulated afterward, my feelings changed. In Jiji's case, about 100ml would accumulate each time he went to have the fluid drained once a week, and towards the end, the amount was so much that even once a week wasn't enough.

However, when I noticed the abnormality, had an X-ray examination, and the pleural fluid was discovered, only about 50ml was drained. I began to think that perhaps it wasn't an oversight by my regular veterinarian, but rather that the pleural fluid had just started to accumulate.

During routine check-ups, it's also important to examine areas that haven't been considered.

What I learned from this experience was the importance of asking the veterinarian to perform as many tests as possible to detect not only abnormalities around the surgical site but also abnormalities in distant organs at an early stage, after my cat had hemangiosarcoma surgery.

In Jiji's case, since the hemangiosarcoma was in his intestines, I was concerned about the slightly accumulated ascites, but ultimately, it was the pleural effusion that took his life. It was an abnormality in a completely different area than what I had been focusing on.

(※By the way, the ultrasound examination showed no obvious metastasis to the lungs or other organs.)

Of course, veterinarians are animal medical professionals, so they do their best to detect abnormalities throughout the body early, to some extent, even if the owner doesn't mention it.

However, as an owner who is always with their cat, there are some abnormalities that only you can notice. In such cases, it's very important to have your cat's body examined from a different perspective than usual, without hesitation.

Also, during routine check-ups, asking the veterinarian specific questions like, "What kind of abnormalities should prompt an immediate visit?" might help you define what constitutes an "abnormality" in your own mind.

Being able to quickly notice minor changes and take them to the vet can help extend their life.

Perhaps there could be an abnormality in areas that are thought to be "healthy," not just in the inflammatory areas after surgery that are always monitored. I felt that it is important to have such a perspective when fighting malignant tumors, not just hemangiosarcoma.

The current situation is that there is still little information available regarding hemangiosarcoma in cats. Of course, the affected area and symptoms vary among individuals, but my hope is that by gathering many shared experiences, more cats will achieve remission, and more owners will be able to have a fulfilling journey with their sick pets.

...Perhaps for a while, my cat essays will continue to feature rather heavy topics like fighting illness, pet loss, and cremation. I apologize if it feels "hard to read." But I believe that "lifelong care" – being by their side until the very end – means this, so I want to cherish and weave together what I experienced and what Jiji taught me.

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