Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Hemangiosarcoma in Cats: Causes, Signs & Care Guide (Vet-Answer)

vet putting on surgical suit to a cat after surgery

You’ve noticed a lump growing on your cat, and you do the responsible thing, which is talking to your vet. Your cat’s veterinarian takes a skin biopsy after not seeing any other issues on the exam, and the results come back a few days later. Your cat has hemangiosarcoma. What does that mean, and what can you do?

divider 2 cats

What Is Hemangiosarcoma?

Hemangiosarcoma is a type of cancer. It tends to have very malignant behavior, likely related to the fact that it is a tumor that arises from blood vessels. It can spread anywhere, but it mainly spreads to the lungs. Because it is a cancer associated with blood vessels, the primary tumor can be found practically anywhere in your cat’s body, from the skin layer to the base of the heart.

Hemangiosarcoma is more common in dogs than in cats, and your vet might have never treated a case of hemangiosarcoma in cats. Hemangiosarcoma has four forms in cats:

  • In the skin or dermal layer
  • Under the skin in the subcutaneous layer
  • Within internal organs like the spleen or heart (visceral)
  • From the gums or oral tissue
hemangiosarcoma in a cat
Image By: Eleanor McDonie, Shutterstock

What Are the Signs of Hemangiosarcoma in Cats?

Cats may show various signs that could indicate hemangiosarcoma. The signs are usually non-specific and can be hard to interpret.

Your cat might develop a swelling or lump that you can feel. Your veterinarian should test the lump to look for evidence of cancer. Sometimes, vets detect visceral cancers during abdominal palpation, where an organ like the spleen or liver feels larger or has an associated mass.

You or your vet might realize something is wrong if your cat shows signs of blood loss, such as:

  • Weakness
  • Lethargy
  • Pale gums
  • Distended abdomen from bleeding
  • Tachycardia (elevated heart rate)
  • Tachypnea (elevated respiratory rate)

These signs tend to occur when your cat’s mass is bleeding. Some masses bleed small amounts into the abdomen, causing the abdomen to distend slowly. Others can rupture and cause massive internal bleeding very quickly.

Unfortunately, some cases of hemangiosarcoma are only diagnosed after a pet suddenly passes away.

What Are the Causes of Hemangiosarcoma in Cats?

We don’t know the exact cause of hemangiosarcoma in cats, and it may be multifactorial or caused by various factors. One potential cause of cutaneous hemangiosarcoma is exposure to the sun. It occurs more frequently in cats with shorter hair and lighter fur than in longer or darker-haired cats.

vet checking a white cat's face
Image Credit: MakeStory Studio, Shutterstock

How Do I Care for a Cat With Hemangiosarcoma?

If your cat is diagnosed with hemangiosarcoma, it’ll likely need a full-body workup. Your veterinarian will recommend that your cat have blood work done, radiographs (X-rays), or possibly an ultrasound. These tests help look for changes, such as metastasis.

Most pets with hemangiosarcoma need surgical intervention. The spleen is often affected and can cause bleeding, so pets may need a splenectomy. Surgery can sometimes be curative, usually when it’s just a tiny skin mass. Unfortunately, if your cat is affected by a deeper primary tumor, such as one involving the liver or spleen, surgery is not likely going to be curative.

Many pets with hemangiosarcoma have bleeding. Your cat may need supportive care through blood transfusions or fluid therapy.

Your veterinarian may recommend chemotherapy for your cat. Different protocols and medication combinations could be used, but doxorubicin is one chemotherapeutic agent that is often used.

Your veterinarian might also suggest using an herb, Yunnan baiyao. This herb helps stop bleeding, although the mechanism of action is unknown. It could be used as a palliative measure, especially if you elect not to perform surgery.

Due to the limited number of cases, researchers have little data on treatment effectiveness in cats. According to Long Island Veterinary Specialists, the life expectancy for many cats is around three months with surgery alone. It extends to roughly 6 to 9 months with a combination of surgery and chemotherapy.

senior woman cuddling her cat
Image Credit: PeopleImages.com – Yuri A, Shutterstock

Frequently Asked Questions (FAQ)

What is the treatment for hemangiosarcoma in cats?

The treatment plan your veterinarian or veterinary oncologist creates will depend on where the hemangiosarcoma is located and whether there is evidence of metastasis. According to the Veterinary Information Network, roughly 30% of visceral cases of hemangiosarcoma in cats are so severe that cats need to be euthanized at the time of diagnosis. In these other cases, surgery may help prevent or stop bleeding, but chemotherapy combined with surgery gives the longest life expectancy.

What are the signs of heart-based hemangiosarcoma in cats?

A heart-based mass can be challenging to diagnose without advanced imaging. You might notice that your cat is weaker or lethargic. In some cases, pets will develop an arrhythmia. If the mass bursts or starts to bleed, your cat may collapse or be found dead.

tired or sick cat lying on bed
Image Credit: Prystai, Shutterstock

divider 2 cats

Conclusion

Hemangiosarcoma is not common in cats, which is good because it’s a very aggressive type of cancer. Treatment tends to be most successful if your cat has a small skin mass rather than a tumor associated with internal organs like the heart or spleen.


Featured Image Credit: Maria Sbytova, Shutterstock

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Mast Cell Tumors in Cats: Signs, Causes, Care & FAQ (Vet Answer)

The mast cell tumor (sometimes referred to as a mastocytoma) is a relatively common form of feline cancer. These tumors can arise on...

vet examining cat in x ray room

Ear Cancer in Cats: Causes, Signs & Care (Vet Answer)

Ear cancer is a relatively common occurrence in cats. Two main types of tumors affect a cat’s ears. These are ear canal tumors...

cat-with-ear-infection

Cat Spleen: Our Vet Explains What it is & How it Works

The spleen often remains an elusive organ that many people have heard of, but not too many know the specifics of. And while...

a siamese cat getting examined by a vet at the clinic

Lymphoma in Cats: Causes, Signs & Care (Vet Answer)

Lymphoma, or lymphosarcoma, is the most common cancer affecting cats. It is a malignant type of cancer affecting the lymphatic system, a network...

vet checking up the cat

More related

blood is running from the cat's nose

Why Is My Cat Bleeding? A Full-Body Overview (Vet Answer)

Noticing bleeding from your cat is alarming, especially when you don’t know what’s causing it. As imagined, bleeding can occur for several different...

sick stray senior cat

Skin Tumors in Cats: Histiocytoma Explained (Vet Answer)

Skin bumps and growths in cats are not as common as in dogs, but they do occur often enough to warrant knowing a...

Example of Horner's syndrome in a cat

Anisocoria in Cats: Causes & Care Guide (Vet Answer)

Cats are known for their beautiful eyes. They even have special pupils that change shape! When fully open (dilated), their pupils are round,...

scottish fold cat checked by vet

Papillomas in Cats: Causes, Care & Treatment (Vet Answer)

Papillomas is a fancy term for warts. Warts can be singular, or there can be multiple—sometimes to the point that an entire region...

Keep reading

Why Do Cats Hate Closed Doors? 6 Likely Reasons

As any cat owner knows, cats have a lot of quirks and idiosyncrasies. One of them is a hatred for closed doors, no matter what lies behind them. Sometimes, this innate drive to get into the closed room could lead...

cat sitting near the door at home

Can a Cat Climb Down a Tree? Vet-Reviewed Anatomy Facts & Rescue Tips

Saving a cat from a tree is one of those stereotypical tropes you see in many cartoons, but have you ever stopped to think why cats get stuck in trees and are usually reluctant to get down? Cats might be...

ginger cat climbing tre

Do Cats Blink Like Humans Do? Vet-Reviewed Facts & FAQ

Cats are fascinating creatures to observe. We could watch them and ponder their various distinctly feline behaviors endlessly. Their fantastic array of eye movements is hugely expressive, making us certain of what they are communicating—either to you or to another...

close up dilute calico norwegian forest cat with eyes closed

How Many Toes Does A Cat Have? Feline Paw Anatomy Explained

Cats have amazing paws. They use them for various activities, from sensing vibrations to spreading pheromones. So, how many toes does a cat have? Most have 18 toes—10 in front and eight in back. The 5th front toe is positioned...

white cat wave his paws

Can Cats Eat Oreos? Vet-Approved Nutritional Facts

You’re dunking your favorite cookie—an Oreo—into a glass of milk and your feline is staring you down. As their eyes of curiosity check out what you have, you might wonder if you can give them a little sample. We all...

Can Cats Eat Oreos

Can Cats Eat Radishes? Vet-Reviewed Facts & FAQ

We all know that cats are carnivores. However, we also know that some cats enjoy human foods, whether animal-derived or plant-based. Many cats do not want to eat veggies unless they’re secretly hidden in their food, but some do like...

Can Cats Eat Radishes

11 Best Cat Foods in Canada in 2025 – Reviews & Top Picks

Did you know that around 50%-60% of Canadian pets are considered obese?1 Obesity is a serious health concern for cats as it increases their risk of developing potentially life-threatening conditions like cancer and heart disease.2 The good news is that...

grey cat eating food

Bengal Cat Health Problems: 9 Common Issues

Bengal cats are outgoing, social, and love to talk and interact with their owners. This breed is also incredibly intelligent and can easily learn to perform tricks. However, as with every breed, they have a few common health issues that...

Catster_Health Problems of Bengal Cats