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)

Share

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

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.




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

Rescue Cats Deserve Beautiful Endings

We all know that beauty is only skin deep, and that scars always tell a story, and this is one cat with a...

Ask Dr. Paola – Help! My Cat Gets Diarrhea from Wet Food! (March 23, 2026)

Welcome to our “Ask Dr. Paola” series, where every Monday we bring expert advice straight from Dr. Paola Cuevas (MVZ) to help our...

Cat Shampoo Alternatives That Are Already in Your House

If your cat has ever gotten into something disgusting and you’ve found yourself without cat shampoo, we’re here to help. Before you panic...

Licky Treats: A Scientific Investigation into the Tube-Based Delights Taking Over Modern Cat Households

By Professor Lucifer Fluffovich, Department of Applied Snackology Human civilisation has produced many inventions of questionable usefulness: vacuum cleaners, pyramids, and the laser...

More related

Are Sunflowers Toxic to Cats? Vet-Verified Facts & Safety Tips

Bright, colorful, and towering far above most of our heads in their natural growth state, sunflowers are the kind of bloom that makes...

Birman Cat Breed: Info, Pictures, Characteristics & More

Birman cats originated from Burma (which is now known as Myanmar). Birmans are known for their unique color points, which make them resemble...

8 Cat Breeds That Get Stolen Most Often (With Info & Pictures)

Cats are becoming increasingly popular pets. While there are many great things about the rise in the popularity of cats, an unfortunate side...

Can Cats Eat Slugs? Vet-Reviewed Risks & Precautions

Cool, damp weather is the best time for slugs to come out of hiding. Because cats are hunters, they decide to take matters...

Keep reading

9 Best Organic Cat Foods in 2026 – Reviews & Top Picks

Feeding your cat can sometimes be frustrating since cats are well-known to be finicky creatures. Of course, finicky or not, it’s your job as a pet parent to purchase suitable food for your cat, and organic cat foods are among...

orange cat eating wet food

How to Weigh Your Cat: 5 Vet-Approved Steps

Though it may not be considered a necessary part of caring for cats, there are significant benefits to weighing your cat. Since cats can’t use words to tell us if they’re feeling sick, cat owners must be observant and look...

kitten on a weighing scale

10 Best Cat Deshedding Tools in 2026 – Reviews & Top Picks

With over 58 million pet cats around the nation, it’s no shock that there are tons of cat deshedding tools on the market. Because of how many tools there are, it can be next to impossible to find which tools...

grey shorthaired cat hepper brush

Why Do Cats Lay in the Middle of the Floor? 7 Vet-Verified Reasons

Cat owners everywhere are familiar with the feline antics their furry roommates get up to, but it’s not always obvious why they do the peculiar things they do. For example, why do cats just lie in the middle of the...

cat lying on the floor and looking up

Can Cats Eat Sherbet? Vet-Reviewed Facts & FAQ

Have you ever wondered, as you were enjoying a cold bowl of sherbet on a hot day, whether or not it would be OK to share a bit of your yummy dessert with your favorite feline companion? Most cat lovers...

Can Cats Eat Sherbet

6 Best Cat Foods for Kidney Disease in Canada of 2026: Reviews & Top Picks

Learning that your cat has a chronic condition, such as chronic kidney disease (CKD), can feel scary. Though this condition is not curable or reversible, support and treatment can improve your kitty’s quality of life and help it live longer....

top view of a cream maine coon cat eating dry and wet pet food from feeding dish

6 Homemade Cat Food Recipes for Senior Cats (With Pictures)

We all know that a nutritionally balanced diet made up of high quality ingredients is vital to a long and healthy life. But with so many types of senior cat food on the market, how can you be sure that...

Homemade Cat Food Recipes for Senior Cats

Is It Cruel to Keep My Cat Indoors? Vet-Reviewed Verdict & Facts

Cats are inquisitive, adventurous animals that enjoy exploring their surroundings. However, they prefer sticking close to their home territory. Some cats are born outdoors and live a feral life on the streets with no human companions to care for them....

cat-meowing-or-trilling-by-the-door

Love Cats? So Do We! Join the Catster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Catster Email Newsletter

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.