Monday, May 27, 2013

Cancer in Cats: Hemangiosarcoma

Cancer in Cats: Hemangiosarcoma

The series for Pet Cancer Awareness Month continues with a look at hemangiosarcoma. First the good news: this is a much rarer cancer in cats than it is in dogs, representing only about 2% of all feline cancers. The bad news is that unless it's the skin form of the disease, it's not a diagnosis you want to hear.

What is Hemangiosarcoma?

In a healthy cat, there are cells lining all the blood vessels in the body. They are called endothelial cells. These cells help the blood to flow smoothly through the body.

Hemangiosarcoma is a malignant tumor affecting the endothelial cells. It is sometimes called HSA. The tumors that form as a result of it tend to be blood-filled and prone to rupturing. It can occur anywhere in the body, since the blood vessels are everywhere.

There are four forms of HSA in cats. One affects the skin (Dermal). The second attacks the area just under the skin (Subcutaneous or Hypodermal), although some experts group this type together with the dermal form, referring to them both as Cutaneous. Another affects the internal organs (Visceral) and is the most rare in cats. The fourth form is found in the mouth (Oral). HSAs can also occur on the bones, although this is usually due to their having spread from the primary location.

The dermal and subcutaneous forms of hemangiosarcoma are the most common in cats. They are often located on the cat's head or rear legs. About half of the HSAs diagnosed are of these forms.

Subcutaneous tumors spread to other areas of the body about 60% of the time. Often, hemangiosarcoma spreads to the lungs. Spreading is rapid and causes bad internal bleeding that can be life-threatening.

If on the heart, bleeding will cause blood to fill up the sac surrounding the heart (pericardium) so that the cat's heart will not have room for the blood flowing through it.

In cats, the visceral form of hemangiosarcoma can also occur in the intestines, which also have a lining of endothelial cells.

When it spreads to the bones, hemangiosarcoma can affect the spine, pelvis, skull, and legs.

What Causes Hemangiosarcoma?

Because this type of cancer is so rare in cats, little research has been done on it other than anecdotal observations. Many vets may even be unfamiliar with it. Sun exposure may be a factor in the development of the dermal and subcutaneous forms. Cats with thin or lighter-colored coats would be more at risk for this if they spend a long time basking in the sun.

Older cats seem more likely to get this type of cancer, although keep in mind that it is rare in cats compared to dogs. There has been no determination of a correlation between HSA and any particular breed of cat.

Although causes of it in cats are unknown (other than the connection with sun exposure), in humans it can be caused by exposure to certain chemicals. As with most types of cancer, it's likely a combination of factors, both environmental and genetic, as well as viral exposure, that come together in the perfect storm for an individual cat.

What Symptoms Would I Look For?

Your cat may have a dark red, purple, or bluish-black raised nodule on the skin, more commonly on the head or the back legs or paws. Have your vet test it quickly, as the dermal form can quickly metastasize (spread) internally if not removed.

If the tumor is subcutaneous, the skin on top of it may look completely normal. You may see some swelling that appears firm and soft, but moves (because it is filled with blood) when you touch it. The skin may look bruised over the swollen area. It may pop up fairly quickly.

In the spleen, you likely wouldn't notice much unless your cat's abdomen is distended from an unusually large tumor. There may be vomiting and diarrhea. Your cat may be lethargic or refrain from vigorous play.

As the cancer grows, your cat may hide more. Kitty may pant or gasp for breath, or seem to have difficulty breathing. The cat may seem confused or "out of it". The gums may be pale from anemia.

If the tumor is in the spleen or the heart, it can rupture and bleed profusely, even if benign. This is a life-threatening situation. The sudden collapse of your cat due to this internal bleeding may be the first symptom you see. The cat may be crying from pain at this point. Emergency veterinary care is required in these cases, and may still not save your cat's life.

Oral hemangiosarcoma tumors would usually appear on the gums. There will likely be a loss of appetite accompanied by weight loss as eating becomes more painful and the cat feels worse.

If the cancer has spread to your cat's bones, the cat may limp. You may notice a swelling in a leg or near any bone. The cat may break a bone for no apparent reason. Or you may notice bleeding as the first symptom.

How is Hemangiosarcoma Diagnosed?

Make notes on any of the above symptoms you notice, including when you notice them, so that you can give your veterinarian the most complete information possible.

In addition to performing a thorough physical exam on the cat, your vet will need to take some of kitty's blood and urine for testing. An X-ray or ultrasound of the chest and abdomen will be taken. If the abdomen is swollen, some of the fluid will be drawn for analysis. An EKG (electrocardiogram) may be done to check the heart rhythm. A sample of tissue from the tumor will be taken for biopsy.

The forms of the cancer affecting the heart and spleen can only be seen on X-rays. The heart will appear round on the image, as all that can be seen is the blood-filled sac around it. Some of the pericardial fluid may be drawn for analysis.

Even with the dermal form of this cancer, imaging may be done on the lungs, abdomen, and heart to check for signs that the cancer has spread to those areas. This is especially important for the subcutaneous tumors, as they are often not discovered as early.

How Are the Dermal and Subcutaneous Forms of Hemangiosarcoma Treated?

Skin tumors are removed surgically. A biopsy will be done on the tissue that's removed to make sure all of the tumor was extracted. There may also be a few months of weekly chemotherapy to make sure all the cells are killed. The chemo will probably make your cat's coat fall out in places or change color, and will make him feel bad after each session. There may be behavioral changes resulting from the cat's discomfort during this time.

Especially with subcutaneous tumors, complete removal is often difficult. Radiation may be used on these sites. Once treated, monitor your cat closely with frequent vet visits to make sure the cancer does not return.

It is important to seek treatment quickly. In addition to being quite volatile and subject to rupture, these bloody tumors spread quickly and will become fatal within a very short timeframe.

After surgery, make sure your cat is on a high-quality diet. This will give the cat's body the appropriate nutrients to recover from the surgery and remain stronger during chemo. You may need to syringe-feed the cat if he won't eat. The vet may prescribe medication for pain, which should be given with great care to avoid overdosing the cat. Kitty will need a quiet, calm place to heal after surgery and may need a special collar to keep him from licking or scratching at the wound. Keep your cat out of the sun or get a coating put on your sunny windows that includes a UV blocking tint.

If the cancer returns, whether in the same or another location, your cat may need multiple surgeries, one for each recurrence. Eventually, one of these may claim your cat's life.

How Are Other Forms of Hemangiosarcoma Treated?

In about 30% of cats, visceral HSA (the one affecting the body's major organs) is not discovered until it is too late to be treated and the cat must be euthanized when diagnosed. Or the diagnosis may not even be possible until after the cat's death, during an autopsy.

A tumor on the heart will be discovered in an emergency situation. The blood in the pericardium must be removed with a needle to save your cat's life. The first course of treatment is to stabilize your cat, who will likely be in shock.

Most of these tumors will already have spread by the time they are discovered. If the tumor can be surgically removed, chemotherapy will be used following surgery.

If the tumor is on the spleen, the cat's spleen must be removed. This is followed by chemotherapy.

What's My Cat's Prognosis With Hemangiosarcoma?

The visceral forms of hemangiosarcoma are commonly fatal, with the cat living less than a year after diagnosis.

For dermal and subcutaneous forms, try to find a vet who has personal experience with hemangiosarcoma in cats. Cats have a much better prognosis than dogs with these forms of the disease. Once the tumor is completely removed and if it has not metastasized, the cancer may be cured for a little while. This is much more the case with cats than it is with dogs. If removed completely, as determined by a biopsy of the removed tissue, the tumor should not grow back. It may have already spread without discovery, however, and crop up someplace else shortly afterward.

Subcutaneous tumors tend to recur about 60% of the time.  By itself, surgery provides a "median" survival time of 6 months, meaning that half of all cats treated lived longer than 6 months, while half did not live 6 months. Chemo is needed as a follow-up to surgery for best results.

If treatment is given for the visceral form and your cat survives it, hemangiosarcoma can go into temporary remission...the operative word there being "temporary". Surgery alone can give your cat around 4 months of additional life. Surgery with chemotherapy may give around 8 months of life (total, not on top of the 4 with surgery alone). The median survival time is 77 days. As stated earlier, this is not a diagnosis you want to hear. HSA is never completely cured.

To protect your cat from hemangiosarcoma, minimize kitty's exposure to the sun. You can get a clear film for your windows that filters UV rays; it'll have the added advantage of reducing fading of your floors and furniture! If your cat goes outdoors, make sure there is shade readily available. There's also sunscreen that can be applied to light-colored or hairless cats. Do not force your cat to go outside in the sun if he doesn't want to. Limit exposure to chemicals as much as possible (not an easy feat in our modern society). Beyond that, there's not much you can do.

Note: The image shown above this post is of a growth that appeared on my little Vixen's chin for the last few years of her life. A biopsy on it did not reveal any malignancy, but it would occasionally fill with blood and rupture, so I used it for the image associated with this type of cancer. It's not necessarily what a hemangiosarcoma looks like, but because they're so rare in cats, there aren't a lot of images of them.

Sources: "Hemangiosarcoma", Wendy C. Brooks, DVM, DipABVP, Veterinary Partner; "Hemangiosarcoma in Cats and Dogs", Lap of Love; "Hemangiosarcoma in Cats", Dr. Kimberly Cronin, Pet Place; "Hemangiosarcoma of the Bone in Cats", Dr. Jeffrey Philibert, Pet Place; "Skin Cancer (Hemangiosarcoma) in Cats", Pet MD; "Feline Hemangiosarcoma vs. Canine Hemangiosarcoma: Different for Cats Than Dogs", Melissa Nott, Yahoo! Voices; "Feline Subcutaneous Hemangiosarcoma: Joey's Story", Melissa Nott, Yahoo! Voices; "Hemangiosarcoma in cats: 53 cases (1992-2002)", National Institutes of Health; "Feline Hemangiosarcoma", Barbara Yarington, 910 Pets; "Hemangiosarcoma in Cats", Winn Feline Health; "Hemangiosarcoma in Cats and Dogs", Pet Cancer Center; "Research Update: How effective is surgical excision of feline cutaneous hemangiosarcomas?", Joseph Harari, MS, DVM, DACVS, DVM360.


  1. I lost my baby to this cancer last year. She was only 10 years old. We first noticed a lump on her abdomen in March, maybe the size of a hazelnut. Our vet used a needle to "aspirated" but only saw blood in the sample.
    We found out later that is quite normal for this type of cancer. Long story short, we put her to sleep in early November.

  2. I have a 15 yo cat with this cancer in his leg. I noticed him losing weight his bloods had been good. The tumour appeared out of nowhere. I've had it removed twice. The second time on 9 Jan this yr. they took so much skin there was nothing to stitch but they couldnt get it all. The skin was granulating but tonight it looks bulbous and there's fresh blood and tissue on his bed. It's bright red. I think I'm about to lose my boy

  3. This is a good article - thank you. My 14 yr old cat had a lump removed from her chest a few months ago, which biopsied to be this kind of cancer. Recently I have found 3 new lumps, in a cluster at the same area. I'm taking her to the vet as soon as I can get an appt. I know there are options (more surgery, chemo), but I don't want to put her through this ordeal again just to gain a few more months with her. After her last surgery, she started excess self-grooming and hasn't completely stopped.

  4. We found out that Bessie had the visceral type Thanksgiving 2016. I had noticed her not acting well and got her to the Vet that morning. By the time I reached the Vet she,was shutting down. The Vet was able to stabilize her and an ultrasound found a mass on her spleen that had ruptured. We removed her spleen because we didn't think she has this type of cancer due to its rarity. I chose not to do chemo. She's been doing well for almost a year but we found out today that the cancer is back and the prognosis is 3 to 4 months. I'll keep her as comfortable as possible for as long as possible but I can tell my girl is getting tired.

  5. Five years ago, almost to the day, a vet removed what she said was a “cyst with a blood supply” from my cat’s left rear paw. About a year ago, I noticed that it was coming back. This past week, my new vet removed the mass—about the size of a large grape and black in color—and amputated part of her paw. Biopsy results revealed it was NOT a cyst, but a hemangiosarcoma. My cat is 11 now and this surgery was hard on her. The vet said the entire tumor was excised, but it may return—on her paw or internally. I’m going to get her through this recovery and then go on to give her a great life (per usual) for as long as God gives us. Thank you for this comprehensive, informative article!

  6. My sweet Mimi (11) was literally okay until she wasn't. Then, one day she collapsed and was found to be severely anemic. An ultrasound revealed an "abnormal spleen" and surgery was immediately recommended. After her spleen was removed and sent to pathology, it was determined she had visceral hermangiosarcoma. Though prognosis was poor, we started chemotherapy (October 17, 2019). Again, and after recovering from her surgery, she was great. I use to tell people that if I didn't know she had cancer, I wouldn't have know she had cancer as despite chemotherapy and a splenectomy, she had great quality of life. When Thanksgiving came she started to rapidly decline, but she continued to fight with all of her being. She had good days and bad days, but when the bad days became the norm, I could not let her suffer any longer. On December 14, 2019, not even 2 months after her diagnosis, my sweet Mimi's journey came to an end. I have since learned that more than likely, that she had the cancer for a good 6 to 9 months before the splenectomy. There is nothing that we could have done, as this type of cancer is extremely aggressive and lives in the blood. It truly was a silent killer and I'm so devastated that she fell victim to such an illness. Mimi was bottle fed as a baby and was my "furry daughter." My heart will be forever broken.