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What is Fibrosarcoma?

When describing feline fibrosarcoma, vets explain that this type of cancer begins in individual cells within connective tissue, as well as just under the surface of the cat’s skin.

Fibrosarcoma is a form of soft-tissue cancer that is common to cats. Fibrosarcoma is aggressive in the cells where it first appears, but slow to spread to other body organs or systems. Fibrosarcomas begin in the fibroblasts of the skin (cells in connective tissues) and in subcutaneous (under the skin surface) connective tissues. While some grow slowly, others may grow more quickly. After being surgically removed, fibrosarcomas can grow back. This type of tumor is most often caused by papillomavirus, the virus that causes warts.

Fibrosarcoma Average Cost

From 469 quotes ranging from $2,000 - $10,000

Average Cost

$6,000

Symptoms of Fibrosarcoma in Cats

The cat’s owner is most likely to notice lumps just underneath the surface of the cat’s skin. These lumps can appear anywhere on the cat’s body: the head, legs, in the mouth and anywhere else on its body. Other symptoms include:

  • Lumps may be fleshy or firm
  • The cat may not feel pain from the lumps
  • Lumps are irregularly shaped

Fibrosarcomas can also develop inside the cat’s body; usually on its spine, in the pelvis, or in its ribs. Advanced fibrosarcoma causes the cat to:

  • Have difficulty eating
  • Lose its appetite
  • Become dehydrated
  • Painful walking
  • Become lethargic
  • Develop mysterious bleeding in its mouth
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Causes of Fibrosarcoma in Cats

Cats can develop fibrosarcoma for one of three reasons. If the cat is older, it may be more prone to developing this particular form of cancer. 

Some vaccines have been linked to the development of fibrosarcoma, but these occurrences are rare. When fibrosarcoma develops as the result of vaccinations, it is called “vaccinosarcoma” or vaccine-induced sarcoma. While vets still recommend that cat owners have their pets vaccinated, vets will give one vaccine, such as the rabies shot, in one leg, then give the feline leukemia (FeLV) vaccine in the opposite leg. 

The adjuvant within the vaccination is usually aluminum. This ingredient helps to keep the killed virus within the area where the injection was given for a short time so the body can develop an immune response. By keeping the killed virus in one small area, it makes it easier for the cat to develop a localized inflammation, which can stimulate the development of the sarcoma. Cat owners should discuss modifying their cat’s vaccination schedule with the vet.

The third cause is a mutant form of FeLV, called feline sarcoma virus or FeSV, which can lead to fibrosarcoma. This occurs in younger cats, who develop multiple tumors.

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Diagnosis of Fibrosarcoma in Cats

If the vet suspects a fibrosarcoma, they will run several tests. First, they will give the cat a full physical exam, from head to tail, so they can rule out any other causes of the lumps. Making an early diagnosis while the cancerous lump is still small gives the cat a higher chance of recovery and survival. Early detection also allows the vet to prescribe more options that give the cat a more positive outcome.

They will order routine testing, such as a biochemical profile, urinalysis and a complete blood count. These tests allow the vet to rule out other illnesses, other than a low lymphocyte count.

Next, the vet will order X-rays or a CT scan, which allow them to see the lump and whether the cancer has spread to other parts of the cat’s body. An X-ray shows a fibrosarcoma as a soft tissue mass.

Once the vet begins to narrow their diagnosis down, they will do a fine-needle aspiration or biopsy of the lump so the cells can be examined under a microscope. 

Finally, the vet does a FeLV test. This will allow them to determine if the fibrosarcoma has developed because of FeSV.

Once the vet has made a diagnosis, the pet owner will need to work with them to start cancer treatment and begin an at-home treatment regimen so the cat has a better chance of survival.

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Treatment of Fibrosarcoma in Cats

Treatment options depend on where in the cat’s body the cancer is located. It’s much easier to treat cancer that has not spread to other organs, because they spread with nearly invisible tentacles. This makes complete eradication of the cancer even more difficult because, if any cancer cells remain in the cat’s body, new cancers can develop.

Surgery

Depending on where the cancer is located, the vet may suggest surgery to remove the cancer, along with the removal of some of the healthy tissue. Limb amputation may be necessary.

Radiation

Post-surgery, the vet may prescribe radiation, which helps to destroy any remaining cancerous cells. Radiation treatment begins about two weeks post-surgery.

Chemotherapy 

Chemotherapy may also be prescribed. This can begin before surgery so the tumor can be shrunk, making removal easier. After surgery, chemo may be given again so remaining cancer cells can be killed off. While humans are likely to lose their hair, chemo given to a cat doesn’t lead to them losing their hair. Instead, it will be tired, sleeping more than usual for a day or two. 

The vet may also recommend a combination of surgery, radiation therapy, and chemotherapy. When a cat with fibrosarcoma has undergone chemo, it may survive for two or three years after diagnosis and treatment.

The vet may opt for oral medication to treat the cancer. If the cat experiences pain symptoms, the vet prescribes pain medication. Some vets are open to complementary treatments, including immunotherapy, acupuncture or nutritional therapy.

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Recovery of Fibrosarcoma in Cats

Recovery from fibrosarcoma depends on where the tumor is located, how long it has existed in the cat, and its grade. The grade is determined by the frequency of cell division within the tumor. 

Very young cats (up to one year old) are more likely to have malignant tumors. If the cat dies from fibrosarcoma, it is likely because of the recurrence of primary site tumors. A veterinary pathologist can give the vet and cat owner a prognosis which gives the cat owner a probability of recurrence of the cancer or a metastasis of the cancer to other parts of the cat’s body.

At home, pet owners need to keep the cat from scratching, biting, licking or rubbing the tumor. If an affected area becomes ulcerated, the cat’s owner needs to keep this clean. After surgery, the cat owner should report any suture loss, swelling and bleeding to the vet.

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Fibrosarcoma Average Cost

From 469 quotes ranging from $2,000 - $10,000

Average Cost

$6,000

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Fibrosarcoma Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Domestic Black Cat

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Seven Years

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Unknown severity

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0 found helpful

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Unknown severity

Has Symptoms

Swelling

My cat Lilly has developed multiple lumps above/around her left arm shoulder area (not sure if this is an injection site or possibly Fibrosarcoma, fatty tumors) it doesn't seem to hurt or no heat to it, every now and then she'll limp. She acts like her normal self (eating, drinking, playing etc.).. Im limited on money right now and just trying to get an idea of what it could be or curve into the right direction. Please an thankyou!

July 27, 2020

Owner

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Dr. Michele K. DVM

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0 Recommendations

Thank you for your question. Without seeing Lilly, unfortunately, it is difficult to say what the lumps may be. They may be benign fatty tumors, or more insidious tumors or infections. It would be best to have an appointment with a veterinarian, and they can give you a better idea as to what direction things may need to go. I hope that all goes well for her!

July 27, 2020

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Luna

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Half siamese

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12 Years

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

None

Luna is undergoing surgery at this very moment for a probable sarcoma on her back below shoulder area. if positive, highly likely per 2 vets, she will need radiation and chemotherapy and I wil need to take her to our specialty hospital for an oncologist. Unbelievable my other cat Puma ended up there for an infection that turned into heart disease and $7000 treatment. 2 months from the day he wok up vomiting and was turfed through 3 clinics, he died at home. I did everything I could for him. The reason I tell is, could Luna's stress over Puma and his death (we were both in shock) have lowered her immune system so this tumor formed just the past month?

Sept. 11, 2018

Luna's Owner

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Rocket

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domestic short-haired

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10 Years

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Mild severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

Has Symptoms

Tumor

My older, over weight male cat has a huge firm lump twords the middle of his back. Its about this size of a grapefurit. It does not seem to bother him as he still jumps and eats ect,ect. Is this something that you could help me via email? What kind of tumor do you think this may be? If it is a tumor which I'm kind of suspecting. Would this cause malnutrition?

Aug. 16, 2018

Rocket's Owner

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0 Recommendations

Without examining any animal I cannot legally make or confirm a diagnosis, however I can give an opinion and give you more information before you visit your Veterinarian (you will need to visit your Veterinarian about this). It sounds to me like an injection site sarcoma (see image in second link below), this may occur due to vaccination (most common) or any other type of injection and may form weeks or even years afterwards. The majority of injection site sarcomas are locally invasive with a small number spreading to organs; surgery is the treatment of choice. Regards Dr Callum Turner DVM https://wagwalking.com/cat/condition/injection-site-sarcoma https://vitalanimal.com/wp-content/uploads/FelineVAS300.png

Aug. 16, 2018

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Milo

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Calico

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12 Years

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Serious severity

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1 found helpful

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Serious severity

Has Symptoms

Lump

Milo has been diagnosed with fibrosarcoma in her left hind leg. She has arthritis in her left front leg and had a couple of bad stints where she cannot put any weight on her left front leg due to the arthritis. Our vet said based on the location of the tumor they would have to amputate her left hind leg. We are hesitant to do this for fear of her arthritis acting up or getting worse, and therefore would have no support on her left side. We understand that the tumor can spread and that is why amputation is needed, but would removing the tumor and not amputate the leg give Milo any relief?

Aug. 4, 2018

Milo's Owner

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1 Recommendations

Amputation is not just recommended in case of the tumour spreading but also due to location it may not be possible to remove the whole tumour with adequate margins meaning that the tumour may regrow in the same location which is what I think the problem is here based on your question. You should speak with your Veterinarian about this, but amputation would be the best overall even with the fore leg issues. Regards Dr Callum Turner DVM

Aug. 4, 2018

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Keko

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Manx

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1 Year

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Mild severity

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0 found helpful

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Mild severity

Has Symptoms

Trouble Pooping
Hopping To Get Around
Sensitive Back Legs

I think my manx cat has manx syndrome. She is a year old this month, ever since she could walk, she hopped around like a bunny, at times her anus looks like it is prolapsed, but it goes back to normal after a few days. She sometimes has trouble pooping and meows like she is in pain when she does. I don't really have the money to take her to the vet, but I will find a way. I just need to know what the Avery process is to get her diagnosed

Aug. 1, 2018

Keko's Owner

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0 Recommendations

Typically diagnosis is made by a thorough physical examination along with x-rays and possibly MRI; any affected cat should be spayed to prevent passing on the defect to offspring. You may read more about the conditions in the links below. Regards Dr Callum Turner DVM https://wagwalking.com/cat/condition/spina-bifida www.ufaw.org.uk/cats/manx-manx-syndrome

Aug. 1, 2018

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Chloe

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domestic short hair

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12 Years

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Serious severity

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1 found helpful

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Serious severity

Has Symptoms

Weight Loss

Our 12 year old female cat, Chloe was diagnosed around July 2019. At first she looked pretty good but now she's lost muscle mass or weight and her mass has grown triple in size since July. She's also lossing her hair in the center of the mass. You can see how swollen it is and how red it is. It actually looks like it is going to pop open.

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Pasha

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Persian

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2 Years

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Fair severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

Has Symptoms

None

My 2.5 yr old persian cat have small lump under his oral cavity and this lump had a fistula liked hole with some leakage...however in histology , pathologist reported a few spindle cells...they removed mass it and sent to pathology...i'm so worried...what's your opinion?

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Milo

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dsh

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7 Years

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Moderate severity

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2 found helpful

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Moderate severity

Has Symptoms

Tumor Broke Through Skin

My cat Milo was recently diagnosed with Fibrosarcoma. Milo is 7 years old and had his right rear leg amputated when he was about 8 weeks old due to a bad break from jumping off a roof. He’s been great until I noticed that at the top of his amputated leg was an open wound and bleeding. He’s been licking it. I took him to my vet and he did a fine needle aspiration. He told me Milo has Fibrosarcoma, and gave him an antibiotic shot of Convenia for infection, and Mirtazipine to stimulate his hunger. He has already lost 6 pounds. Surgery is not an option, as he would have to go into his hip. He said that Milo had maybe a month left. Do you agree with him, or should I seek a second opinion? Being retired, I do live on a limited income. Thank you.

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Hurley

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domestic short hair

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9 Years

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Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Fibrosarcomas

My sweet boy Hurley had surgery in February of this year to remove what was confirmed to be a Fibrosarcoma mass. Once the vet called me with this confirmation of what it was, the only thing she suggested was to put Hurley down. He is still behaving like normal, eating, drinking, using the litterbox, and is super affectionate with me - even after administering some anti-cancer supplements I've been giving him which he doesn't love. The Fibrosarcoma has come back in multiple places and continue to grow but he isn't showing discomfort besides trying to lick the biggest one on his back. Just this morning I noticed that the one on his back started to bleed a little bit. What can I do to help him have the best quality of life for what's left? I don't feel that it's right to put him down if he's not showing any loss of quality of life. How do I keep the tumor from bleeding? Just - any help and advice would be greatly appreciated.

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Mars

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domestic short hair

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15 Years

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Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Slight Limp
Lumps On Front Right Wrist
Taking Onsior Daily For Discomfort

Our 15 year old cat Mars has had a lump on his front right leg for over a year. We took him to our local vet then, who drained it and said the fluid inside seemed to be joint fluid. The lump filled right back up again the same day. Two days ago, I took Mars back to the vet, as his lump has grown to double the size, plus another lump is starting to develop near the original one and he is limping a bit. According to the vet, the fluid is now thicker and sticky, and the lump filled right back up again. An xray was taken, which shows that Mars' bones look solid still, but are compressed due to the pressure around them from the lumps. The vet is pretty sure this is cancer, but we have not had the xray reviewed by a radiologist. EOther than these growths and slight limp, Mars is in good health. Considering his age, we aren't sure that amputation is the best decision for Mars. If we are to allow Mars to live as long as he is comfortable, how long can we expect him to live? Are there vitamins or supplements we can give to strengthen his immunity and slow the growth of his cancer? Thank you very much!

Fibrosarcoma Average Cost

From 469 quotes ranging from $2,000 - $10,000

Average Cost

$6,000

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