What is Fibrosarcoma (or Injection Sarcoma)? Feline fibrosarcoma is a malignant soft tissue tumor that is very aggressive and invasive. It is often (but not always) associated with chronic inflammatory reactions at the site of an injection (vaccines, antibiotics, cortisone). This is why it is also called FISS (Feline Injection-Site Sarcoma). It presents as a hard, fixed and painless subcutaneous nodule that grows rapidly between the shoulder blades, on the side or on the legs.
When to worry? The 3-2-1 Rule
The Feline Sarcomas Task Force recommends removing and analyzing any nodule that meets even one of these conditions:
- 3 months: The lump persists for more than 3 months after an injection.
- 2 cm: The lump is larger than 2 cm in diameter.
- 1 month: The lump grows in size after 1 month from the onset. Don’t wait: if it falls within these parameters, an incisional biopsy (or removal) is needed, not a simple aspirated needle (often unreliable for sarcomas).
Why does Fibrosarcoma recur? The Octopus Effect
Fibrosarcoma is a sneaky tumor. What you see with the naked eye (the nodule) is only the central body. Under the skin, the tumor extends invisible micro-roots (like the tentacles of an octopus) that invade the surrounding muscles and fascia.
- Consequence: If the surgeon removes only the “ball”, he leaves the tentacles, and the tumor grows back more aggressively than before in a few weeks.
- Solution: Radical surgery is needed with very wide margins (often 3-5 cm of healthy tissue around).
Fibrosarcoma Cat Life Expectancy
Life expectancy in the case of fibrosarcoma depends on the depth of the tumor, the causes are:
- Subcutaneous inoculation of vaccines (post-vaccination sarcoma)
- Feline sarcoma virus called: FeSV (hybrid virus. the cat is also FeLV positive)
- Advanced age
Cats that develop fibrosarcoma have an average age of about 10 years and usually have no viral disease. It has always been thought that only vaccines, injected under the skin, could cause fibrosarcoma to develop. Today the hypothesis that other injected substances can also give rise to sarcomas is gaining ground, because it has been seen that the inoculation areas (interscapular, cervical, femoral) are the main sites of inflammatory reactions;
Cat fibrosarcoma causes and why it develops
- There is a “certain” genetic predisposition
- Cats have an abnormal response to inflammation
INFLAMMATION OF THE SKIN PROMOTES THE FORMATION OF FELINE FIBROSARCOMA FIRST HYPOTHESIS
In the vaccine (live modified) there is a substance called aluminum hydroxide (adjuvant) that allows the vaccine to be released slowly, thus managing to activate an immune response for a longer time. Unfortunately, the toxicity of the adjuvant and the reactivity of the immune system promote local inflammation in the vaccination area.
This is only a first hypothesis, BECAUSE the adjuvants used are different as are the pharmaceutical companies that produce the vaccines
STUDIES HIGHLIGHT OTHER CAUSES
Some cats have developed inflammation, such as that which precedes cancer, with injections of saline solution or with injections that contained other substances such as corticosteroids, antibiotics.
SECOND HYPOTHESIS
The inflammation is caused by the cat’s hair, or impurities present on the skin, at the time the injection is given.
THIRD HYPOTHESIS A genetic component is suspected
What can we do to reduce the risk of cat fibrosarcoma?
- Ask your vet to inoculate the thigh or tail area, as they can be amputated and save your cat’s life
- Ask your vet to use very fine needles to avoid “skin trauma” while reducing the chance that the injection will carry hair and dirt with you.
Where possible, it is preferable to administer a drug orally, the active ingredient enters the circulation in about an hour, give injections only in case of urgency and need.
Fibrosarcoma in cats can develop after many years
I recommend reading THIS article on vaccinations and antibody titration in cats. According to the WSAVA 2015 guidelines for vaccinations in dogs and cats, it is no longer recommended to vaccinate every year.
ONLY CONSCIOUS AND TARGETED VACCINATIONS
THE CLINICAL ASPECTS AND SYMPTOMS OF FIBROSARCOMA IN CATS
- Presence of a subcutaneous nodule, which persists beyond three months after vaccination
- Presence of multiple lesions with a granular appearance, “cord-like”
Cat fibrosarcoma how long it recurs
- To date, surgical therapy remains the only solution
- The surgery must be performed by a veterinary oncologist
- It may be necessary to reach up to 5 cm beyond the fibrosarcoma and remove adjacent tissues and bones
The recurrence of a fibrosarcoma in a cat is almost always certain even if it depends a lot on its location, on the often recurrent back and the times vary from a month to a year, the times depend on the degree of malignancy of the neoplasm, so it is important to think about how to support our cat during this difficult phase, how to manage pain, post-operative and delay the onset of recurrences by evaluating integrated natural therapies.
Cat fibrosarcoma alternative cures and natural cures
Discover 30 natural remedies for cancer to start supporting your pet’s immune system right away
Beyond Surgery: Electrochemotherapy and Support
Because recurrence is common, surgery alone is often not enough.
Immune Support: Medicinal mushrooms (Maitake, Shiitake) and Omega-3 to reduce the chronic inflammation that fuels sarcoma.
Electrochemotherapy (ECT): An innovative technique that uses electrical impulses to make the chemotherapy drug (bleomycin) penetrate directly into the tumor cells remaining at the surgical site. Very effective for “sterilizing” margins.
Prevention (Where to vaccinate?): Ask your vet to vaccinate on your tail or lower leg. In the case of cancer, amputation is curative, while a tumor between the shoulder blades is difficult to operate radically.
Frequently Asked Questions about Injection Sarcoma
How long after the vaccine does the tumor appear?
There is no fixed rule. It can appear after a few months, but also after years (up to 10 years) from the injection. This is why it is difficult to link it to a specific event.
Does cat fibrosarcoma lead to death?
If left untreated, yes, because it ulcers and invades vital tissues. However, it rarely metastasizes to the lungs (only in 20% of late cases). The real danger is local recidivism that becomes inoperable.
What to do if I feel a ball after the vaccine?
It is normal to feel a small lump (granuloma) immediately after the vaccine. Monitor it. If after 1 month it is still there or growing, apply the 3-2-1 rule immediately and run to the vet.
DISCLAIMER: THE CONTENTS ARE FOR INFORMATIONAL PURPOSES ONLY AND UNDER NO CIRCUMSTANCES CAN THEY CONSTITUTE A PRESCRIPTION FOR TREATMENT OR REPLACE A SPECIALIST VISIT OR DIRECT RELATIONSHIP WITH YOUR VETERINARIAN/DOCTOR.
