Soft Tissue Sarcoma in Cats - Types and Treatment



See files for Cats
Feline sarcoma is a type of cancer which affects mesenchymal cells of various tissues. This means it can affect tissues such as bone and cartilage, but it is more common in the soft tissues such as fat and muscle. These sarcomas most commonly present as tumors and it is normally used to describe malignant cancers, although they can be benign. With malignant sarcoma, there is the risk of metastasis which can spread to healthy tissues and complicate possible treatment. This is why surgical removal is often the most common treatment, removing cancerous tissue with a wide margin to avoid reoccurrence. AnimalWised explains more about the types and treatment of soft tissue sarcoma in cats.
What is a soft tissues sarcoma in cats?
Mesenchymal cells are embryonic cells which develop into various tissues in the body. Along with epithelium cells, they give rise to the majority of the body's organs during the embryonic stages. When mesenchymal cells become cancerous, they can develop into a tumor of various connective tissues known as a sarcoma. These can be of hard tissues such as the bones and teeth, but they are most commonly present in soft tissues.
Soft tissue sarcoma is usually malignant, although it is possible for it to be benign. The tissues it most commonly affects are those of the muscle, fat, fibrous tissues or blood vessels. These cancer cells of the connective tissues begin to multiply in an uncontrolled and abnormal manner. When this happens, they most often develop as a form of tumor. If affecting tissues such as muscles or fat, it becomes a solid and palpable mass.
Feline sarcomas are slow-growing tumors, but they can easily invade deeper layers of adjacent tissue. They can also metastasize to other parts of the body. The most common areas where soft tissue sarcomas in cats originate are the following:
- Legs
- Trunk
- Injection sites
Although these are the areas of the body where they most commonly appear, there are different types of sarcoma. These are classified according to the tissues in which they develop.
Types of soft tissue sarcoma in cats
Feline sarcoma can originate in connective tissues in different locations. These leads to the following different types of sarcoma in cats which can vary in terms of frequency and aggressiveness:
- Fibrosarcoma: this is thee most common type of sarcoma in cats. It develops from fibrous tissue beneath the skin and appears as a firm lump on the neck, legs or back. It is locally invasive and has a low rate of metastasis, making it more treatable than some other forms of feline sarcoma.
- Injection-associated sarcoma: this is a subtype of fibrosarcoma that appears in areas where the cat has received subcutaneous injections such as those used for vaccine administration microchip implantation. It is also very locally invasive can appear weeks or months after the injection.
- Hemangiosarcoma: a sarcoma that originates in the blood vessels of the skin and internal organs such as the liver or spleen. It is a very aggressive type of sarcoma, often causing rapid metastasis.
- Osteosarcoma: a bone sarcoma that is rare in cats. When it develops, it usually occurs in the jaw or axial skeleton. It is less aggressive and has a lower metastasis rate than this same type of sarcoma in dogs.
- Liposarcoma: a sarcoma originating in fatty tissue. It is very rare in felines, but it is usually located in the abdomen, limbs or trunk when it does occur.
- Chondrosarcoma: a sarcoma originating in cartilage, primarily in the nasal cavity or bones. It is rare in cats and spreads less widely than other types of feline sarcomas.
- Neurofibrosarcoma or malignant schwannoma: a rare type of sarcoma that affects peripheral nerve sheaths, causing pain, lameness or local paralysis.
- Rhabdomyosarcoma: a sarcoma originating in striated muscle. It is highly invasive and serious, although it is fortunately quite rare in cats.
Learn more specific information about the causes, symptoms and treatment of fibrosarcoma in cats.
Causes of sarcoma in cats
The exact causes of sarcomas in cats are poorly understood. We do know there are certain risk factors which can influence their development, often in combination with each other. For example, there is a genetic factor which can contribute to sarcoma development, meaning some cats may be predisposed to them.
We have already mentioned that injection-site sarcomas can occur. This is because localized inflammation can occur as a result of an overly strong immune response, something which itself can be associated with a genetic influence. In these cases, the type and frequency of the injections can also influence their development. It is very important to know that these instances are very rare and their risk does not outweigh the benefit of vaccinations.
Other factors which can influence the development of soft tissue sarcoma in cats include trauma, chronic inflammatory processes and exposure to radiation. All of these can be affected by genetic predisposition.
Symptoms of soft tissue sarcoma in cats
How a sarcoma presents depends on various factors, especially the location and severity of the cancer. The main sign of any type of sarcoma is the presence of a hard and firm lump. Feline sarcomas most commonly present on the trunk, legs, back or neck, as well as common injection sites such as between the shoulder blades.
When the sarcoma initially develops, the tumor does not usually cause pain. As it grows, invades nearby tissues or metastasizes, the symptoms can become more pronounced. The health of the cat will be seriously affected and the cancer will be fatal if left untreated. Some of the symptoms of sarcoma in cats include the following:
- Ulceration or skin changes
- Bleeding
- Lethargy
- Loss of appetite
- Weight loss
- Limping or motor control changes
- Breathing difficulty
- Vomiting
The cancer can also lower a cat's immune system significantly. This puts them at greater risk of secondary diseases, meaning the sarcoma can kill them indirectly.
Where a sarcoma is located can affect the symptoms which present. Learn more about one such location with our article on nasal cancer in cats.
Cat sarcoma in cats be cured?
Yes, feline sarcoma can be treated and cured in some cases. The efficacy of treatment will depend on its location and severity. Due to the tumor's aggressive nature and its advanced stage at the time of diagnosis, some treatment may not provide a cure. Sarcoma is generally curable when detected early. This is further improved if surgical removal with wide margins is possible and there are no distant metastases.
Soft tissues sarcoma in cats treatment
Whenever the sarcoma is treatable, surgical removal is the first and best option for treating this type of feline cancer. This removal requires wide margins due to the tumor's potential to invade deeper surrounding layers. This helps to prevent the growth of tumor tissue that could cause recurrence. In the most aggressive cases, complex surgeries or amputations are sometimes required.
When the tumor cannot be completely removed, radiation therapy may be useful. Even with successful surgery, radiotherapy may be implemented to better prevent recurrence. Although less effective, chemotherapy can help in cases of metastasis. In more advanced cases or in inoperable tumors, palliative care is indicated to control pain and improve quality of life.
Since the surgery required for sarcoma is usually invasive, they will need a general anesthetic. Our related article explains how long anesthesia lasts in cats and risk factors are involved.

Life expectancy of a cat with soft tissue sarcoma
The life expectancy of a cat with soft tissue sarcoma depends greatly on the type of sarcoma, as well as its size, location and extension. If the tumor can be removed with wide margins, the life expectancy is longer than in cats with sarcomas that have metastasized or invaded very deeply into inoperable structures. Generally speaking, the life expectancy of a cat with sarcoma varies depending on the severity of the disease:
- Cats with localized sarcomas that have undergone surgery with wide margins can have a life expectancy of up to 5 years.
- Localized sarcomas with narrow surgical margins have a greater a risk of tumor recurrence, meaning their life expectancy can be anywhere between 6 months to 2 years.
- Cats with sarcoma that has metastasized can have a life expectancy of 2 to 6 months.
- In untreated cats with advanced sarcoma, the life expectancy can be as low as a few weeks.
You can learn more about the symptoms and treatment expected during the stages of breast cancer in cats with our related guide.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.
If you want to read similar articles to Soft Tissue Sarcoma in Cats - Types and Treatment, we recommend you visit our Skin problems category.