fibrosarcoma in cats

What is Fibrosarcoma in Cats?

What is it?

Fibrosarcoma is a type of cancer in cats originating in the fibrous connective tissue, often in the skin or subcutaneous tissues. It is a relatively uncommon type of cancer, but it can be aggressive and may spread to other parts of the body. Therefore, prompt diagnosis and treatment by a veterinarian are essential for managing fibrosarcoma in cats and preventing further health problems.

How is it Treated?

The treatment of fibrosarcoma in cats depends on the location and extent of the tumor, as well as the cat’s overall health. Treatment may involve surgical tumor removal, radiation therapy, and chemotherapy. Supportive care and pain management may also be necessary to improve the cat’s quality of life

Breed Predispositions

It’s important to note that any cat, regardless of breed, can develop fibrosarcoma.


As a doting cat parent, Sam took pride in keeping his feline companion, Luna, happy and healthy. One day, however, he noticed a strange lump on Luna’s side that seemed to be growing rapidly. Alarmed, Sam scheduled an appointment with the vet to have Luna examined. The veterinarian performed various tests and revealed that Luna was suffering from fibrosarcoma, a type of aggressive soft tissue cancer. Devastated by the news, Sam realized that he needed to learn more about this condition to ensure that Luna received the best possible care.

Fibrosarcoma in cats is a type of sarcoma, a cancerous tumor that develops in connective tissue. They grow in connective tissues, including muscles, tendons, ligaments, fascia, fat, cartilage, bone, blood vessels, nerves, and skin. They’re most common in young adult dogs and cats. Sarcomas are malignant tumors that arise from cells called mesenchymal stem cells.

They usually occur in areas with a lot of movement, such as the shoulders, elbows, hips, stifles, hocks, tail base, and head. The tumors grow slowly over months or years and may cause lameness or pain.

They are usually found in one body part, such as the shoulder blade, elbow joint, tail base, or leg. However, in some cases, multiple sites are affected. A fibrosarcoma may grow very slowly over many months, or it may increase.

There are two types of fibrosarcoma: cutaneous and noncutaneous. Cutaneous fibrosarcomas are found mainly on the body surface, whereas noncutaneous fibrosarcoma occurs deep within the muscle mass.

  • A cutaneous fibrosarcoma is a rare form of fibrosarcomatous dermatofibroma, a benign tumor composed of spindle cells and collagen bundles. This type of tumor proliferates and tends to be aggressive, spreading quickly through the dermis and invading deeper structures.
  • Noncutaneous fibrosarcoma is a rare variant of fibrosarcoma that develops in the skeletal muscle. These tumors are slow-growing, often causing only mild discomfort.

Causes of Fibrosarcoma in Cats

Fibrosarcoma is cancer that affects cats, usually caused by exposure to certain forms of radiation. Unfortunately, the cause of this type of cancer can be challenging to pinpoint, but certain risk factors are associated with it.

First and foremost, elderly cats are at an increased risk for Fibrosarcoma due to the stress levels associated with aging feline bodies. Additionally, cats exposed to ionizing radiation from sources such as x-rays or radioactive compounds may increase their risk of developing the infectious disease.

Certain viruses may also play a role in developing Fibrosarcoma in cats; feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are two of the most highly suspected culprits. Vaccinations for these diseases have been developed to reduce the likelihood of a cat contracting them, although vaccines cannot always prevent infection or disease development.

Causes of Fibrosarcoma in Cats

Environmental pollution can also factor in illnesses like Fibrosarcoma in cats, as toxins from air and water contamination can enter their bloodstreams. This can be especially concerning if they hunt or consume small animals like lizards or frogs that may have been living near polluted ponds or yards.

Genetics can also play an essential part in health problems related to Fibrosarcoma in cats – not all breeds are equally at risk, and any predisposition due to breed should be considered when assessing an individual’s susceptibility to illness. In addition, whatever carries over through generations can increase one’s odds of becoming afflicted with this form of cancer; thus, it is vital to ensure that reputable breeders follow proper guidelines when selecting kittens for reproduction programs.

Symptoms of Fibrosarcoma in Cats

The symptoms of fibrosarcomas vary depending on where the tumor forms. They include lameness, weight loss, lethargy, pain, swelling, and difficulty eating and drinking.

Some are obvious, while others are subtle and hard to detect. Sometimes, the tumor appears like a lump under the cat’s skin masses. Other times, it looks like a mass behind the knee joint or in the shoulder area.

Diagnosis of Fibrosarcoma in Cats

If you suspect your cat has fibrosarcoma, contact your veterinarian right away. Your vet will perform a physical examination, blood tests, X-rays, ultrasound exams, biopsies, and possibly surgery to remove the tumor.

Physical Examination

A physical exam is the most crucial step in diagnosing fibrosarcoma in cats. The veterinarian should examine the cat’s mouth, eyes, ears, nose, throat, abdomen, chest, back, tail, legs, paws, skin, fur, genitals, rectum, and anus.

During this physical exam, the vet may notice any of these symptoms:

  • Abnormal gait
  • Difficulty breathing
  • Drooling
  • Excessive salivation
  • Hematoma (bloody fluid)
  • Lumps on the body
  • Painful urination
  • Sudden weight loss

If the vet notices these signs, they should perform additional tests to determine whether the cat has fibrosarcoma.

Blood Test

To diagnose fibrosarcoma, veterinarians perform a blood test called a complete blood count (CBC) and measure the amount of protein in the cat’s urine. The CBC measures red blood cells, white blood cells, platelets, and hemoglobin. The protein level indicates whether the tumor is benign or malignant.

Blood Test

To diagnose fibrosarcoma, veterinarians perform a blood test called a complete blood count (CBC) and measure the amount of protein in the cat’s urine. The CBC measures red blood cells, white blood cells, platelets, and hemoglobin. The protein level indicates whether the tumor is benign or malignant.


X-rays are a type of radiation used to detect problems inside our bodies. They often diagnose bone fractures, tumors, infections, and many other conditions. X-rays are also helpful when we need to view the body’s bones, organs, or internal structures.

When diagnosing fibrosarcoma in cats, veterinarians use x-rays to determine whether there is any evidence of cancerous cells. This helps them decide whether surgery is necessary.

Blood Test


Ultrasounds are excellent diagnostic tools for cats because they’re painless and noninvasive. They can diagnose many conditions, including tumors, cysts, abscesses, kidney stones, urinary tract infections, and heart disease.

Ultrasounds are safe for cats because they use sound waves instead of radiation. In addition, ultrasounds are not harmful to humans or pets.

Ultrasound scans are performed by placing a gel-filled tube over the cat’s abdomen. The technician moves the probe back and forth across the belly until he finds the area where the tumor is located. He may need to move the search several times to find the right spot.

Once the ultrasound scan is complete, the technician uses a computer program to create a picture of the tumor. This picture shows the location of cancer and its shape.

The veterinarian will perform a biopsy if the tumor appears malignant (cancerous). A small tissue sample will be removed from cancer and sent to a laboratory for analysis.

No further tests are needed if the tumor is benign (not cancerous). However, the vet will monitor the cat closely for any signs of recurrence.


A biopsy removes some of the tumors if the tumor is malignant. This allows the veterinarian to examine the removed tissue under a microscope. Next, the sample is sent to a laboratory where pathologists examine the cells under a microscope to determine whether the cancer is malignant (aggressive). If the tissue looks normal, the vet can rule out cancer.


Your veterinarian will recommend treatment based on the size and location of the tumor and whether it has spread to other areas of the body. If the cancer is treated effectively, there is a 50% chance your cat will survive for two years.


Surgery is typically recommended, especially when there is evidence of metastasis (spread) to lymph nodes or distant sites. High-grade tumors will metastasize in 25% of cats.

If surgery is performed, it should be done at a specialty veterinary hospital. The surgeon will remove the entire mass and any surrounding tissue. This helps ensure that the cancerous cells are completely removed.

After surgery, the patient will need to recover for several weeks. To prevent infection, the owner must keep the wound clean and dry during this period. Once the wound heals, the cat will need regular visits to monitor its progress.


Chemotherapy is sometimes used to treat advanced cases. There are two types of chemotherapy drugs: alkylating agents and antimetabolites. Alkylating agents work by damaging DNA and stopping cell growth. Antimetabolites block enzymes needed to build cells. Both drugs cause side effects, including loss of appetite, vomiting, diarrhea, hair loss, weakness, weight gain, and decreased red blood cell production.

Radiation therapy

Radiation therapy may be used to reduce the risk of recurrence.

There are two types of radiation therapy: external beam radiation therapy (EBRT) and brachytherapy. EBRT uses X-rays to kill mass tumor cells outside the body. Brachytherapy involves placing radioactive seeds inside the tumor.

External beam radiation therapy works well for tumors close to critical organs, such as the heart and lungs. However, it may not effectively treat deep tumors within the body. This is because the energy of the X-ray beams cannot penetrate deeply enough to reach cancer.

Brachytherapy is often used to treat tumors near sensitive organs, such as the brain, eyes, spinal cord, and bladder. The advantage of this treatment option is that it allows doctors to deliver a concentrated dose of radiation directly to the tumor.

Both treatments are typically administered over several weeks. Patients receive either a single fraction of radiation or multiple fractions during each session over several days.

Although no side effects are associated with radiation therapy, some pets experience temporary discomfort after treatment. Therefore, patients should be monitored closely during and following the treatment.


Immunotherapy may be used to treat these cancers. Immunotherapy involves injecting cancer cells with substances stimulating the immune system to attack them. This type of treatment is called passive immunotherapy because the body’s immune system attacks the tumor.

Passive immunotherapy works well for some types of sarcomas, including feline fibrosarcoma. But no studies are proving its effectiveness against this particular type of cancer.

Prevention of Fibrosarcoma in Cats

Cats with deep fibrosarcoma of the extremities are prone to developing osteosarcoma.

Here are seven tips to help prevent fibrosarcomas in cats.

Prevention of Fibrosarcoma in Cats
  • Be Aware of Fibrosarcoma Risk Factors

Age is one of the main risk factors for fibrosarcoma development. Older cats are more susceptible to developing these tumors.

  1. Other risk factors include breed, gender, and neuter status.
  2. Breed predisposition has been reported in Siamese, Burmese, Maine Coon, Persian, Ragdoll, Russian Blue, and domestic shorthair breeds.
  3. Gender predisposition has been observed in male cats.
  4. Neutering decreases the risk of developing fibrosarcoma.
  • Monitor Body Condition Score

Monitoring your cat’s body condition score helps identify your pet’s health changes.

  1. Body condition scoring involves assessing your cat’s coat quality, muscle tone, gait, posture, and overall attitude.
  2. A healthy cat should have a BCS between 6 and 9. Cats with a BCS below four are considered underweight, while those with a BCS above ten are considered obese.
  3. Obesity is associated with an increased risk of developing various diseases, including diabetes mellitus, hyperthyroidism, hypertension, arthritis in cats, and certain types of cancer.
  • Provide Appropriate Nutrition

Providing appropriate nutrition is essential for maintaining optimal health.

  1. Feeding commercial diets is recommended over feeding homemade diets. Commercial diets provide complete nutrients needed for proper growth and maintenance. In addition, commercial diets are formulated to meet the nutritional requirements of adult cats.
  2. Homemade diets are prepared using ingredients that are available locally. These diets may contain too much protein, carbohydrates, fats, vitamins, minerals, fiber, and water content. These diets may lack specific nutrients required for optimum health.
  • Maintain Healthy Skin

Skin conditions such as dermatitis, allergies, and seborrhea can contribute to developing fibrosarcoma lesions.

  1. Maintaining healthy skin requires regular grooming, especially for cats with thick coats. Grooming removes dead hair, dirt, debris, and external parasites from your cat’s fur. This reduces irritation and promotes healthier skin.
  2. Regular brushing prevents mats and tangles in your cat’s hair. Brushing also stimulates circulation, which improves the health of your cat’s skin.
  3. Brush your cat regularly to maintain its cleanliness and freshness.
  • Reduce Stress Levels

Stressful situations such as moving, traveling, and separation from loved ones can trigger stress responses in your cat.

  1. This can lead to behavioral problems such as aggression, anxiety, fearfulness, and excessive scratching.
  2. Reduce stress levels by giving your cat attention and affection.
  3. Ensure your cat can access safe places where they feel comfortable.
  4. Avoid exposing your cat to loud noises and sudden movements.
  • Exercise Regularly

Exercise is beneficial for your cat’s physical and emotional well-being.

It provides your cat with opportunities to socialize, play, and exercise.

  1. Physical activity keeps your cat fit and active.
  2. It also strengthens muscles and bones, which makes your cat stronger and more agile.
  3. Exercise also boosts your cat’s immune system, helping them fight infections and illnesses.
  4. Exercising your cat daily is ideal.
  5. However, exercising every 2–3 days is sufficient for maintaining fitness.
  • Manage Environmental Hazards

Environmental hazards such as heat, cold, humidity, and drafts can adversely impact your cat’s health. Heatstroke, hypothermia, and respiratory issues are the most severe environmental exposure consequences.

  1. Protect your cat from extreme temperatures by keeping her indoors during the hottest parts of the day.
  2. Keep your cat inside during winter months t frostbite and snow blindness.
  3. Use air conditioning and fans to control indoor temperature.
  4. Ensure your cat has adequate ventilation.
  5. Do not allow your cat to sleep outdoors.
  6. Cover litter boxes with plastic liners to protect against moisture damage.
  7. Clean them frequently.

Frequently Asked Questions

Disclaimer: The information provided on this veterinary website is intended for general educational purposes only and should not be considered as a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a licensed veterinarian for any concerns or questions regarding the health and well-being of your pet. This website does not claim to cover every possible situation or provide exhaustive knowledge on the subjects presented. The owners and contributors of this website are not responsible for any harm or loss that may result from the use or misuse of the information provided herein.

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