* Petmoo is reader-supported. When you buy products via links on our site, we may earn an affiliate commission at no cost to you.

Fibrosarcoma In Dogs: Causes, Types & Treatment

Fibrosarcoma In Dogs

Canine Fibrosarcoma (FSAs) is malignant and highly cellular; infiltrating neoplasms in dogs especially develop from the uncontrolled proliferation of cells called fibroblasts.

Fibroblasts are the hyperchromatic, mitotically active, fibrous cellular material of the connective tissue in the body. The spindle-shaped cells found in the interstitial spaces of organs secrete collagen proteins that support, bind, separate, or connect other organs and tissues. Fibrosarcomas occur most often in the connective tissue of the skin, bone, and their adjacent tissues.

Canine fibrosarcomas are highly aggressive and they typically arise from the skin, the fat underneath the skin, and the adjacent tissues. The most prevalent locations are the skull, jaw trunk, and extremities. Fibrosarcomas are considered only locally invasive, however, about ten percent of them will metastasize to other organs.

These tumors are hard to categorize and are frequently considered as a group due to the similarity in their presentation. Consequently, when this category of tumors is discussed you may hear several different names besides fibrosarcoma. Some of the fibrosarcoma-type tumors are Peripheral nerve sheath tumors, Neurofibromas, schwannomas, hemangiopericytomas, and spindle cell tumors.

Although the exact cause is unidentified, genetic susceptibility and environmental factors are considered to play an important role. Sadly, the fibrosarcoma prognosis is considered to be poor. Regardless of aggressive oncological and surgical intervention, over 75% of tumors relapse within the first year.

Symptoms Of Fibrosarcoma

The fibrosarcoma symptoms vary depending on the location.

  • When skin is affected- Swollen, nodular, firm bump or lump on or under the skin, Bleeding or ulcerated lumps.
  • If the leg is affected - Lameness, difficulty getting up or lying down, Paralysis, Arthritic type symptoms, Lethargy, etc.
  • If the nasal cavity is affected - Excessive tearing, mucus discharge, nose bleeding, snuffling and snoring sounds, pawing at the muzzle, and sneezing.

Other systemic signs

  • Swelling/edema of the face and extremities
  • Loss of appetite/ Weight loss
  • Polydypsia/polyuria
  • Breathing or digestive issues

Treatment Options For Fibrosarcoma

Survival rate and prognosis are dependent on the grade and stage of cancer, and how promptly treatment is given.

Fibrosarcoma getting completely cured is relay uncommon, but treatment can make your dog feel better, with the least side effects.

Surgical options such as amputation, radiation, chemotherapy, or a combination of these modalities may be tried.

Steroid treatment

(Prednisolone): 2 mg/kg (or 40 mg/m2) PO daily.

By itself, the antitumor dosage of prednisone increases average survival times to 1 to 3 months, but it is not beneficial in all cases. Sometimes, it makes subsequent chemotherapy treatment less successful.

Chemotherapy:Chemotherapy is found to be less effective. Daunorubicin, vincristine, vinblastine, dactinomycin, colchicine, etoposide, and mitoxantrone is commonly used.

Radiotherapy: This may be used to shrink cancerous cells prior to surgery or used post-op to reduce the duration of the resulting remission.

Home Remedies For Fibrosarcoma

Fibrosarcoma cannot be completely cured even with medical management. Discuss about home treatments with your vet to ensure they’re won’t mess with other medications.

Prevention Of Fibrosarcoma

Prevention is not possible for canine Fibrosarcoma as the causes in dogs is varied. Treatment and survival rates vary depending on the grade and stage of cancer.

Good overall health and early detection are the only ways to prevent lymphoma.

Check your dog on a regular basis and consult your veterinarian immediately if you find any odd lumps or lesions.

Affected Breeds Of Fibrosarcoma

Gordon Setter, Irish Wolfhound, Brittany Spaniel, Golden Retriever, Doberman Pinscher, Basset Hound, German Shepherd, Rottweiler, Scottish Terrier

Additional Facts For Fibrosarcoma

1. Causes:

  • Hereditary
  • Radiation or electromagnetic fields exposure or living near waste incinerators.
  • Certain viral infections (Retroviruses).
  • Exposure to carcinogens or toxic chemicals (benzene and phenylbutazone).
  • Exposure to herbicides, pesticides, and insecticides.

2. Types:

Primary fibrosarcoma: They originate in the connective tissue itself and spread to other parts of the body. Primary bone FSA has a propensity to metastasize to skin, lymph nodes, and pericardium, rather than lungs.

Secondary fibrosarcoma: That arises from a different organ or tissue and metastasizes to the connective tissues.

3. Stages:

  • Stage 1: < 5 cm and has not spread to the lymph nodes or to other sites
  • Stage 2: >5 cm and has not spread to other sites
  • Stage 3: Tumour can be any size but has not spread to other sites
  • Stage 3B: Tumour has spread to lymph nodes
  • Stage 4: Tumor is of any size. Lymphs may or may not be involved but it has spread to distant sites

4. Mortality: With the increase in stages, the mortality rate of dogs proportionately increases.

Usually, the life expectancy in dogs without treatment is 1-2 months. With chemotherapy protocols, this can be increased to 12 months for about 80% – 90% of dogs.

5. Diagnosis:

  • Routine hematology, blood smears
  • Immunophenotyping
  • Clonality assessment by polymerase chain reaction (PCR) testing
  • Abdominal ultrasound
  • Fine-needle aspirate and cytological examination via microscopy

6. Prognosis:

Fibrosarcoma activity is complicated and depends on many factors. In general, the cancer is staged from 1 -to 4; with stage 1 is less destructive than stage 4 Fibrosarcoma.

Unfortunately, most Fibrosarcomas are rapidly progressive and high-grade. Initially there will be enlarged lymph nodes and no clinical signs of illness, If left untreated, most dogs reach terminal stages 1-2 months from the presentation.

When To See A Vet

Contact your vet right away, if you notice any of the following:

  • Swollen, nodular, firm bump, or ulcerated lumps
  • Swelling/edema of the face and extremities
  • Polyuria/ Polydypsia

Food Suggestions For Fibrosarcoma

The ratio would be:

35 to 50 percent protein + less than 25 percent carbs + 25 to 35 percent fat (including omega-3 fatty acids and arginine).

  • Low fat, high protein foods- White-Fleshed Fish, Skinless, White-Meat Poultry, Beans, Peas, and Lentils.
  • Protein- chicken breasts, turkey breasts, liver, ½ Cup Raw Salmon (or cooked).
  • Lean meats, such as chicken breast, sirloin, or pork.
  • DHA-mackerel, salmon, herring, sardines, and caviar.
  • Antioxidants- Blueberries, blackberries, Steamed broccoli, spinach, cooked yellow squash, kale, and green beans.
  • Fats- Chicken/turkey fat or beef tallow.


As with any cancer, proper and earlier diagnosis, as well as aggressive treatments, gives more successful outcomes.

Dogs with Fibrosarcoma often survive for 1-2 months without chemotherapy, but with treatment, the prognosis is even better. Dogs can have an improved quality of life for a period of time with proper treatment.

dog care
dog health
dog breeds
dog food
dog training
dog insurance
Petmoo Tools
Essential Tools for Pet Owners
Top Rated Services In Your Neighborhood