Soft Tissue Sarcomas In Dogs

Soft tissue sarcomas are tumors that develop in the soft tissues of a dog’s body, including the muscles or the connective tissues. Soft tissue sarcomas in dogs are not painful, and the most notable symptoms are the size and growth of the tumor beneath the skin. They are commonly found on the legs, chest or abdominal area.

Types Of Canine Sarcomas

There are various types of sarcomas in dogs that can develop on or around the soft tissues. While identifying the type of sarcoma in dogs is valuable, when it comes to soft tissue sarcomas, it is more important for you and your veterinarian to monitor the size and growth of the mass. The rate of growth of the sarcoma can have an impact on its ability to metastasize — or spread — throughout your pet’s body. Dogs are at risk of developing canine soft tissue sarcoma around the time they reach the age of 10though they can be seen at any age. It’s worth noting that there is no specific breed that is more at risk of developing these tumors, nor is a particular sex at a higher risk. Some types of sarcomas include fibrosarcomas, nerve sheath tumors, schwannomas and hemangiopericytomas. Liposarcomas and rhabdomyosarcomas are more aggressive forms of sarcomas. Approximately 10-20% of soft tissue sarcomas will metastasize and spread throughout the body. In most cases, when this tumor does metastasize, it spreads to your dog’s lungs or lymph nodes.

Clinical Signs To Look For In Your Pet

The clinical signs of sarcomas are not always obvious and are most often discovered during a routine veterinary exam. These are a few clinical signs that you can look for at home, in order to ensure that your pet gets the treatment he or she needs as soon as possible:

• Mass: The most common symptom of a soft tissue sarcoma is a mass that has formed near the soft tissues and underneath the skin. The lump or bump can vary in size, so it may not necessarily be visible to the naked eye. You may notice a mass as you are bathing your pet, brushing your dog’s coat or simply cuddling with him or her. Your veterinarian may also discover a mass during a routine exam. For most dogs, the soft tissue sarcomas are not painful.
• Limping or Lameness: In some cases, if the soft tissue sarcoma develops underneath the dog’s legs, then the growth and development of the mass could cause your dog to limp or have difficulty walking. Again, the sarcoma itself is likely not painful, but the size of the tumor may prevent your dog from being able to walk normally.

Diagnosis & Staging For Soft Tissue Sarcomas In Dogs

If you or your veterinarian discovers a soft tissue sarcoma on your dog, there are several steps that need to be taken. Your vet will likely start the diagnostic process by running routine blood work on your dog.   Your vet may take three-view chest X-rays to see if the tumor has spread to the lungs. An important step is typically to aspirate — or withdraw cells— from the mass in order to verify that it is in fact a soft tissue sarcoma. Finally, the mass may undergo surgical biopsy to identify which type of soft tissue sarcoma it is. ((Not for print, just your understanding: some vets will aspirate the m ass first, wait for the results, before doing the rest of the work up))

Soft Tissue Sarcoma Treatment Options

Once the veterinarian has completed the diagnostic screening, you should have a better understanding of your pet’s treatment options. If the tumor has not metastasized, these are the treatment options that may be available for your dog:

• Surgery: Surgery is often the first treatment that veterinarians consider for soft tissue sarcomas. If there is a margin of at around 3 cm, the tumor can often be removed. With these margins, the surgery is typically successful at curing the cancer about 90% of the time. If there are smaller margins, the tumors will likely grow again within 6 or 8 months.
• Chemotherapy: If a tumor cannot fully be removed with surgery, chemotherapy can be used to help slow the tumor’s growth and development. Chemotherapy is not a cure, but rather a way to prolong the life of your dog.
• Stereotactic Radiation: Stereotactic Radiation is one of the most innovative treatment options available for dogs with soft tissue sarcoma. At PetCure Oncology, our team is qualified to provide this treatment option, which is designed to maximize damage to the tumor without harming the other tissues and organs in the surrounding area. Stereotactic Radiation can be administered in fewer treatments and has fewer side effects than chemotherapy. SRS is a form of radiation therapy in which a patient may only need 1-3 radiation treatments, minimizing side effects.  This novel form of RT is showing much promise for treatment of these tumors
• Conventional Fractionated Radiation Therapy (CFRT) is a form of RT using a lower dose per treatment than SRS.  As such, a patient may need 19-21 treatments. CFRT can cure 76% of incompletely resected soft tissue sarcomas.  

Update: Stereotactic radiation (SRS/SRT) can now be delivered safely and effectively to cancer patients who have undergone surgery to remove a tumor but are still found to have residual cancer. This advancement was tested through a PetCure clinical trial conducted between May 2017 and March 2019 with findings published in the July 2023 edition of JAVMA, providing new hope for many dogs and cats that are in need of additional cancer care after undergoing tumor-removal surgery. This cutting-edge technology allows for the insertion of a liquid fiducial marker at the tumor site, either during or after surgery, providing a necessary target for radiation therapy treatment planning.  This innovative approach offers new hope for our furry companions in their fight against cancers like soft tissue sarcoma, mast cell tumors and adenocarcinoma like those found in anal sac adenocarcinoma.

Prognosis For Dogs Diagnosed With Soft Tissue Sarcoma

When soft tissue sarcomas in dogs are treated with surgery, chemotherapy or Stereotactic Radiation, the pet’s life expectancy is often prolonged and the prognosis is favorable. However, if the tumor has metastasized, then the cancer is likely terminal. The amount of time that your dog has left will depend on the type of sarcoma that has developed and its rate of growth. Find a PetCure Oncology Location Near You If your dog has been diagnosed with soft tissue sarcoma, it’s important to know that you have options. Your dog deserves the best possible care, and the experts at PetCure Oncology can provide all the treatment options that your beloved pet requires. We believe that dogs deserve the same sort of care and respect as human patients, and we specialize in providing this unique form of support. For more information about PetCure Oncology and our innovative treatment options, find a location near you today.

RELATED: Pet Hero: Brownie the Labrador Retriever Mix, Pet Hero: Cancer Didn’t Stop Kita The Adventurous Pup, Soft Tissue Sarcomas In Cats, Case Study: Maxillary Sarcoma