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Dog Vaccine-Site Sarcomas

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Dog Vaccine-Site Sarcomas

Vaccine-site sarcomas can be called many different things. They are known as injection-site sarcomas, vaccine-associated fibrosarcomas et al. These are tumors that are believed to be caused by vaccinations. They are very rare but can happen if your dog has immune system reactions to the vaccine.

Sarcomas are malignant tumors that are composed of connective tissue cells. They are quick to develop and are subject to metastasis.

They were initially identified in the 1980's when vaccines began to be developed differently than in the past. The live vaccines were discontinued and the new vaccines were developed with dead viruses. Aluminum was added to the vaccines and there are some scientists that believe that this is cause.

These sarcomas do not always appear immediately after your dog is vaccinated. They can appear as long as 9 years after the initial inoculation. While they appear to be localized, there are branches that can spread into the healthy tissue that surround the site. When surgery is performed to remove the tumor the fingers/branches can stay and contribute to metastasis. It is estimated that over half of the sarcomas that are removed will recur within half a year.

There are several different types of vaccine-site sarcomas. They can be fibrosarcoma, Dog Osteosarcoma - OSA, Dog Myxosarcoma, Dog Liposarcoma and other types as well. The name is indicative of the area in which the tumor originates.

Signs and Symptoms

As you run your hand over your dog, you need to be aware of any abnormal lumps under the skin in the various areas that your dog has had their vaccinations. The usual places are behind the neck and the back of their legs.


If you notice a mass, nodule or some swelling under the skin, take it seriously. Schedule an appointment with your veterinarian to have it examined. This is especially true if the lump remains for several months. If the swelling is noticed soon after the vaccination, get your dog to your vet as quickly as possible. Your vet will perform a physical examination to feel the lump and evaluate it. This will be followed by fine needle aspirate. This can tell your vet the type of tumor that has developed. Although this process is good for staging, it is not particularly conclusive for identifying the type of tumor. Some tumors do not shed cells that can be obtained with a needle aspiration.

After the needle aspiration your veterinarian will perform a biopsy. This will remove a small portion of the mass to examine under a microscope.

X-rays of the surrounding areas will be done in an effort to determine whether metastasis has occurred.

Treatment Options

These are very aggressive tumors and there will most likely be more than one course of treatment necessary. Your vet will perform surgery to remove the obvious mass and this will be followed by Dog Radiation Therapy and Dog Cancer Chemotherapy.

Home Care

Observe your dog. Be especially aware of the area that the mass was removed. You will be making routine visits to your veterinarian so that he or she can keep a close check on your dog's rehabilitation. Prevention

The only prevention is the elimination of vaccinations. This is not an option and is illegal in some states. It is therefore important to continue your scheduled vaccinations. There are some vaccines that are given every three years instead of every year. This may be your preference.

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