Canine Injection-Site Sarcoma: So Rare, Your Vet Won't Believe You

Duke is a young male boxer dog who proved his veterinarian wrong when he was diagnosed with a malignant injection-site sarcoma (ISS). Duke was born in a February litter of AKC registered boxer puppies in 2004. He received his first Rabies vaccination upon reaching the age of three months, as most dogs do. The events of this particular vaccination were not particularly memorable, although Duke's human "Mom" would recall later that she was apalled at how unsanitary the the veterinarian's hands seemed to be, and the fact that he did not wear any protective gloves while administering the injection.

Duke rebounded from the sharp sting of the vaccination needle and continued to play, as puppies love to do. He didn't seem to notice the small lump which appeared within a couple of days of the vaccination and which continued to linger for several weeks. Duke's family noticed though and returned to the Vet's office, where the lump was explained away as a possible allergic reaction to the shot, or as a small buildup of tissue under the skin that was considered a normal to an injection.

As the months passed, the lump continued to worry Duke's family; it was subcutaneous (under the skin) and seemed to be growing. Duke made a few more trips to the vet for this and that, and each trip, his human family would ask the vet to look at his lump again. Each time they were told not to worry about it, that "Boxers are notorious for tumor growths," and that "The odds of a cancerous tumor in a puppy this young are negligible."

By October, the lump was the size of a golf ball and was both visible and concerning to everyone. The veterinarian seemed somewhat interested in this growth and continued to advise Duke's family to watch the tumor for any additional changes. By early November, Duke's family had had enough with the waiting and demanded the lump be excised and biopsied. When the biopsy results came back from the state laboratory, the vet could not and would not believe them--and in fact questioned the state lab's diagnosis: "Canine Injection Site Sarcoma - Malignant."

Duke and his family have since moved and visited several other veterinarians, all of which exclaim how rare injection site sarcoma is in canines. They are all quick to explain that cats with this form of cancerous growth are quite common, but none seem eager to be the first to officially recognize or document this particular canine occurence. Duke's family wants dog lovers everywhere to realize that just because something is "rare" it should not be discounted as a possible diagnosis.

Failure to consider the rare possibilities can result in the unnecessary loss of your pet. In Duke's case, he was saved by his "Mom's" determination and access to the Internet, where she found information regarding Injection Site Sarcoma--and while the symptoms given were those experienced by cats, the information was still applicable to dogs, and made the difference in saving Duke's life by stopping the spread of his cancerous growth to other healthy tissue in his body. Currently, injection-site sarcomas are recognized by the medical community as an affliction specific to cats. Tell that to Duke, and he'll wag his tail because his family wouldn't take "No" for an answer when it came to his health.

In an effort to make information on canine injection site sarcoma less of a mystery and more a thing of history, Duke's family offers you the following helpful information:

What You Need To Know About Injection Site Sarcoma

Sarcoma: A sarcoma is a malignant tumor composed of cells derived from connective tissue. These tumors develop quickly and can spread or metastasize throughout the body. Sarcoma are not typically responsive to treatment, and unless surgically removed (excised), can result in serious illness and ultimately death. A recurrence sarcomas in the affected animal is common after excision.

Injection-site sarcoma: An injection-site sarcoma is a tumor that is usually induced by the injection of a vaccine. Post-vaccination sarcomas are considered a consequence of an overzealous inflammatory or immune system reaction to the vaccine.

Vaccine: A vaccine is a solution which includes microorganisms that have been rendered harmless. The United States Department of Agriculture (USDA) has directed vaccine manufacturers to produce vaccines comprised of nonviable (dead) microorganisms. Because of this, most vaccines now include aluminum. The aluminum component of the vaccines is the suspected catalyst of the development of post-vaccinal sarcomas.

Vaccination: A vaccination is the administration of a vaccine for the purpose of inducing the development of an immunity in the body to the microorganism in the vaccine. Vaccinations should be administered in a sanitary manner. The injection site should be cleaned and properly prepared, and the person administering the injection should be wearing a fresh pair of disposable gloves, to protect the injection site from any debris.

What to watch for: Watch for a firm, painless swelling (like a lump) under the skin, in the region of the body in which your pet received a vaccination. Regularly checking for lumps with your hands will help you catch such a growth early, and allow you to monitor it for changes.

What to do if you find a lump: Take your pet to a Veterinarian as soon as possible. Request an excision, or at least a biopsy. A swelling that develops at the site of a previous vaccination or other injection should be considered malignant until proven otherwise. If your vet suggests fine needle aspiration, decline and request a biopsy or excision. Fine needle aspiration and cytological examination are not reliable for the diagnosis of injection-site sarcoma, as this type of tumor does not readily shed cells during routine needle aspiration.

What not to do if you find a lump: Do not settle for less than adequate health care for your pet. Do not take "No" for an answer from your vet, regarding the diagnosis of a possibly cancerous and fatal growth on your pet. Demand the care for your pet, or find another veterinarian and try again.

Duke's actual biopsy results: "INJECTION SITE SARCOMA, CANINE: This is based on the age, location, and morphology of the tissue reaction."

Histophathology:

". . .A large central mass of amorphous and granular, eosinophilic and basophilic material of probably injection origin, with necrotic debris. This is surrounded by a thin layer of fibroblasts and active macrophages with an outer thin fibrous capsule (necrotic granuloma). Most of the remainder of the two thin tissues consist of multiple fronds of very active and dense fibroblastic proliferation with extensive, multifocal mineralization and many tumor multinucleated giant cells. Occasional lymphoid nodules are present. There are several empty pockets in the fatty, gollagenous, and tumor stroma that are lined by a compressed layer of granulation tissue, with the more anaplastic fibroblasts comprising the majority of the stroma away from these empty senters. This is suggestive of small local seromas with apparent malignant transformation of their granulation tissue wall. There are essentially no neutrophils (no bacterial infection)."

Long live The Duke!