A new ferret owner brought their young, 1-year-old, male ferret in three weeks ago due to a large tumor right behind his shoulder. The mass was hard, firm, and did not move when touched. The ferret was still active, eating and fairly normal except for the large tumor. The ferret was scheduled for surgery. Unfortunately the tumor was even bigger by the day of his surgery.
During the surgery the mass was bigger and far deeper than expected. It went all the way to the ventral chest and almost into the chest cavity on the side of the body. The ferret made it through the surgery, but unfortunately it was not possible to remove the entire tumor. The removed tumor was sent out to a veterinary pathologist for analysis.
Based on the size and location, this tumor may be one of the rare injection-site sarcomas. These tumors are more common in cats. In cats, these tumors are linked to the feline leukemia vaccine, rabies vaccines and a few other injectable products. The exact cause of these tumors is still not fully understood, but a genetic problem has been found in some cats with this type of cancer. It is speculated that the inflammation from the injection eventually leads to the tumor formation. Some cat cases take months to years to develop the tumor. Ferrets can also develop this type of cancer.
I reported the first case in a ferret back in 1998 (Vaccine Injection-Site Sarcoma In A Ferret, Journal of the American Veterinary Medical Association, October 1, 1998). The article Histology And Immunohistochemistry Of Seven Ferret Vaccination-Site Fibrosarcomas in the journal Veterinary Pathology, May 2003, described seven more of these rare tumors from ferrets seen at the University of Georgia. There is also a report from Japan of this same kind of cancer in a 2½-year-old, female ferret. In the Japanese case, the tumor was over the back and caused paralysis of her rear legs.
If the pathology report on this ferret comes back as a fibrosarcoma, then chemotherapy and radiation therapy can be used. Sadly, the prognosis for this type of cancer is poor. Most cases in ferrets and cats ultimately end up being fatal.