The United States Department of Agriculture (USDA) has approved Carravet® Acemannan Immunostimulant for use in the treatment of fibrosarcomas in dogs and cats. Fibrosarcoma is a malignant tumor of connective tissue such as bone, muscle and cartilage. Surgical removal of fibrosarcoma is difficult because of the way it grows. It sends out finger-like projections that attach to surrounding tissue. Because the tumor is so spread out, it can be difficult to completely remove. Subsequently, the tumor recurs and leads to additional surgeries, possible amputation of affected limbs and/or death. These tumors do not respond well to chemotherapy.

The incidence of fibrosarcomas is on the rise, especially in cats. These tumors have been associated with reactions at vaccination sites.

Carravet® Acemannan Immunostimulant manufactured by Carrington Laboratories, Inc., is a natural product refined from the aloe plant. It works by stimulating the immune system to encapsulate, or 'wrap up' the tumor. Following the treatment, the tumor may have clearly defined edges and it becomes easier to successfully remove the entire tumor.

Acemannan is most effective when combined with surgery and radiation. The product is injected into the animal and into the tumor itself.

Comments from our Veterinary Staff:

New methods to more successfully treat cancers, especially difficult ones such as fibrosarcoma, are very welcome.

A national Vaccine-Associated Feline Sarcoma Task Force composed of veterinarians, researchers, and vaccine manufacturers are working to determine the exact cause of these tumors and how they can be prevented and treated. Possible explanations for the tumors include abnormal reactions to the adjuvant in vaccines, genetic predisposition, and infections with another virus.

The possible risk of vaccine-associated fibrosarcomas has led to a reevaluation of vaccination protocols. This is why it is recommended that cats without potential exposure to FeLV may not need vaccination against that disease. In cats with potential exposure, the risk of FeLV infection is greater than the risk of developing a sarcoma so vaccination is advised.

Generally, the FeLV vaccine is now given in the left rear leg, in an area distinct from where other vaccinations are given. If a tumor would develop, knowing which vaccine was given where will help us determine with which vaccine the tumor is associated. Also, if a tumor would develop, amputation of the leg would, in many cases, be curative. Cats do incredibly well on three legs, and many owners prefer this to having their cat succumb to a tumor.

A small, painless swelling sometimes develops at the site of a recent vaccination. This should disappear in several weeks. If it persists, however, it could mean it is developing into a sarcoma and should be checked by your veterinarian.

The Vaccine-Associated Feline Sarcoma Task Force advises the warning signs for a vaccine-related fibrosarcoma are:

• A lump persists for more than three months after vaccination
• It is larger than two centimeters in diameter (2.5 centimeters = 1 inch).
• One month after vaccination it is still increasing in size.

If you have any concern regarding a lump at a vaccination site, do not hesitate to contact your veterinarian.