Immunotherapy is the use of vaccines to treat cancer, not prevent it. The other vaccinations your pet receives help to prevent disease. The only readily available vaccine for cancer is the melanoma vaccine. This again is used to treat patients that already have melanoma. The goal of these vaccines are to prevent or delay disease progression and metastasis. Vaccine treatments tend to be well tolerated by patients and has a moderate (30%) response rate in melanoma in dogs. Other vaccines for other diseases may be available, but are only experimentally at this time.