Stages of Cancer in Dogs

A diagnosis of cancer in a beloved dog can be devastating and confusing. Deciphering the extent of the illness and the prognosis of the different stages can complicate crucial decisions. Although different cancers have slightly different stages, the National Cancer Institute grades cancers in four stages, Stage I, II, III and IV. Veterinarians apply these stages to dog cancers as well.

  1. Stage I

    • Catching cancer in dogs at Stage I is the ideal. Stage I indicates that the cancer is localized. Localized cancer has more treatment options, such as a tumor removal or chemotherapy, depending on the type of cancer. Prognosis is typically good when caught at Stage I.

    Stage II

    • Stage II cancer in dogs indicates that the cancer has spread to some of the surrounding region. Multiple tumors may be present. Veterinarians may be able to treat Stage II cancer with tumor removal and chemotherapy, though the prognosis is not as good as Stage I.

    Stage III

    • Stage III cancer has extensive regional spread. This can include spread to lymph nodes and nearby organs or tissue, depending on the type of cancer. Aggressive treatment is possible, though the likelihood of survival is limited. With Stage III cancer, life expectancy is less than 12 months, even with treatment.

    Stage IV

    • A dog with Stage IV cancer has widespread malignant cells and multiple organ involvement. The cancer has spread extensively. Prognosis with Stage IV cancer is grave, even with aggressive treatment.