Stages of Cancer in Dogs

Stages of cancer in dogs are used to determine if a particular type of cancer has spread and what the prognosis of the dog’s condition is. These stages are also one of the most helpful indicators for determining what type of treatment will be most effective against a given type of cancer. Cancer in dogs is probably more common that most dog owners suspect. In fact, cancer is responsible for nearly 50% of deaths in dogs each year. However, by understanding the stages of cancer, dog owners will be more informed about how they can make the best treatment decisions for their dog.

Dog Lymphoma in Cancer

Dog lymphoma is a type of cancer which primarily affects the lymph nodes or uses the lymph nodes a means of transportation to other areas of the dog’s body. For this particular type of cancer in dogs, there are five stages including:

  • Stage I – Enlargement of just one lymph node. In general, stage I means that the cancer has been localized to only one lymph node.
  • Stage II – Enlargement of multiple lymph nodes. However, stage II recognizes lymph nodes which primarily affect either the front half of the dog’s body or the back half of the dog’s body.
  • Stage III – Enlargement of multiple lymph nodes. The difference in staging between stage II and stage III is that stage III lymphoma cancers affect both the front and back half of the dog’s body.
  • Stage IV – This stage indicates metastases, or spreading, of the cancer to the liver, the spleen or both.
  • Stage V – This is the most invasive of lymphoma cancer stages in dogs. During stage V, the bone marrow may be affected as well as other body systems including the gastrointestinal tract or the nervous system.

Each lymphoma cancer stage in dogs is divided into substages, “a” or “b”. Dogs within a given stage with substage “a” are known to be asymptomatic, meaning that they feel well and do not appear to be affected symptomatically by the cancer. However, dogs with substage “b” are those that experience symptoms of the cancer and appear clinically ill.

Mast Cell Cancer

Mast cell cancer in dogs is a tumorous type of cancer which affects any area of the dog’s body. In most cases, this type of cancer is considered invasive and thus is difficult to surgically remove. Mast cell cancers in dogs have three levels of grading, including:

  • Grade I – This stage of cancer in dogs is considered the least aggressive in that it may only affect one area of the body, and it is not considered likely to spread throughout the body.
  • Grade II – Tumors at this level are still considered stable and are not expected to metastasize. However, grade II recognizes that tumors have a greatly likelihood of metastasis than grade I tumors.
  • Grade III – Cancers at this level are considered very aggressive and are almost guaranteed to spread to other areas of the dog’s body.