Skip to content

Educational Articles

Dogs + Tumors

  • These are tumors arising from structures within the eye. The most common intraocular tumors originate from the melanin producing cells (discussed in a separate handout).

  • Melanocytes are cells that produce a pigment called melanin. They are found in many parts of the body where there is pigment, particularly the skin, hair and eyes.

  • A 'tumor' is a lump. Some tumors are cancerous and some are benign. There are several different types of tumors that occur in the tissues around the eye. Many of these tumors have physical effects on the eye, causing soreness, redness and weeping. The most common treatment for tumors around the eye is surgical removal of the lump.

  • Fibrosarcomas and spindle cell tumors originate from the connective tissue of, or beneath, the skin. The tumor is diverse in appearance and several different cell lines produce tumors of similar appearance.

  • It is important to recognize that multiple tumors in the liver are not always cancers. The livers of older dogs may become nodular without causing any clinical effects.

  • The liver has a massive blood supply so many cancer cells from elsewhere arrive within it and start to grow. In dogs, metastatic tumors are three times as common as primary tumors and over 30% of malignant cancer may metastasize to the liver.

  • Most primary lung cancers originate from the epithelium lining the airways. In dogs, most develop in the alveoli where oxygen is taken up into the body, but in people and in cats most originate in the main airways (bronchi).

  • Lymphatic tumors are rare in pets. Lymphangiomas are benign and lymphangiosarcomas are malignant and have a moderate-to-high metastatic potential. Patients with lymphatic tumors typically have severe edema because of lymphatic obstruction. These types of tumors occur more frequently in young dogs and cats. Treatment usually involves surgical excision and chemotherapy may be used as a follow-up treatment in the case of lymphangiosarcomas.

  • Lymphocytes are specialized cells that function as part of the body's immune system, and are key cells in the body's ability to fight and prevent infection. Lymphocytes are found in the blood and tissues throughout the body, and are in particular concentration in lymph nodes and other 'lymphoid tissue'.

  • Lymphoma is a cancer of the lymph nodes and lymphatic system. This cancer may be localized to one particular region, or may spread throughout the entire body. Lymphoma is a relatively common cancer, accounting for 15-20% of new cancer diagnoses in dogs. The prognosis for lymphoma varies, depending on various characteristics that can only be determined by specialized testing.