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Cancers of the pancreas are of two main types, those arising from the part which produces enzymes to aid digestion (exocrine) and those arising from the groups of cells that produce hormones such as insulin (endocrine). Both groups of tumors may be benign (pancreatic adenomas) or malignant (pancreatic carcinomas).

A "tumor" is a lump. Most, but not all, are cancerous. A large number of different types of tumor, with a bewildering array of names, but often of confusingly similar appearance, can occur in association with the tissues around the eye.

What is a tumor of the lymphatics?
This is a tumor of the lymphatic vessels of the skin or subcutaneous tissue.

Tumors of the spleen are common in older dogs. Most enlargement of the spleen is not cancerous and due to blood accumulating as a result of poor circulation, often with bleeding within the spleen (hematomas). Sometimes excessive work in making blood components (hemopoiesis) or excessive breakdown of blood cells cause enlargement. Tissue overgrowths (hyperplasias), either of lymphoid cells or macrophages with fibrous tissue (fibrohistiocytic nodules) are also common. Less commonly, enlargement is due to infection or inflammation of the spleen (splenitis).

The testicle (testis) contains several different cell types. These include the germ cells, which make sperm, the supporting and nourishing Sertoli cells, and the hormone-producing interstitial (or Leydig) cells.

Any one or more than one of these cell types may become cancerous. The germ cells that make sperm may become cancers known as seminomas, the Sertoli cells become Sertoli cell tumors and the interstitial cells become Leydig or interstitial cell tumors. Most of the tumors are benign. The tumors are usually permanently cured by castration. This needs to be total (i.e. both testicles) as many tumors occur simultaneously in both testicles. Spread to other parts of the body (metastasis) is unusual if the cancer is surgically removed at an early stage.

The thyroid gland is a two-lobed organ wrapped partially around the front of the trachea (windpipe) just below the throat. Its function is the production and release of the thyroid hormones. Hormones are specialized chemicals that regulate and integrate many activities to maintain internal stability of the body. The hormones, as released, from the various hormone-producing sites (endocrine glands) pass directly into the blood to affect target cells elsewhere. The distinct endocrine glands besides the thyroid are the adrenals, parathyroids, pituitary and islets in the pancreas, although hormones are also produced by many cells in other tissues.

This is a common tumor, only found in dogs. It has a patchy world-wide distribution including parts of the Caribbean, USA, Southern Europe, Asia and Africa. It is transmitted by physical transplantation. It occurs in both sexes and may appear as multiple subcutaneous nodules on the genitalia, lips and other parts of the body.

These are tumors arising from structures within the eye. They tend to result in an increase in the internal pressure (glaucoma), which then leads to blindness. There is sometimes bleeding within the eye, swelling and pain.

Most swellings and tumors of the uterus are not cancerous. The most common in the bitch is cystic endometrial hyperplasia (overgrowth of the inner lining of the uterus) due to hormone stimulation. Sometimes, this reaction is deeper in the muscle layers and is called ’adenomyosis’. Secondary infection and inflammation then convert the endometrial hyperplasia into pyometra (literally pus in the womb). Cysts and polyps of the endometrium can also be part of the pyometra syndrome or be due to congenital abnormalities. They may persist when the cause is removed and may be multiple.