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Cancer and Tumors
What is Cancer?
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    What is Cancer?

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    Cancer is a group of abnormal cells often—though not always—consolidated into a mass called a tumor. The common characteristic of all cancer cells is the absence of normal growth control mechanisms. Normal, healthy cells grow and reproduce only to replace cells that have died or, in young animals, to support ordinary growth and development. Cancer cells have no such restraints; they keep growing and reproducing even when there is no need for new cells. They often invade and damage or destroy nearby healthy cells.

    Any tissue in a body can develop cancer cells; no area of a body is immune to cancer. More than 100 types of cancer are known. Cancers are named based on the type of cell or organ in which the cancer develops. Thus, as an example, hepatocellular carcinoma is a specific type of cancer involving the liver.

    PrintOpen table in new window Open table in new window
    Common Cancers in Domestic Animals

    Type of Cancer

    Tissue Usually Affected

    Reference

    Dogs

    Bladder cancer

    Urinary bladder

    see Kidney and Urinary Tract Disorders of Dogs: Lower Urinary Tract Tumors

    Brain tumor

    Brain

    see Brain, Spinal Cord, and Nerve Disorders of Dogs: Tumors of the Nervous System

    Lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Dogs: Lipomas and Liposarcomas

    Lymphoma

    Lymph nodes, spleen, bone marrow

    see Blood Disorders of Dogs: Canine Malignant Lymphoma

    Malignant histiocytosis

    Skin

    see Skin Disorders of Dogs: Histiocytic Cell Tumors

    Mammary carcinoma

    Breast (mammary gland)

    see Reproductive Disorders of Dogs: Mammary (Breast) Tumors in Dogs

    Mast cell tumor

    Skin

    see Skin Disorders of Dogs: Mast Cell Tumors

    Melanoma

    Skin

    see Skin Disorders of Dogs: Melanomas

    Osteosarcoma

    Bone

    see Bone, Joint, and Muscle Disorders of Dogs: Bone Tumors

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Dogs: Squamous Cell Carcinomas

    Cats

    Ceruminous gland adenocarcinoma

    Ear canal

    see Ear Disorders of Cats: Tumors of the Ear Canal in Cats

    Fibrosarcoma

    Skin, subcutaneous tissue

    see Skin Disorders of Cats: Soft Tissue Sarcomas

    Infiltrative lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Liposarcoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Mammary tumor

    Breast (mammary gland)

    see Reproductive Disorders of Cats: Mammary (Breast) Tumors in Cats

    Mast cell tumor

    Skin

    See see Skin Disorders of Cats: Mast Cell Tumors

    Osteosarcoma

    Bone

    see Bone, Joint, and Muscle Disorders of Cats: Bone Tumors

    Sebaceous hyperplasia/adenoma

    Skin

    see Skin Disorders of Cats: Sebaceous Gland Tumors

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Cats: Squamous Cell Carcinomas

    Synovial cell sarcoma

    Joint

    see Bone, Joint, and Muscle Disorders of Cats: Cancerous Arthritis

    Vaccine-associated sarcoma

    Skin, subcutaneous tissue

    see Skin Disorders of Cats: Vaccine-associated Tumors

    Horses

    Lymphoma

    Lymph nodes, spleen

    see Blood Disorders of Horses: Leukemia and Lymphoma

    Melanoma

    Skin

    see Skin Disorders of Horses: Melanomas

    Sarcoid/fibrosarcoma of the skin, mouth, and salivary glands

    Skin, mouth, salivary gland

    see Skin Disorders of Horses: Equine Sarcoids

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Horses: Squamous Cell Carcinomas

    Common Cancers in Domestic Animals

    Type of Cancer

    Tissue Usually Affected

    Reference

    Dogs

    Bladder cancer

    Urinary bladder

    see Kidney and Urinary Tract Disorders of Dogs: Lower Urinary Tract Tumors

    Brain tumor

    Brain

    see Brain, Spinal Cord, and Nerve Disorders of Dogs: Tumors of the Nervous System

    Lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Dogs: Lipomas and Liposarcomas

    Lymphoma

    Lymph nodes, spleen, bone marrow

    see Blood Disorders of Dogs: Canine Malignant Lymphoma

    Malignant histiocytosis

    Skin

    see Skin Disorders of Dogs: Histiocytic Cell Tumors

    Mammary carcinoma

    Breast (mammary gland)

    see Reproductive Disorders of Dogs: Mammary (Breast) Tumors in Dogs

    Mast cell tumor

    Skin

    see Skin Disorders of Dogs: Mast Cell Tumors

    Melanoma

    Skin

    see Skin Disorders of Dogs: Melanomas

    Osteosarcoma

    Bone

    see Bone, Joint, and Muscle Disorders of Dogs: Bone Tumors

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Dogs: Squamous Cell Carcinomas

    Cats

    Ceruminous gland adenocarcinoma

    Ear canal

    see Ear Disorders of Cats: Tumors of the Ear Canal in Cats

    Fibrosarcoma

    Skin, subcutaneous tissue

    see Skin Disorders of Cats: Soft Tissue Sarcomas

    Infiltrative lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Lipoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Liposarcoma

    Fat, subcutaneous tissue

    see Skin Disorders of Cats: Lipomas and Liposarcomas

    Mammary tumor

    Breast (mammary gland)

    see Reproductive Disorders of Cats: Mammary (Breast) Tumors in Cats

    Mast cell tumor

    Skin

    See see Skin Disorders of Cats: Mast Cell Tumors

    Osteosarcoma

    Bone

    see Bone, Joint, and Muscle Disorders of Cats: Bone Tumors

    Sebaceous hyperplasia/adenoma

    Skin

    see Skin Disorders of Cats: Sebaceous Gland Tumors

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Cats: Squamous Cell Carcinomas

    Synovial cell sarcoma

    Joint

    see Bone, Joint, and Muscle Disorders of Cats: Cancerous Arthritis

    Vaccine-associated sarcoma

    Skin, subcutaneous tissue

    see Skin Disorders of Cats: Vaccine-associated Tumors

    Horses

    Lymphoma

    Lymph nodes, spleen

    see Blood Disorders of Horses: Leukemia and Lymphoma

    Melanoma

    Skin

    see Skin Disorders of Horses: Melanomas

    Sarcoid/fibrosarcoma of the skin, mouth, and salivary glands

    Skin, mouth, salivary gland

    see Skin Disorders of Horses: Equine Sarcoids

    Squamous cell carcinoma

    Skin

    see Skin Disorders of Horses: Squamous Cell Carcinomas

    While many types of cancer cause the development of tumors, not all tumors are malignant (cancerous). Tumors can be benign (noncancerous). Benign tumors, while they may need to be treated or removed, are not usually as dangerous as malignant tumors. Malignant tumors invade and destroy nearby cells and organs. They can be difficult to remove because of the involvement of nearby organs. Further, malignant tumors often spread (metastasize) to other parts of the body through the lymphatic system or the bloodstream.

    Last full review/revision July 2011

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