|Types of Cancer in Dogs
Unlike many other animals, dogs are susceptible to the same types of cancers for which humans are at risk. Dogs, for example, are the only non-human
species in which spontaneous prostate cancer occurs. Listed below are the most common types of cancer in dogs. Click on any disease type below for
more information about the definition, risk factors, causes, symptoms, diagnosis, treatment, and prognosis of that particular form of cancer.
|Bladder Cancer - Bladder cancer occurs in dogs with some breeds at higher risk than others (West highland Terriers for
example). This is a slow developing cancer and pets may not show symptoms for 3 to 6 months. Once symptoms occur,
urinary obstruction and bleeding is common.
Brain Tumors - Tumors in the brain may occur in dogs as primary or as metastatic tumors. Epileptic-like seizures or other
extreme behavioral changes may be the only clinical signs. CAT scanning will allow precise localization of these lesions.
Surgical excision followed by radiation therapy is the indicated treatment if the tumor is in an accessible portion of the skull.
Radiation therapy alone can control some inoperable tumors.
Mammary Carcinoma - Female dogs are at high risk for developing malignant mammary tumors. Mammary tumors are the
most common types of tumors in non-spayed female dogs. While 50 percent of these tumors are malignant, complete
surgical removal is sometimes curative if the cancer has not metastasized.
Mast Cell Tumors - A common malignant tumor in dogs is the mast cell tumor. Mast cells are immune cells that are
responsible for allergies. Mast cells can be found in all tissues of the body but typically form tumors on the skin in close to
20 percent in the canine population. MCTs range from relatively benign to extremely aggressive, leading to tumor spread
and eventual death. Particular breeds of dog are at risk for the development of this tumor, indicating a role for genetic
Malignant Histiocytosis - Malignant histiocytosis (MH), while rare in people, occurs frequently in certain breeds of dogs
including Rottweilers, Golden Retrievers, Flat-Coated Retrievers and Bernese Mountain Dogs. There is no reported
effective therapy for this disease. Recent work suggests Lomustine (CCNU) is helpful in extending dog survival. It occurs
with high incidence in Bernese Mountain Dogs, Rottweilers, Flat Coated Retrievers, Golden Retrievers and sporadically in
many other breeds. Histiocytic sarcomas occur as localized lesions in spleen, lymph nodes, lung, bone marrow, skin and
subcutis, brain, and periarticular tissue of large appendicular(limb) joints. Histiocytic sarcomas can also occur as multiple
lesions in single organs (especially spleen), and rapidly disseminate to involve multiple organs. Hence, disseminated
histiocytic sarcoma is difficult to distinguish from MH, which is a multi-system, rapidly progressive disease in which there is
simultaneous involvement of multiple organs such as spleen, lymph nodes, lung, bone marrow, skin and subcutis.
Response of histiocytic sarcomas and MH to chemotherapy is at best brief.
Squamous Cell Carcinomas - Squamous cell carcinoma is one of the most common cancers found in dogs. Common
sites are the mouth and the toes (nailbeds). Early detection and complete surgical removal is the treatment of choice and
fewer than 20% develop metastatic disease. SCC of the tonsil and tongue are quite aggressive and fewer than 10% survive
1 year or longer despite treatment measures.
Head & Neck - Cancer of the mouth is common in dogs. Signs to watch for are a mass on the gums, bleeding, odor, or
difficulty eating. Since many swellings are malignant, early, aggressive treatment is essential. Cancer may also develop
inside the nose of dogs. Bleeding from the nose, breathing difficulty, or facial swelling are symptoms that may indicate
cancer and should be checked by your veterinarian.
Hemangiosarcoma is an incurable tumor of cells that line blood vessels (endothelial cells). Although dogs of any age and
breed are susceptible to hemangiosarcoma, it occurs more commonly in dogs beyond middle age, and in breeds such as
Golden Retrievers, German Shepherd Dogs, Portuguese Water Dogs, and Skye Terriers, among others.
Hemangiosarcoma develops slowly and is essentially painless so clinical signs are usually not evident until the advanced
stages when the tumors are resistant to most treatments. Less than 50% of dogs treated with standard-of-care of care for
this tumor (surgery and intensive chemotherapy) survive more than six months. Many dogs die from severe internal
bleeding before there is an opportunity to institute treatment.
Lymphoma is one of the most common cancers seen in dogs and probably occurring 2 to 5 times as frequently in dogs
than in people. Although there are breeds that appear to be at increased risk for this disease, lymphoma can affect any
dog of any breed at any age. Most of the time, lymphoma appears as swollen glands (lymph nodes) that can be seen or felt
under the neck, in front of the shoulders, or behind the knee. Occasionally, lymphoma can affect lymph nodes that are not
visible or palpable from outside the body, such as those inside the chest or in the abdomen. In these cases, dogs may
accumulate fluid in the chest that makes breathing difficult, or they may have digestive problems (diarrhea, vomiting, or
painful abdomen). Lymphoma is generally considered treatable. Multi-agent chemotherapy consisting of L-asparaginase,
vincristine, cyclophosphamide, doxorubicin, and prednisone, is the standard-of-care for this disease. However, there are
various subtypes of lymphoma that exhibit different behaviors, and some of the more aggressive types are unresponsive to
any available treatment.
Melanoma occurs commonly in dogs with pigmented (dark) skin. Melanomas arise from pigment producing cells called
melanocytes, which are responsible for coloring the skin. Any dog can be affected, but Gordon Setters, Standard and
Miniature Schnauzers, Doberman Pinschers, and Scottish terriers, among others, are at increased risk to develop
melanoma, suggesting that this disease may have a hereditary component. Melanomas can occur in areas of haired skin,
where they usually form small, dark (brown to black) lumps, but can also appear as large, flat, wrinkled masses. Melanoma
of the haired skin in dogs is usually a benign tumor, although it can cause severe discomfort. In contrast, malignant
melanoma, which develops in the mouth or in the distal limbs (usually the toenail beds), is an incurable disease. These
tumors have very often spread to distant parts of the body (metastasized) by the time they are first noticed, making
complete surgical removal impossible. Radiation therapy can help extend the lives of affected dogs, but also is ineffective
against tumor cells that have metastasized. Chemotherapy is also not considered capable of adequately controlling canine
malignant melanoma. Melanoma seems to be uniquely responsive to immune-based therapies, and various novel
approaches are under development to treat this disease.
Osteosarcoma is the most common type of primary bone cancer in dogs, accounting for up to 85% of tumors that
originate in the skeletal system. Although it is mostly a disease of older large or giant breed dogs, it can affect dogs of any
size or age. Osteosarcoma may be found in many areas, but it most commonly affects the bones bordering the shoulder,
wrist and knee. The first sign an owner usually sees with this disease is lameness in the affected leg. They may also notice
a swelling over the area or their dog may seem painful at the site. The tumors are very aggressive and metastatic, so it is a
fair assumption that at the time of diagnosis the disease will have already spread beyond the primary site. For this reason,
the standard-of-care for bone cancer includes surgery to remove the primary tumor, followed by chemotherapy to attack
the cells that have left the site. In dogs, approximately 50% survive one year with standard-of-care, less than 30% survive 2
years, and less than 10% reach 3 years.
Testicular - Testicular tumors are common in dogs, especially those with retained testes. Most of these cancers are
preventable with castration (neutering) and curable with surgery if done early in the disease process.
|Click on the type of cancer for more information
Mast Cell Tumors
Osteosarcoma (Bone Cancer)
Dogs have 35 times as much skin cancer as do
humans, 4 times as many breast tumors, 8
times as much bone cancer, and twice as high
an incidence of leukemia. The only types of
cancer that are more frequently seen in humans
than in small animals are not surprising: lung
cancer is 7 times higher in humans, and
stomach/intestinal malignancies are 13 times
more frequent in man than in dogs and cats. It is
clear that the higher incidence of lung cancer in
man is due to the human habit of smoking---but
the cause of the higher incidence of
gastrointestinal malignancies in man is not so
(Texas A&M Veterinary School)
Dog Cancer Facts
80 million - the number of dogs in the U.S.
20 million - the number of dogs that will die of
cancer in the U.S.
1 million - the number of people diagnosed with
cancer in the U.S.
60% -percentage of Golden Retrievers that die
Canine cancer affects some breeds more
Dog breeds most likely to get cancer and the
type of cancer they are most susceptible to:
Bernese Mountain Dog - histiocytic sarcoma
Boxer - lymphoma and brain cancer
Cocker Spaniel - lymphoma
Golden Retriever - lymphoma and
Labrador Retriever - lymphoma nd
English Springer Spaniel - Mammary gland
Pug - mast cell
Shar-pei - mast cell
Greyhound - osteosarcoma
Rottweiler - osteosarcoma
Collie - nasal cancer
Scottish Terrier - transitional cell carcinoma
(bladder) and melanoma
Chow chow - stomach cancer
Flat Coated Retriever - transitional cell
carcinoma (bladder) and melanoma
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