> Types of Cancer in Dogs
Types of Dog Cancer
This page looks at different types of dog cancer, causes of cancer in dogs, the most common types of cancer in dogs,
some less common types of cancer in dogs, as well as some dog breeds that are predisposed to various types of cancer.
Cancer, to put it very simply, starts when there is DNA mutation causing some genes in a cell to be damaged, changed, or defective. If these cells with damaged genes cannot
be destroyed by the body's immune system, they will grow uncontrollably and cancer will then be established in the body.
Most healthy normal cells are genetically programmed to live only for a limited period of time, after which they die (a process called apoptosis). However, in cancer
cells, the gene that causes cell death is inactivated, enabling cancer cells to live and reproduce out of control.
Unlike most other diseases which tend to stay localized in one site of the body where they started, cancer can spread and take over control of other body sites. They do so
in two ways. The first way is by sending cancerous cells into healthy neighboring areas. This is called "local invasion". The second way is by cancerous cells getting
into the bloodstream or the lymphatic system and flowing around the body. Some such cells will attach to new areas in the body and start forming another tumor.
When this happens, it is said that "metastasis" has occurred, or that the cancer has "metastasized".
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It is extremely difficult, if not impossible, for veterinarians to pinpoint the exact cause for any types of dog cancer. However, many veterinarians believe that many
types of cancer in dogs are brought on by chronic inflammation and free radicals. When an area in the dog's body is inflamed, lots of free
radicals are produced which can damage the DNA of the cells in the inflamed area. Prolonged or chronic inflammation can therefore set the stage for DNA mutation which,
as mentioned above, is the beginning of cancer.
Other possible causes or factors that may trigger cancer in dogs include:
Causes of Different Types of Dog Cancer
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- Carcinogens (cancer-causing agents such as certain chemicals in pesticides, food preservatives, car exhaust, cigarette smoke, paint, etc.)
- Certain viruses
- Frequent exposure to radiation (e.g. X-rays, TV)
- Not spaying the dog (e.g. can increase the risk of some cancers such as breast cancer)
- Spaying the dog (e.g. can increase the risk of some other cancers such as osteosarcoma and bladder cancer in males)
There are quite a few types of dog cancer that can occur in dogs, some more common than others. The most common canine cancers include:
Types of Dog Cancer - Most Common Canine Cancers
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- Mast cell tumors: Mast cell tumors arise from tissue mast
cells. Although mast cell tumors can occur in different areas in the body, they most commonly occur on the skin and is the most common form of
canine skin cancer, accounting for 16 to 21% of all skin tumors in dogs.
- Lymphosarcoma: Lymphosarcoma is cancer arising from the lymphocytes
in the lymphatic system. Lymphosarcoma in dogs is a common cancer, making up approximately 7 to 25% of all canine cancers. The lymph nodes are most commonly affected
although other organs can also be affected (e.g. the liver and
- Malignant Melanoma: Melanoma is a form of malignant
skin tumor that arises from melanocytes, the cells in the skin that produce dark pigment.
Most cases of oral cancer in dogs are in the form of melanoma.
- Hemangiosarcoma: Canine hemangiosarcoma is a soft tissue tumor
that arises out of blood vessels. It commonly occurs in the spleen, the liver, and the
- Brain Tumors: Canine brain tumors can be primary or metastatic.
Brain tumors occur very commonly in older dogs, regardless of gender or breed. In fact, it has been found that 95% of older dogs over the age of 7 suffer from some form of
- Osteosarcoma: Osteosarcoma is the most common form of bone cancer
in dogs. It is very aggressive, grows fast causing pain and lameness in dogs, and can metastasize to other sites. Osteosarcoma occurs more frequently in middle-aged to
- Mammary Tumors: Tumors of mammary glands are the most common
tumors in dogs, especially among unspayed females. Malignant mammary tumors are mostly carcinomas (e.g. tubular adenocarcinomas) but they can sometimes be osteosarcomas or
fibrosarcomas. Spaying a dog before her first heat cycle (around 6 months of age) can significantly reduce her chance of getting breast cancer.
Besides the above more common types of cancer in dogs, there are some relatively rare types of dog cancer. However, these types of cancer are nonetheless life-threatening.
Types of Dog Cancer - Less Common but Fatal Dog Cancers
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- Bladder Cancer: The most common form of dog bladder cancer
is a malignant cancer tumor called transitional cell carcinoma (TCC). TCC is fairly aggressive and can spread to other sites of the body, such as the lungs, the bones,
or the lymph nodes near the bladder. Bladder cancer in dogs is not very common (about 2% of all dog cancers).
- Primary Liver Cancer: The most common primary malignant liver tumor
is hepatocellular carcinoma which is locally invasive but rarely metastasize. Primary liver cancer is not common (less than 1.5% of all dog cancers), and tends to occur in
- Primary Lung Cancer: The most common primary lung tumors are
malignant carcinomas (often adenocarnimas), although they can be hemangiosarcomas. Primary lung cancer is rare but deadly. The tumors are very aggressive and usually
will have already spread to other parts of the body by the time they are diagnosed. Primary lung cancer tends to occur in older dogs.
- Pancreatic Cancer: The most common form of pancreatic
tumors is adenocarcinoma which is malignant and aggressive. These tumors are locally invasive and can metastasize to other sites in the body. Pancreatic cancer in dogs
is uncommon (less than 0.5% of all canine cancers) and occurs more frequently in older dogs.
- Stomach Cancer: Dog stomach cancer is most frequently caused by
adenocarcinoma which is aggressive and can frequently spread to lymph nodes, the liver and the lungs. Canine stomach cancer is rather rare (about 0.1% of all
cancers in dogs).
- Prostate Cancer: The most common type of dog prostate cancer
is carcinoma (such as prostatic adenocarcinoma) which is a highly aggressive and invasive form of cancer and can metastasize rapidly to other sites in the body, such as the
lymph nodes, bones and lungs. Prostate cancer is not common in dogs (about 0.2 to 0.6% of all canine cancers); however, it is an aggressive form of cancer and is
often fatal. Canine prostate cancer is not influenced by testosterone and as such it can affect both neutered and intact male dogs.
- Nasal Cancer: The most frequently occurring nasal tumor in dogs is
squamous cell carcinoma (SCC), although fibrosarcoma and many others can also occur. Both carcinomas and sarcomas are locally invasive and can invade vital surrounding
structures such as the throat. Some tumors also metastasize to more distant areas of the body. Canine nasal tumors are not very common (about 1% of all tumors in dogs).
Older dogs are more prone to nasal cancer.
- Leukemia: The most common form of canine leukemia is lymphocytic
leukemia which can be acute or chronic. Both the acute and chronic stages of lymphocytic leukemia are rare in dogs. Acute leukemia usually affects middle-aged dogs or
older (6 years or older), while chronic leukemia occurs more frequently in older dogs (10-12 years of age).
Generally speaking, mixed breed dogs are less prone to cancers than purebred dogs.
Below is a list of common types of dog cancer and some dog breeds that are predisposed to those cancers. (Please remember that this is not a complete list):
Dog Breeds Predisposed to Different Types of Dog Cancer
|Type of Cancer
||Labrador Retriever, German Shepherd, Golden Retriever
||Bernese Mountain Dog
||Airedale Terrier, Bassett Hound, Boxer, Bulldog, Cocker Spaniel, Golden Retriever, Labrador Retriever, Rottweiler, St. Bernard,
||Boston Terrier, Dachshund, English Spring Spaniel, Poodle
|Mast Cell Tumors
||Beagle, Boston Terrier, Boxer, Labrador Retriever, Pug, Rhodesian Ridgeback,
||Airedale Terrier, Boston Terrier, Boxer, Chihuahua, Chow Chow, Cocker Spaniel, Doberman,
Golden Retriever, Irish Setter, Scottish Terrier, Springer Spaniel
||Boxer, Doberman Pinscher, the Great Dane, German Shepherd, Golden Retriever,
Irish Setter, Rottweiler, Saint Bernard
|Subungal Squamous Cell Carcinoma
|Transitional Cell Carcinoma
||Beagle, Shetland Sheepdog, West Highland White Terriers, Wire Hair Fox Terriers