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Cancer in Canines

Information on the following types of cancer are provided on this page:
  • Hemangiosarcoma
  • Osteosarcoma
  • Lymphoma
  • Malignant histiocytosis
  • Melanoma (oral and digital)

Hemangiosarcomas are a form of cancer which originates in the endothelium, which is the lining of blood vessels and spleen. As might be expected of a tumor arising in the blood system they are highly malignant and can be found almost anywhere in the body since blood vessels are necessary in almost all body tissues. There is a strong predilection for the spleen, pericardium and heart. These tumors are most common in middle aged or older dogs which are medium sized or larger but can occur in any breed. German shepherds are reported to be more susceptible to this tumor than most dog breeds. In our practice golden retrievers also seem to have a higher than normal incidence.

Because these tumors arise in internal organs there is often little warning that they are present prior to time they cause severe clinical signs of disease. A common estimate of the average time from discovery of the tumor until death occurs in affected dogs is six to eight weeks but death occurs more rapidly than this in a number of cases.

Symptoms of Hemangiosarcomas in Dogs
Visible bleeding, usually in the form of nosebleeds, and signs associated with blood loss, such as tiring easily, episodes of unexplained weakness, pale color to the mucous membranes of the mouth and eyes, increased respiratory rates, abdominal swelling and depression are the most common presenting signs for patients with hemangiosarcoma. A few dogs just suddenly die with no clinical signs having been noted by their families prior to death. Bleeding disorders associated with hemangiosarcoma are sometimes confused with immune mediated hemolytic anemia (IMHA) because the type of anemia caused by the two conditions is very similar and early clinical signs are often very similar, as well. Hemangiosarcomas can cause very large tumors, sometimes as large as ten or more pounds, when they affect the spleen.

In most instances tumors of this size in this location are found on physical exam. In other cases the tumor affects the heart and is hard to find on a physical exam and even easy to miss or X-rays. Sometimes there are hundreds of small tumors spread throughout the body and surgical exploration or an autopsy are the only ways to identify the problem.

Disseminated Intravascular Coagulation (DIC) Usually Accompanies Hemangiosarcoma

The blood disorder that most commonly accompanies the presence of hemangiosarcoma tumors is disseminated intravascular coagulation (DIC). This is blood clotting that is occurring inappropriately inside the blood vessels. It uses up all of the blood clotting elements rapidly and dogs with this condition usually have platelet deficiencies, increased blood clotting times, decrease in fibrin content in the blood and an increase in fibrin degradation products (FDPs). This is probably the cause of death in most dogs affected with hemangiosarcoma.

Diagnosis of hemangiosarcoma can be accomplished in a number of ways. Identification of a tumor in the spleen or heart raises a high degree of suspicion for this tumor. Abdominal swelling is also highly suggestive in an older large breed dog. If fluid is aspirated from the abdomen and it looks like blood it is even more suggestive of hemangiosarcoma. If blood is drawn and will not clot when left in the syringe it is another sign that a dog may have this tumor. In some cases careful evaluation of the type of bleeding disorder present is necessary to raise the suspicion of hemangiosarcoma.

Hemangiosarcoma Treatment in Dogs
If a tumor is identified when it is small it may be possible to remove the spleen if the tumor is there or even to remove tumors found near the heart and prolong the pet's life. Most of the time this will not make much difference, though. These are highly malignant tumors and most have spread by the time they can be identified. To the best of my knowledge there is not a very successful hemotherapeutic or radiation protocol for this cancer at this time but dogs treated with chemotherapeutic agents do live a little longer than dogs that do not receive this treatment.

Treatment for the bleeding disorders and aggressive supportive care also prolong the life of patients with hemangiosarcoma. If treatment for IMHA or immune mediated thrombocytopenia (ITP) are instituted due to confusion over the underlying cause of clinical signs early in the diagnostic process there is not likely to be any harm to the dog.

Due to the tendency to look for an inciting agent in IMHA and ITP it is a good idea to consider an autopsy exam if a dog dies before a definite diagnosis of any of these conditions can be made. Finding hemangiosarcoma saves a lot of agonizing over possible causes of the death of a friend. There are no known predisposing factors other than size and breed that I am aware of for hemangiosarcoma.


Osteosarcoma (and other types of bone cancer in Canines)
 There are many different types of cancerous tumors that dogs can get; however, bone cancer can be one of the more difficult to diagnose because the tumors don't show up as readily. There are many different types of bone cancer that can develop in dogs. Some are more common than other, but here are the 6 most common forms of dog bone cancer.

1.  Osteosarcoma Is the Most Common Bone Cancer.

Osteosarcoma, often referred to as OSA, is the most common type of bone cancer that develops in dogs. OSA destroys a dog's bones from the inside out. It can be very painful for you dog has the tumor continues to grow. OSA is most common in older, large breed dogs.

2.  Chondrosarcoma, which is referred to as CSA, is the second most common type of bone cancer that is found in dogs. CSA is a cancer of the cartilage and usually found in bones that are flat like the skull or the ribs. This, on average, is not as malignant as OSA and can usually be treated by removing the tumor.  Many dogs get Chondrosarcoma Bone Cancer.

3.  Fibrosarcoma is a fairly rare form of bone cancer and is often called FSA. This cancer is typically treated through surgery on the infected area. The surgery can involve amputation of the effected area. This bone cancer is usually found in the jaw, ribs and vertebrae.

4.  Hemangiosarcoma Usually Affects Younger Dogs.

This is also a rare form of bone cancer that only impacts about 5% of dogs that have bone cancer. This form of cancer usually effects younger dogs and is often treated with medication and amputation.

5.  Multilobular Osteochondrosarcoma is Very Rare.

This kind of tumor is very rare and occurs in the lining of the bone, most often in the skull. Treatment options include surgery, but because of where the tumors are often located, surgery can be difficult.

6.  Primary Joint Tumors

This cancer is a little more common in dogs. A dog with this cancer will start to show symptoms that aren't all that uncharacteristic of osteoporosis dogs get. The recommended treatment is amputation, but chemotherapy is an option you could also discuss with your veterinarian.

While the bone tumor dogs get may vary in type, the most common treatment is amputation. This may seem extreme, but if it can limit the effect of the tumor on your dog it may be worth it. The treatment decision will be a discussion that you and your veterinarian will need to have.


Canine Lymphoma

Canine Lymphoma (Lymphosarcoma) is an immune dysfunction disease. It is a progressive fatal disease of dogs characterized by neoplastic transformation and proliferation of lymphoid cells, usually originating in solid lymphoid organs (lymphosarcoma) or bone marrow (lymphocytic leukemia).

There are several forms of canine lymphoma including multicentric lymphoma, alimentary lymphoma, mediastinal lymphoma, and cutaneous lymphoma:


  • Multicentric canine lymphoma involves the lymph nodes and the lymphatic organs. This diffuse form of lymphoma can cause enlarged, but painless lymph nodes on the neck, under the front legs, and in the groin area. In some cases these nodes can grow to the size of golf balls or baseballs overnight.
  • Alimentary lymphoma occurs in the digestive tract. Symptoms may not be present until the late stages of the disease. Dogs that have alimentary canine lymphoma will become emaciated and they will also have diarrhea. Vomiting will be present. The vomiting and diarrhea is the result of growing tumors that cause obstruction of the processing and passage and present symptoms of vomiting and diarrhea. 
  • Mediastinal lymphoma is a rare form of canine lymphoma. It develops in the center of the chest and it is usually associated with the thymus glands. Symptoms of this form of lymphoma include fatigue and difficulty breathing. 
  • Cutaneous lymphoma affects the skin but may also involve superficial lymph nodes. With this form of the disease, a number of raised lesions or pale plaques will be visible on the skin. 
 Although specific symptoms depend on the form of canine lymphoma, general symptoms for all forms of the disease include fever, weight loss, and anorexia (loss of appetite).
Treatment options for canine lymphoma include chemotherapy, surgery, and specialized compounds called "immune modulators." Nutritional therapy includes adopting a low carb diet and a diet rich with Omega 3 fatty acids. While the typical canine lymphoma patient is a middle-aged dog, canine lymphoma can strike at any age. You should have your pet examined regularly in order to increase your chances of catching the disease in the early stages. It is important to keep in mind that if left untreated, canine lymphoma will lead to death.  Most importantly:  Please see your veterinarian for a full discourse on treatment options.


Malignant Histiocytosis (a category of Dog Cancer Lumps)
 Dogs develop many types of skin lumps, most of which aren't cause for concern, but a few are cancer lumps and should be immediately evaluated by a veterinarian.  Here are the following types, among which is malignant histiocytosis.Histiocytosis

Malignant Histiocytosis

There are three forms of histiocytosis, and only one of them is malignant. However, all three look similar, forming large, hairless nodules, which usually have ulcers. The malignant form affects both the skin and internal organs and has no known effective treatment.


Lymphoma is a common dog cancer that can occur in the liver, spleen, lymph nodes and other organs. Those that occur in the lymph nodes are often seen on the skin. However, you may be able to feel other internal lumps with regular inspections. Tumors may develop in the lymph nodes and swell, but cause no other symptoms. Additional symptoms include itching, redness and ulcers around the tumor. Treatment usually involves removal of the tumor, radiation treatment and/or chemotherapy, which can have varying degrees of success. Treatment is usually less effective on lymphoma of the skin.

Sarcoma Tumors

Two common types are fibrosarcoma and hemangiosarcoma. Both are associated with the skin and are very aggressive. Since they may spread quickly, immediate action is required. Most veterinarians recommend removal, even if that means large chunks of muscle and bone. Amputations may also be required.

Fibrosarcoma is usually associated with vaccinations or injections and forms at that site, most commonly in between the dog's shoulder bones, where they receive most injections. These tumors form strange shapes and are very firm.

Hemangiosarcoma are usually caused by sun damage and may appear on the chest or abdomen. They often ulcerate and are usually dark in color.

Mast Cell Tumors

This is another common cancer that exhibits itself in the form of tumors. In this case, one or more tumors may be present, varying in size and location. Some mast cell tumors are very small and easily overlooked. They may appear smooth, bumpy or ulcerated and may be dark or discolored.

Mast cell tumors are usually grouped into grades, which vary from level 1 to 4. Level 1 are the most slow-growing while level 4 are fast-growing and likely to metastasize. Treatment and prognosis vary largely on the grade of cancer and the advancement of the tumor.

Cell Carcinoma

Another common type of tumor is squamous cell carcinoma, which is commonly associated with sun damage or chronic skin problems. These tumors may appear one of two ways: cauliflower-shaped lesions that are commonly ulcerated and appear most commonly on the lips and nose or larger, crusty ulcers that appear on the legs or other parts of the body where skin irritation may occur. Treatment of these tumors may involve surgical removal or radiation, depending on the location.

Basal Cell Tumors

Many types of tumors that appear on your dog's body can be cancerous or benign. Basal cell tumors are an example of this. Though this type of tumors is a cause for concern, it may also be benign. Basal cell tumors form into lumps, often around your dog's head, neck or chest. They may be fluid-filled, causing them to feel squishy, or dark in color, but this is not always the case. Because these tumors don't often metastasize, they can usually be removed, if cancerous, without requiring chemotherapy




 Canine melanoma is a malignant tumor. A melanoma is manifested through skin lesions that have unusual shapes or colors. Moles can turn into melanomas when they suddenly change shape and color. A melanoma is made up of melanocytes, which are the cells that also determine the dark pigmentation of the skin. Canine melanomas are typically located on the skin, toes, mouth or behind the eyes. Melanomas are more frequent in white coated dogs and certain dog breeds. Cancer is a serious disease and should be detected as early as possible, so as to be able to stop it from spreading and improve the life quality of the pet.

Symptoms of Canine Melanoma

Melanoma in dogs may pass unnoticed due to the coat, which covers the skin and the location of the lesions.

The most visible signs of melanoma are on the skin in the form of lesions that are dark in color and have irregular shapes. Watch out for moles that change their size, color and shape and can turn into melanomas. These moles may be itchy and can frequently bleed. Melanomas may also occur in the dog's mouth or on the toes. When the mouth is affected, there will be other symptoms such as bad breath, excessive drooling, sneezing, coughing or trouble swallowing. This may also cause refusal to eat and weight loss.

When the cancer is in metastasis, the dog will experience fatigue, nausea, depression and behavioral changes.

Causes of Canine Melanoma

Melanomas in dogs don't have a clearly established cause, but may be linked to genetics and extended sun exposure, especially in white coated dogs. Certain breeds are more susceptible to having melanomas. It is important to keep white coated dogs away from sun and use suitable sun screen, to prevent the occurrence of melanomas.

Diagnosing Canine Melanoma

Melanomas in dogs can be diagnosed through a medical examination. The vet must establish how advanced the cancer is. Blood tests may reveal a low white blood cell count. X-rays are also performed to establish if the cancer is in metastasis. The melanoma may also be checked, and in some cases a biopsy will be performed.

Treatment Options

The treatment of canine melanoma should focus on removing the melanoma or preventing the cancer from spreading. The vet will establish if surgery is possible or recommended. If surgery is not possible, the vet will prescribe chemotherapy and radiation therapy.

However, even with surgery or treatment, the cancer can still reoccur or spread further. The dog should be carefully monitored and any alarming signs should be reported to the vet. A dog with melanoma can live a quality life, provided he gets the necessary care and treatment.

It is highly important that the dog is groomed on a regular basis, so that you detect possible melanomas as early as possible. Check inside the mouth for dark spots or lesions and look at the toes as well. The early detection of a melanoma can help the vet administer therapy and possibly prevent the cancer from spreading through the rest of the body.

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