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What is Leiomyosarcoma?

Neoplasia or abnormal tissue growths form all over the body; some are benign while others are malignant cancer tumors. Of all the malignant neoplasia found in dogs, 1 to 3% occur in the gastrointestinal tract. Leiomyosarcoma is the second most common type of GI cancer, making it still rather rare in dogs. It usually affects older dogs, with a median onset of around 10 years. It is characterized by a tumor which forms in the smooth muscle cells along the walls of the GI tract, usually in the stomach or small intestine. It commonly metastasizes at a rate of 16-30% which is not as high as some cancers, but still indicates that the tumors will spread, often to other organs like the liver or spleen. Tumors can also lead to perforation of the walls of the stomach or bowels. Even with surgery, most dogs survive only a matter of months.

There are several different types of gastrointestinal cancer in dogs. Tumors that form in the involuntary muscles along the walls of the stomach and intestine are called leiomyosarcoma. This type of cancer develops relatively slowly, but it will spread to other areas of the body once metastasis begins, and it can often be fatal.

Leiomyosarcoma Average Cost

From 367 quotes ranging from $3,000 - $8,500

Average Cost

$6,000

Symptoms of Leiomyosarcoma in Dogs

Finding the tumor early will give your dog the best chance of survival. If you notice any of the following signs in your dog discuss them with a veterinarian immediately:

  • Vomiting (often with blood)
  • Weight loss
  • Diarrhea
  • Lethargy
  • Abdominal pain or swelling
  • Palpable mass
  • Constipation
  • Tenesmus (tendency to clear the bowls often)
  • Blood in the stool (hematochezia)
  • Black tar-like stool with dried blood (melena)

Types

Neoplasia are defined by the type of cells on which they grow, as well as the place in the body where they are found, and whether the tumor is malignant (cancerous) or benign. There are several types of GI tumors which could be relevant to your dog’s diagnosis:

  • Adenocarcinoma – malignant tumor that forms on glandular cells and is the most common form of GI cancer found in dogs, making up 42 to 72% of the cases. It metastasizes very quickly.
  • Leiomyosarcoma – malignant tumor that forms in involuntary smooth muscles cells. As the second most common form of GI cancer found in dogs it makes up about 20 to 30% of cases. It normally metastasizes somewhat slower than adenocarcinoma.
  • Leiomyoma - the benign form of leiomyosarcoma. This is also a tumor of involuntary, smooth muscle cells, but it will rarely grow or migrate to other parts of the body. It is rare in dogs.

  • GISTs (GI Stroma Tumors) - another type of tumor which forms on the walls of the GI tract. It is based on nervous system cells called “interstitial cells of Cajal.” These cells control the involuntary muscles of the intestinal tract and are sometimes called the pace-makers of the GI. GISTs look a lot like leiomyosarcoma and historically the two have been confused; however recent studies in humans and dogs have shown differences which can be relevant to treatment and many more leiomyosarcoma are now diagnosed as GISTs. In dogs, GISTs are generally found in the large intestine rather than the stomach. GIST may refer to a malignant or benign tumor.
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Causes of Leiomyosarcoma in Dogs

It’s not known what causes leiomyosarcoma in dogs. The condition is more likely to develop in older dogs. As with humans, family medical history could indicate a predisposition, and environmental factors may play a part, but this is even more difficult to track with dogs. Among breeds, Belgian Shepherd’s are considered predisposed to form GI carcinoma such as adenocarcinoma, but leiomyosarcoma has not been identified as being especially common in any particular breed. 

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Diagnosis of Leiomyosarcoma in Dogs

Based on the symptoms, your veterinarian may suspect cancer of the stomach. Various imaging techniques will indicate the presence of a tumor including radiography with contrast, ultrasound, and endoscopy. An endoscopy involves inserting a tool down the throat, so your dog will need to fast for several hours and receive an anesthetic if this test is ordered.

Before recommending a treatment plan, the veterinarian will endeavor to find out as much as possible about the tumor. Standard procedure includes several radiographs of the thorax, an abdominal ultrasound, and full blood and urine tests. Hypoglycemia commonly develops with leiomyosarcoma, and blood or urine samples may also show if the cancer has spread to the liver. Occasionally the veterinarian may order a laparotomy or exploratory surgery to further analyze the tumor.

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Treatment of Leiomyosarcoma in Dogs

Surgery is the most common treatment for leiomyosarcoma. Of course, this will depend on the size of the tumor and whether or not it has spread. Depending on the results of your dog’s tests, the veterinarian may decide that the cancer has already progressed beyond the level of treatment and recommend euthanasia. Surgery can be risky, and if the cancer has spread more than was anticipated, it’s possible the dog may end up having to be euthanized in the process.

Surgery commonly involves removing part of the stomach or intestinal wall with the tumor, and reconnecting the two parts back together. Your dog will need to spend at least several days in a veterinary hospital after the surgery. Fluids will be administered through an IV as well as antibiotics to control infection and medication for vomiting.

Additional biopsies are usually performed during surgery and the removed tumor is analyzed to determine its level of aggressiveness more accurately.  This information can help to determine if further measures are necessary. Tumors which are removed cleanly with no signs of metastasis are usually not treated further. If the tumor was only partially removed, or there were signs of metastasis the veterinarian may recommend chemotherapy.

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Recovery of Leiomyosarcoma in Dogs

In the best case scenario, your dog will need to recover from major surgery. This can take two to three weeks. Your dog will need to limit activity. He will most likely be prescribed a pain reliever and often an antacid as well. You will need to check the incision daily for signs of tearing or infection, and he should also have a check-up with the veterinarian after several weeks.

If chemotherapy is prescribed, this usually will include a number of injections administered at two or three week intervals. Expect at least a 90 minute appointment each time for additional tests and monitoring. Dogs do not typically suffer hair loss, but they may have gastrointestinal side effects.

There are a number of studies tracking the post-surgery survival times for groups of dogs with leiomyosarcoma. Figures range from an average survival time of 10 months to close to 2 years. One dog was recorded as surviving for 7 years after surgery. The chances are higher if the surgery is completed before metastasis has begun. There aren’t a lot of statistics on the effectiveness of chemotherapy with leiomyosarcoma. There are a few successful cases, but other dogs have died from tumor related issues only a few months after treatment. There is a better chance of recovery from leiomyosarcoma than from more aggressive cancers like adenocarcinoma, but you should remain guarded about your dog’s prospects.

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Leiomyosarcoma Average Cost

From 367 quotes ranging from $3,000 - $8,500

Average Cost

$6,000

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Leiomyosarcoma Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Sully

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Flat Coated Retriever mix

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14 Years

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Mild severity

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0 found helpful

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Mild severity

Has Symptoms

Currently He Cries A Lot

2 years ago My dog was limping for 9 months when they finally found a small bump in between his pads on his left foot. It was surgically removed & the pathology said it was a leiomyosarcoma. Everything I’ve read says a leiomyosarcoma is in the stomach or intestines. Can it be on the leg or foot or might my dogs pathology have been incorrect?

April 29, 2018

Sully's Owner

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Dr. Michele K. DVM

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1611 Recommendations

That type of tumor is typically found in the GI tract, and to my knowledge, is an unusual tumor to find on the foot. Sarcomas in general may be histologically similar, though. Since you are not sure of the diagnosis, it would be quite acceptable for your veterinarian to call and talk to the pathologist to get a better idea of what they saw, especially if they weren't aware of the history when they were looking at the tumor.

April 29, 2018

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Bobo

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Jack Russell

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14 Years

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Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Weight Loss
Vomiting
Loss Of Appetite
Mass At Stomach Wall
Mass In Spleen

My dog had mass at her stomach wall and spleen. We are suspecting my dog had cancer , but unsure. The only way to find out is to do “fine needle aspirates”. My question is is that safe? If the cancer is a type of cancer that can spread, then will the cancer spread to other part of organ or body when the needle is contacted during the operation when the needle is insert into and pull out while retrieving the tissue sample?

Oct. 11, 2017

Bobo's Owner

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3320 Recommendations

Fine needle aspirates are a safe and relatively inexpensive procedure which may be performed by ultrasound guidance in cases which involve deep tissues. A fine needle aspirate is the first step taken before a biopsy or surgical excision is performed; there is some scaremongering online about this procedure but the procedure is routine and diagnostically valuable. Regards Dr Callum Turner DVM

Oct. 11, 2017

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Dakota

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American Cocker Spaniel

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7 Years

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

Cancer

My dog, Dakota had his spleen removed in February, due to a mass. It came back as Leiomyosarcoma. In March he developed pancreatitis. Yesterday he had to have needle aspirations in his liver, pancreas and stomach. They found cells consistent with Leiomyosarcoma. So the cancer has spread. What symptoms should I look for now? What is the estimated survival time?

July 26, 2017

Dakota's Owner

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3320 Recommendations

Unfortunately, leiomyosarcoma is aggressive and survival time is generally measured in months especially when metastasised to the liver; for a more accurate survival time, your Veterinarian would be able to give you more information regarding Dakota’s specific case. The progression of symptoms can be quite vague including vomiting, diarrhoea, jaundice, abdominal pain and weight loss. Regards Dr Callum Turner DVM

July 26, 2017

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Dakota

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Cocker Spaniel

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8

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Moderate severity

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Moderate severity

Has Symptoms

Coughing
Lumps Under Skin

My 8 yr old cocker spaniel has Leiomyosarcoma. They found it when they took his spleen out which had a 5-7 cm diameter mass. They also took 3 liver biopsies, pancreatic biopsy and a splentic lymph node was submitted for histopathology. 1. Ramdomly scattered clusters of hepatocytes swollen and have finely granular eosinphilic cytoplasm. sections of spleen have mult. infiltrative, poorly demarcarcated, unencapsulated masses that replace normal architecture. Masses are composed of cells that form intertwining streams and bundles w/small to moderate amounts of eosinophilic matrix. The cells are medium sized and fusiform w/indistinct cell borders. Nuclei are medium-sized and ovalto fusiform w/blunt ends. The mitotic index is 3. Areas of necrosis and hemorrhage associated w/the masses. Abnormal tissue extends into the mesentery but not to the margins of the specimen. Diagnosis: 1) Hydropic degeneration, mild, multifocal 2) Fat necrosis, focal, omentum 3) Nodular Hyperplasia, pancreas 4) Leiomyosarcoma, spleen. Primary lesion is the leiomyosarcoma in the spleen. Classified as a malignancy based on the multiple tumors and infiltration. Pancreas and omentum are likely incidental findings. The liver has some hydropic degeneration and is suggestive of steroid hepatopathy.

July 26, 2017

Dakota's Owner


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recommendation-ribbon

3320 Recommendations

Unfortunately I am not sure what your question is as all I see is a histopathology report which is comprehensive indicating the origin of the tumour and the condition of the liver. It seems like Dakota will need to have chemotherapy based on the results of the histopathology along with normal postoperative supportive care. Regards Dr Callum Turner DVM

July 26, 2017

I was hoping you could explain it to me in simple terms. Did they get all of the cancer or has the cancer spread, what does the mitotic index 3 mean? In this case what is the usual prognosis? They told me Chemo would not work on this cancer??? I am sorry to bother you but I want to understand and cannot get any one to explain this.

July 26, 2017

Dakota's Owner

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Dakota

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Cocker Spaniel

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8 Years

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Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Spleen Mass

What is the average survival time for Leiomyosarcoma when the spleen was removed? Does Leiomyosarcoma respond to any type of chemotherapy, if so which one? My vet is not familiar with this cancer. Thank you!

July 26, 2017

Dakota's Owner

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recommendation-ribbon

3320 Recommendations

Survival time can vary widely from a month to four years, the median survival time is less than a year. Chemotherapy that is commonly used would be a combination therapy of doxorubicin, cyclophosphamide and vincristine. If you have any concerns, a visit to a Specialist may be useful. Regards Dr Callum Turner DVM

July 26, 2017

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Stitch

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Mix

dog-age-icon

10 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Vomitting,
Loss Of Motivation To Eat

Dear Dr, My dog, Stitch, recently had an urgent surgery due to swelling belly. They removed a huge tumor from her belly. They mentioned that they have not seen metastasis and the other organs were fine as well. The biopsy result of the tumor has been arrived recently and it says leiomyosarcoma, intestine and associated mesentery. We have an urgent appointment for the onco vet tomorrow (19 Apr) in order to discuss what the next steps are to give the best treatment to my dog. The vet told me (who removed the tumor) that it might be that another surgery is needed to remove the part of the intestine from where the tumor has grown to ensure that there is no cancer cells left. And after maybe chemo will be administered as well depending on what the onco vet will see in her. My question would be: based on your experience what would be your recommendation to Stitch? Thank you for the reply in advance, Molli

Leiomyosarcoma Average Cost

From 367 quotes ranging from $3,000 - $8,500

Average Cost

$6,000

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