Causes Of Mast Cell Tumors In Dogs
The underlying causes of mast cells tumors are not known. Like other types of cancer, its likely they are caused by a mix of genetic and environmental factors, but we do not have enough information to recommend any changes to your dogs environment to prevent mast cells tumors.
Certain breeds, however, are more likely to get mast cell tumors. These include:
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Retriever breeds
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Rhodesian Ridgeback
A Quick Guide To Mast Cell Tumors In A Dog
A skin lump may be harmless, or it may be a serious tumor in progress.
Mast cell tumors are a vast topic because of their variable appearance and unpredictable nature. So, drawing in a deep breath, lets start at the beginning.
Mast cell tumors most commonly occur on the skin and now things start to get complicated.
The problem with these tumors is that they are the great pretenders. A dog may develop a simple, raised pink lump on his skin that has all the physical characteristics of being harmless, and yet when it is removed and analyzed, it turns out to be a highly aggressive cancer.
And not all mast cell tumors are the same. Indeed, they are graded 1 to 3 in terms of nastiness .
Many mast cell tumors fall into the middle group , which have a foot in either camp. The problem here is making a decision of whether to put the pet through radical surgery or potentially harmful chemotherapy on the basis of what might happen.
Unfortunately, some breeds are more likely to get mast cell tumors, including Golden Retrievers, Boxers, the bull breeds and Boston Terriers.
What Is A Mast Cell Tumor In Dogs
A mast cell tumor , also known as mastocytoma, is a specific type of skin cancer that stems from mast cells. Mast cells are white blood cells that can be found in several tissues and play a major role in allergic reactions.
As a skin cancer, the mast cell tumor dog causes lumps and bumps that can imitate literally any skin lesion. Therefore, in a 2017 Frontiers study, Are Mast Cells MASTers in Cancer?, mast cell tumors in dogs are metaphorically compared to masters.
Mast cell tumors are aggressive and tend to invade surrounding tissues. Also, although most common on the skin, the mast celldog tumor can grow in other locations like the liver, bone marrow, and intestine.
If the dogs body is entirely affected by mast cell tumors, the condition is known as mast cell disease or canine mastocytosis.
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Diagnosis Of Mast Cell Tumors
The initial evaluation of a suspected MCT begins with a fine needle aspirate and cytology, from which a diagnosis is usually made. Grading of the tumor cannot be done at this point as only cells are obtained from the aspirate visual examination combined with the cytology report will determine if the MCT is a candidate for surgical excision.
It is reasonable to stage the tumor prior to surgery in cases of a recurring tumor, multiple tumors, or evidence of metastasis, staging in advance is considered necessary.
When an MCT spreads, the cancer usually moves into the regional lymph nodes near the tumor, then to the liver and spleen it can also spread to other places in the abdomen as well as to the bone marrow. At a minimum, the staging tests should include an aspirate of the lymph nodes near the tumor and an abdominal ultrasound.
The ultrasound can show if there is any evidence of metastasis or anything suspicious that requires further testing. Aspirates of the liver and spleen may be recommended, even if all the organs appear normal, because they may harbor cancer cells.
Tumor Grade Vs Tumor Stage What Do They Mean
Canine mast cell tumors are classified by grade and stage. This helps your veterinarian decide how to best treat your dog.
Tumor GRADE:
How aggressive the tumor is and how likely it is to spread?
Mast cell tumors are graded from 13 or low to high. Grade 1 tumors are the least likely to spread to other areas of your dogs body and grade 3 or high-grade being the most likely to spread and have the highest chance of reccurring.
Tumor STAGE:
How much has the cancer already spread?
There are four stages of mast cell tumors. Stage 1 has not yet begun to spread and Stage 4 is the most advanced.
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Symptoms Of Mast Cell Tumors
Mast cell tumors may not cause any symptoms at all. To help prevent more serious disease, vets recommend checking your dog every few months to look for any masses on the skin. Make an appointment to see your vet if you find:
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A new skin mass
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A known mass that has changed in size or color
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An unexplained allergic reaction or hive
Some masses may appear small and easily movable in the skin with little swelling. More aggressive tumors can appear as larger, hairless sores.
In some cases, however, a mast cell tumor will result in symptoms, including strong allergic reactions triggered by the activated immune system. Also, if a tumor is bumped or agitated, it may go through a process called degranulation. This means the tumor releases all its inflammatory material at once. Degranulation can cause symptoms such as swelling and redness in the affected area or a more severe anaphylactic reaction that includes:
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Swelling of the face and limbs
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Collapse and death
What Are The Signs That My Dog May Have A Mast Cell Tumor
Mast cell tumors of the skin can occur anywhere on the body and vary in appearance. They can be a raised lump or bump on or just under the skin, and may be red, ulcerated, or swollen. While some may be present for many months without growing much, others can appear suddenly and grow very quickly. Sometimes they can suddenly grow quickly after months of no change. They may appear to fluctuate in size, getting larger or smaller even on a daily basis. This can occur spontaneously or with agitation of the tumor, which causes degranulation and subsequent swelling of the surrounding tissue.
When mast cell degranulation occurs, some chemicals and compounds can go into the bloodstream and cause problems elsewhere. Ulcers may form in the stomach or intestines, and cause vomiting, loss of appetite, lethargy, and melena . Less commonly, these chemicals and compounds can cause anaphylaxis, a serious, life-threatening allergic reaction. Although very uncommon, MCTs of the skin can spread to the internal organs, causing enlarged lymph nodes, spleen, and liver, sometimes with fluid build-up in the abdomen, causing the belly to appear rounded or swollen.
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How Can I Spot A Canine Mast Cell Tumor
Bathing your dog or even giving them belly scratches and cuddles is a good opportunity to look for lumps and bumps. If anything looks suspicious, bring it to the attention of your veterinarian. Its better to identify MCTs when theyre small so even if you think it might just be a bug bite, it never hurts to get a professional opinion.
Case Selection And Study Design
Medical records of client-owned dogs that were presented to the University of Georgia Veterinary Teaching Hospital for surgical excision of an MCT or STS over a continuous period from January 1, 2014, to July 31, 2019, were evaluated. Dogs were included when the following criteria were met: a diagnosis of either MCT or STS was made on the basis of histopathologic findings, surgical excision was performed at the University of Georgia Veterinary Teaching Hospital, and follow-up information was available 30 days after surgery. Scar revisions, radical excisions, and dogs that underwent multiple surgical excisions within the allotted time were included, as this represented a large proportion of cases treated at this tertiary specialty center. Dogs with multiple concurrent MCTs, subcutaneous MCTs, or concurrent MCTs and STSs were also included.
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When Do You Stop Fighting Mast Cell Tumors In Dogs
As you can see, the prognosis and life expectancy can vary significantly. For some dogs, a mast cell tumor is just a one-time problem that surgery can quickly and completely resolve. But other dogs arent so lucky. Maybe they have an aggressive tumor which is causing local or systemic effects. Or they have one that is difficult to remove surgically or requires additional therapies. In those situations it can be hard to know when you should stop fighting the mast cell tumor.
I cant answer the question of when to stop fighting mast cell tumors for your dog. But I can help direct you to some people who might be able to give you support and a bit of clarity. First of all, your veterinarian or veterinary oncologist are great resources. Like you, they are committed to helping provide your dog a good quality of life. They can help you evaluate your dog and discuss options for improving quality of life. Or they can help you know when it is time to say goodbye to your dog and prepare for your dogs euthanasia.
You could also consider consulting with a veterinarian who specializes in dog hospice care. These wonderful individuals can help fill your dogs last days with dignity and comfort. And they too can help you decide when to stop fighting mast cell tumors.
Mast Cell Tumors In Dogs: What Dog Parents Must Know
Dr. Julie Buzby
Mast cell tumors in dogs are masters of disguise and can sometimes have serious consequences for a dogs health. To teach you more about these tricky tumors, integrative veterinarian Dr. Julie Buzby shares the the symptoms, diagnosis, treatment, and prognosis for mast cell tumors.
You may have found a small mass on your dog that seems to have appeared overnight. Or maybe the mass had been there for years. But suddenly it looks red and swollen and now your dog wont stop licking it. Or perhaps you didnt even know your dog had a mass until your veterinarian found it during a routine physical exam.
All of these scenarios could have the same troubling diagnosisa mast cell tumor. This is the most common skin mass in dogs, and a mast cell tumor diagnosis opens a can of worms.
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Potential Mechanism Of Action
All tested canine patients responded to the viral treatment completely or partially. What mechanism enabled the response? Sendai virus could specifically destroy malignant cells via a number of mechanisms outlined in two recent reviews and briefly summarized here.
Direct Destruction of Cancer Cells
One of the possible mechanisms of Sendai virus anticancer activity involves a selective direct destruction of cancer cells. This destruction is most likely promoted by higher affinity of Sendai virus to malignant rather than to normal cells and by the ability of Sendai virus to form syncytia.
Sialic acid polymers are cellular receptors for some paramyxoviruses including Sendai virus . The virus has high affinity for its receptor. This high affinity toward sialic acid polymers promotes better binding of Sendai virus to malignant rather than to normal cells because density of sialic acid polymers on the cellular surface correlates with cellular malignancy .
Sendai virus, like other Paramyxoviruses, is able to spread through formation of large multinucleated structures. By inducing fusion of infected and uninfected cells the virus efficiently spreads without being exposed to neutralizing antibodies. The cell fusion structure, the syncytium, has a survival time of < 5 days . A tumor cell, which is fused into a syncytium, cannot survive longer.
Unmasking Cancer Antigens
Stimulation of Natural Killer Cells
Stimulation of Dendritic Cells
Stimulation of Interferons
Grading Of Mast Cell Tumors In Dogs
Grading refers to a description of a tumor, designed to predict how it will behave, such as whether it will remain localized or spread throughout the body. Once the tumor is biopsied, the pathologist can determine the grade of the tumor based on location, presence of inflammation, and how well the cells are differentiated . The more differentiated the cells are, the better the prognosis.
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Grade 1 Cells are well-differentiated. 25% recurrence rate. Low chance of metastasis.
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Grade 2 Moderately differentiated. 44% recurrence rate. Potential for locally invasive metastasis.
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Grade 3 Poorly differentiated. 76% recurrence rate. High potential for metastasis.
Additionally, the pathologist will examine the MCTs mitotic index, which assesses how quickly the cancerous cells are multiplying. Mast cell tumors with a low mitotic index have a better prognosis than those with a high index.
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Stages Of Mast Cell Tumors In Dogs
The stage of the tumor refers to how much it has spread. Symptoms of MCT may vary depending on the stage of the disease:
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Stage I Single tumor without metastasis.
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Stage II Single tumor with metastasis into the surrounding lymph nodes causing secondary growth.
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Stage III Multiple skin tumors, or a large tumor that has invaded the subcutaneous tissues. There may or may not be lymph node involvement.
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Stage IV Presence of one or more tumors with metastasis in the skin and possibly other organs. Lymph nodes will be involved.
Factors That Affect Lipomas
Fatty tumors usually occur in older and more obsess dogs. Hence, a healthier diet and more exercise can help prevent them. Changing your dogs diet to have more proteins and less carbodydrates can work. You can reduce carbs over time and introduce more protein on a rolling basis. This way the dog can feel more comfortable shifting its diet.
You can also reward good behavior like staying clean with treats. However, make sure that if your dog becomes dirty, the dog isnt rewarded at all. Once the dogs weight is reduced, the Lipomas may also disappear.
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Recovering From Mast Cell Tumors
Recovering from surgical removal of a low-grade mast cell tumor usually requires 2 weeks of rest, pain medications, antihistamines like Benadryl, and wearing an e-collar . After 2 weeks, your veterinarian will remove the sutures and your dog can resume normal activity.
For several months after surgery, its important to watch the area where the mass was removed to see if it comes back, although recurrence is unlikely for most low-grade tumors. Surgery in most cases is curative, and a dog usually will be able to live their natural lifespan.
For high-grade tumors, recovery after surgery will be the same, but your veterinarian will likely suggest pursuing additional treatment such as radiation or chemotherapy to prevent any tumors or cancer cells that have spread from causing more problems.
Survival with radiation or chemotherapy usually ranges from 10 months to 2 years, depending on the tumor and the therapy. Without any treatment, survival averages about 4 months.
Mct Grade And Outlook
Low grade tumours and around 75% of intermediate tumours are cured with complete surgical excision. Unfortunately, most high grade tumours and around 25% of intermediate grade tumours have already spread by the time they are diagnosed . These cases are likely to benefit from additional medical treatment. In some dogs, further analysis of the biopsy samples is useful in determining the best management options.
The tumour grade is very important in determining the appropriate therapy for dogs with MCTs.
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How Does This Cancer Typically Progress
This tumor’s behavior is complex and depends on many factors. Typically, when the tumor cells are examined under a microscope, the pathologist can assess how aggressive the cancer is based on several criteria. The tumor as a whole is graded from I-III, with grade I as much less aggressive than grade III MCTs. Higher grade tumors have a higher tendency to metastasize .
Typically, the prognosis is less favorable if:
- the patient is one of the susceptible breeds
- the MCT is located at a junction where the skin meets mucous membranes
- when viewed under the microscope, the number of cells actively replicating is high
How Are Mast Cell Tumors Treated
Surgery for lower-grade tumors provides the best long-term control
In lower-grade tumors with no evidence of spread, surgery is likely the best option. Surgery for lower-grade tumors provides the best long-term control, with chemotherapy rarely required. However, in higher-grade tumors, even without evidence of spread, a combination of surgery and chemotherapy is often recommended. Radiation therapy is another option if the mass is not in a suitable location for surgical removal or if the surgical removal is incomplete .
Given that it is now known there is an underlying genetic basis for MCT, drugs such as toceranib phosphate are being designed to target the proteins associated with the development of cancer. In patients with non-surgical MCT, or recurrent MCT that has failed to respond to other chemotherapies, targeted therapy becomes a much more appealing option. A veterinary oncologist is the best resource for determining what is best for your dog.
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Mast Cell Tumors Faqs
What is the survival rate for dogs with mast cell tumors?
Survival rate depends on the grade of the mast cell tumor. There are multiple grading systems, but they can be broken into less aggressive tumors call low grade and more aggressive tumors called high grade.
For low-grade mast cell tumors, surgical removal may be curative. There is a small chance of recurrence, but most dogs will live out their natural lives after removal. For high-grade mast cell tumors the survival time with surgery alone is only about 4 months.
If additional treatment such as radiation therapy or chemotherapy is performed, the average survival time increases to 1 year or more. The survival rate for high-grade tumors can vary significantly due to the treatment option selected and the individual nature of the tumor.
Are mast cell tumors in dogs always cancerous?
All mast cell tumors are considered cancerous so any identified mast cell tumor should be surgically removed if possible. This does not mean that all mast cell tumors will metastasize or that all mast cell tumors will require chemotherapy. These factors depend on the grade of tumor at the time of removal.
How serious are mast cell tumors in dogs?
Mast cell tumors are quite serious when identified in dogs. If untreated they can cause anaphylactic shock or if they progress into a more aggressive form they can metastasize and ultimately lead to death.
How much does it cost to remove a mast cell tumor from a dog?
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