As a holistic veterinarian, I’ve had countless conversations with worried pet parents about mast cell tumors in dogs. These growths are one of the most common types of skin cancer in dogs, and they can vary from mild to very serious. Let’s walk through what they are, how they’re diagnosed, and the treatment options available so you can make the best choices for your dog’s care.
What Are Mast Cell Tumors?
Mast cell tumors develop when mast cells, which are part of your dog’s immune system, start multiplying out of control. Mast cells normally help with allergic reactions and inflammation, but when they grow abnormally, they can form tumors anywhere on the body, most often on the skin.
Some mast cell tumors stay small and localized. Others are more aggressive and can spread (metastasize) to other parts of the body such as the liver, spleen, or lymph nodes. Because these tumors can look very different from one dog to another, it’s important to have any new lump checked by your veterinarian.
Signs and Symptoms to Watch For
Mast cell tumors can look like almost anything, which makes them tricky to identify at home. They may be:
- Small or large
- Firm or soft
- Hairless or covered with fur
- Red, swollen, or occasionally ulcerated (open and sore-looking)
Sometimes these lumps grow and shrink in size, which is a key clue. You might also notice:
- Itching or irritation at the lump site
- Loss of appetite
- Vomiting or diarrhea
- Lethargy or unusual tiredness
Any lump that changes rapidly or causes discomfort should be examined as soon as possible. Early detection is the best way to protect your dog’s long-term health.
What Causes Mast Cell Tumors?
The exact cause isn’t fully understood, but both genetics and environment play a role.
Genetic and Environmental Factors
Some dogs are genetically predisposed. Exposure to toxins, radiation, or chronic inflammation may also increase risk. A healthy immune system and a clean environment can help reduce risk factors where possible.
Breeds at Higher Risk
Mast cell tumors can affect any dog, but they are seen more often in:
- Boxers
- Boston Terriers
- Labrador Retrievers
- Beagles
- Schnauzers
They’re also more common in middle-aged and older dogs. While being in a higher-risk group doesn’t mean your dog will definitely get a mast cell tumor, it’s a reason to stay vigilant about skin checks.
How Mast Cell Tumors Are Diagnosed
If you bring your dog in for a lump or bump, here’s how we typically move forward.
Fine Needle Aspiration (FNA)
This simple, minimally invasive test involves inserting a tiny needle into the lump to collect cells. Most dogs tolerate it very well, and no anesthesia is needed. The sample is then examined under a microscope to check for mast cells.
Additional Testing
If mast cells are found, your vet may recommend:
- Bloodwork (CBC and chemistry panel): to assess overall health and organ function
- Urinalysis: to detect other underlying issues
- Imaging (ultrasound or X-rays): to check whether the tumor has spread
Staging the Tumor
Once confirmed, staging helps determine how far the tumor has progressed. This guides treatment and helps predict prognosis.
Staging system for mast cell tumors in dogs:
- Stage 0: Single tumor, completely removed, no spread
- Stage I: Single tumor, no lymph node involvement
- Stage II: Single tumor with spread to nearby lymph node
- Stage III: Multiple skin tumors or one large invasive tumor (may or may not involve lymph nodes)
- Stage IV: Any tumor that has spread to distant organs such as the liver, spleen, or bone marrow
Knowing the stage allows us to create a targeted plan for your dog’s care and recovery.
Treatment Options for Mast Cell Tumors
Treatment depends on the tumor’s grade, size, and location, as well as your dog’s age and overall health. Most dogs benefit from one or more of the following:
1. Surgery
Surgery is usually the first step. The goal is to remove the tumor completely along with a small margin of healthy tissue to make sure no cancer cells remain.
After surgery, the tissue is sent to a lab to confirm that all cancerous cells were removed. Recovery typically takes a few weeks, and your dog may need pain medication and antibiotics.
In some cases, like when the tumor is in a difficult area such as the face or leg, complete removal isn’t possible and other treatments may be needed.
2. Chemotherapy
If the tumor has spread or can’t be fully removed, chemotherapy can help control the disease. These medications target rapidly dividing cells, including cancer cells. They can be given orally or by injection.
Side effects can include fatigue, loss of appetite, or mild nausea, but most dogs handle treatment better than people expect.
3. Radiation Therapy
Radiation uses targeted beams of energy to destroy cancer cells. It’s often used after surgery to kill any remaining tumor cells or when surgery isn’t an option.
Radiation requires multiple sessions over several weeks, but it can be very effective for local control.
4. Cold Laser Therapy and Holistic Support
Cold laser therapy (also called photobiomodulation) can reduce pain, swelling, and inflammation after surgery or during recovery. I often use it to support healing and comfort in my patients.
Holistic care can also make a difference. Nutritional support, natural anti-inflammatories, and immune-boosting supplements can help your dog stay strong during and after treatment.
You can schedule an online holistic consultation if you’d like to discuss personalized diet and supplement support for your dog.
Understanding Prognosis
The prognosis depends largely on tumor grade, which describes how aggressive the cancer cells appear under the microscope.
- Grade I: Low-grade, often cured with surgery
- Grade II: Intermediate behavior, may require follow-up care
- Grade III: High-grade and aggressive, more likely to spread
Other factors that affect prognosis include:
- The tumor’s size and location
- Whether it was fully removed
- Your dog’s overall health and immune function
Remember, grading gives a general outlook but doesn’t predict every outcome. Some dogs do very well with treatment and live long, happy lives.
Caring for a Dog with Mast Cell Tumors
Once your dog has been diagnosed, ongoing care and lifestyle adjustments can help improve comfort and quality of life.
At-home care tips:
- Feed a nutrient-dense, whole-food diet to support the immune system
- Keep stress low and provide gentle exercise
- Stick to a consistent schedule for any prescribed medications
- Schedule regular check-ups to monitor for recurrence or new growths
- Ask about cold laser therapy to support comfort and recovery
Your love, attention, and consistent care make a huge difference. With the right support and close monitoring, many dogs live comfortably for years after diagnosis.
Final note: If you find a new lump or bump on your dog, don’t panic but don’t wait either. Have it checked by your vet right away. Early action gives your pet the best chance for a healthy, happy life.
For holistic treatment guidance, nutrition planning, or cold laser therapy recommendations, you can book an online consultation with me at Journeys Holistic Veterinary Services.
Frequently Asked Questions
Mast cell tumors are one of the most common types of skin cancer in dogs. They begin in mast cells, which are part of your dog’s immune system and help with allergic reactions. These tumors can form anywhere on the body but are most often found on the skin.
The most common sign is a lump or bump on your dog’s skin that may grow or shrink in size. Some dogs also develop redness, swelling, or irritation around the lump. Other symptoms can include loss of appetite, vomiting, or tiredness, especially if the tumor releases histamine into the body.
Diagnosis usually starts with a fine needle aspiration, where a small sample of cells is taken from the lump and examined under a microscope. If mast cells are found, your vet may recommend further tests such as a biopsy, bloodwork, X-rays, or an ultrasound to see if the cancer has spread.
Treatment depends on the tumor’s size, location, and grade. Surgery is often the first step to remove the tumor completely. In some cases, radiation or chemotherapy may be added to prevent regrowth or spread. Supportive care such as cold laser therapy and nutritional supplements can help with recovery and overall well-being.
The outcome varies based on how advanced the tumor is. Low-grade tumors caught early and removed completely often have an excellent prognosis. High-grade or aggressive tumors may require additional treatment and closer monitoring. With the right combination of medical and holistic care, many dogs go on to live full and comfortable lives.
