Is There Medication To Shrink Tumors In Dogs?

Dogs can develop various types of tumors, some benign and some malignant. Just like in humans, tumors in dogs can form as a result of abnormal cell growth. When cells grow uncontrollably, they can form masses or lumps called tumors. Tumors can develop anywhere in a dog’s body – on the skin, in organs, etc. Some common tumors found in dogs include mast cell tumors, melanoma, soft tissue sarcomas, osteosarcoma, and mammary gland tumors.

While some tumors are harmless, others can be cancerous or otherwise problematic for the dog’s health. Therefore, detecting and diagnosing tumors early is important. Treatment options depend on the type of tumor, its location, and whether it is benign or malignant. Options may include surgical removal, chemotherapy, radiation therapy, or medication to shrink tumors. This article will provide an overview of the key considerations around medications to shrink tumors in dogs.

Types of Tumors in Dogs

Tumors can be broadly categorized as either benign or malignant. Benign tumors are non-cancerous growths that tend to grow more slowly and don’t typically spread to other tissues in the body. However, some benign tumors can still be life-threatening if they grow large enough to impede vital organs or functions. Some of the most common benign tumors in dogs include lipomas (fatty tumors), adenomas (tumors of glandular tissue), and papillomas (wart-like growths).

Malignant tumors are cancerous and have the ability to invade nearby tissue and spread to other parts of the body. Examples of malignant tumors that commonly affect dogs include mast cell tumors, melanoma, osteosarcoma, and lymphosarcoma (lymphoma). These types of cancers can be very aggressive and require intensive treatment. According to one source, malignant lymphoma is one of the most common types of tumors in dogs.

Some of the most common warning signs of tumors in dogs include lumps or bumps on or under the skin, unexplained weight loss, loss of appetite, lethargy, and limping or lameness. It’s important to have any new lumps or bumps evaluated by a veterinarian, as early detection is key for successful treatment. Biopsies are usually needed to diagnose whether a tumor is benign or malignant.

Diagnosing Tumors

If a tumor is suspected, the vet will first perform a complete physical exam on the dog. They will check for any lumps, bumps, or abnormalities on the skin or inside the mouth. The vet will also palpate the dog’s abdomen, chest, and legs to feel for masses or enlarged organs. If an internal tumor is suspected, the vet may order imaging tests like x-rays, ultrasound, CT scan or MRI to get a closer look at the organs and detect masses. These imaging tests allow the vet to see the location, size and shape of a suspected tumor.

To determine if a growth is cancerous, the vet will need to take a sample of the tumor cells or tissue and examine it under a microscope. This is called a biopsy. There are a few different types of biopsies the vet may use depending on the location of the tumor. A fine needle aspiration uses a small needle to extract cells from the tumor. An incisional or excisional biopsy involves surgically removing a piece of the tumor for testing. These allow the vet to determine exactly what type of cancer the dog has so they can plan the most effective treatment.

Accurate diagnosis through physical exam, imaging and biopsy is key to creating the right treatment plan for a dog’s cancer. Knowing the type of tumor and how advanced it is will inform what medications or therapies may help shrink it.


Treatment Options

There are several main treatment options for shrinking or removing tumors in dogs:


Surgical removal of the tumor is a common treatment when the tumor is localized and has not spread. Surgery aims to fully remove the tumor and surrounding tissue margins to prevent recurrence. According to Hill’s Pet, surgery can successfully treat many types of cancerous tumors in dogs when caught early.


Chemotherapy uses anti-cancer drugs to kill cancer cells and shrink tumors. It may be used before surgery to shrink large tumors to a removable size, or after surgery to kill any remaining cancer cells. Chemotherapy can also be used as a standalone treatment for inoperable tumors. Different chemotherapy drugs are used depending on the type and location of the tumor.


Radiation focuses high energy x-rays on the tumor to damage cancer cell DNA and cause cell death. It may be used alone or with chemotherapy to shrink tumors before or after surgery. Radiation can target tumors that cannot be completely removed through surgery. Side effects of radiation depend on the area being treated.

Medications to Shrink Tumors

There are a few medications available that can help shrink or slow the growth of tumors in dogs. Here is an overview of some of the most common oral medications used:

Toceranib phosphate (Palladia) – This is an oral chemotherapy drug that targets specific receptors on tumor cells and blood vessels to inhibit tumor growth and angiogenesis. It is most effective when combined with other treatments like surgery and radiation. Studies have shown toceranib can stabilize disease and extend lifespan in dogs with a variety of cancers including mast cell tumors, carcinoma, and sarcoma. Side effects can include gastrointestinal issues and neutropenia.

Oclacitinib (Apoquel) – While not a cancer drug itself, oclacitinib is an immunosuppressant that can help control inflammation and pruritus associated with certain tumors like cutaneous mast cell tumors. By reducing inflammation, it may inhibit tumor growth and metastasis. More research is still needed on its direct anti-tumor effects.

Chlorambucil – This alkylating agent has been used as chemotherapy for lymphoma and other cancers in dogs. It works by damaging the DNA of cancer cells, leading to cell death. Chlorambucil is given orally but side effects can include bone marrow suppression.

Cyclophosphamide – Another alkylating chemotherapy drug that interferes with cancer cell growth. It is used to treat lymphoma, leukemia, multiple myeloma, and some solid tumors. Cyclophosphamide has more severe side effects than chlorambucil, including bleeding, infection, and bladder toxicity.

Some natural supplements like turmeric, CBD oil, and I’m-Yunity may help with inflammation, pain, and slowing tumor progression. However, more research is still needed on their anti-tumor effects in dogs. It’s important to discuss any supplements with your veterinarian.

In most cases, medication alone is not curative. But it can be an important part of a multimodal treatment plan when combined with surgery, chemotherapy, radiation therapy, etc. Work closely with your vet to determine the most effective options for your dog.



Chemotherapy involves using anti-cancer drugs to treat cancer in dogs It works by stopping or slowing the growth of cancer cells. Chemotherapy is commonly used to treat a variety of cancers in dogs including lymphoma, mast cell tumors, osteosarcoma, and hemangiosarcoma.

Some of the chemotherapy drugs used for dogs include:
– Vincristine

– Cyclophosphamide
– Doxorubicin

– Cisplatin
– Carboplatin

Chemotherapy is typically given by intravenous injection or oral medication. The frequency and duration of treatments depends on the type of cancer. Cycles of chemotherapy are often given every 2-3 weeks over a period of months. Dogs receive chemotherapy treatments on an outpatient basis, allowing them to recover at home between treatments.

Chemotherapy has risks of side effects like nausea, vomiting, diarrhea, and suppression of the immune system. However, medications can help control nausea and veterinarians monitor blood cell counts closely during chemotherapy. Overall, most dogs tolerate chemotherapy well if properly monitored.

Side Effects

Chemotherapy has many potential side effects in dogs, though the severity and duration varies between medications. Some of the most common side effects of chemotherapy in dogs include:

Appetite loss: Chemotherapy frequently causes decreased appetite due to nausea. This can lead to weight loss if not properly managed with medications and dietary changes.1

Nausea: Nausea and vomiting are common side effects of chemotherapy in dogs. Anti-nausea medications are typically prescribed to help manage these symptoms.2

Hair loss: Certain chemotherapy drugs frequently cause alopecia (hair loss) in dogs, though the hair regrows once treatment is completed. Breeds with continuously growing hair are more prone to noticeable hair loss.3

Costs of Treatment

Treating dog tumors can be very expensive, often costing thousands of dollars. The main costs associated with tumor treatment in dogs include:

Surgery – Surgical removal of tumors is often the first line of treatment. The cost of surgery can range from $1,500 to over $5,000 depending on the type of tumor, location, complexity of the procedure, and whether it’s done at a specialty center. According to Forbes, the average cost of tumor removal surgery for dogs is around $2,500.

Medications – Medications like chemotherapy and anti-inflammatory drugs are commonly used to treat dog tumors. A standard course of chemotherapy costs $3,000 – $5,000. Newer targeted cancer drugs can cost over $6,000 for a full treatment protocol. Medications to manage side effects add to the costs.

Vet bills – Frequent vet visits for consultations, lab tests, imaging, hospitalization and post-op care can quickly add up. Emergency vet care for complications can cost thousands. According to Healthy Paws Pet Insurance, the total cancer treatment cost for a dog often exceeds $10,000.

Pet insurance, payment plans, or assistance programs can help manage the high costs of treating dog tumors. But owners should be prepared for significant expenses, especially with aggressive treatments like chemotherapy or radiation therapy.

Outlook and Prognosis

The outlook and prognosis for dogs with tumors depends on several factors, including the type, size, and location of the tumor. Some key points on prognosis include:

  • The prognosis for dogs with malignant tumors that have spread (metastasized) is generally poor. Survival times range from weeks to months in most cases.
  • For dogs with non-metastatic masses that are surgically removed, the prognosis is often good if clean margins are achieved. Up to 50-60% of dogs can be cured with surgery alone.
  • Brain tumors often carry a grave prognosis, with most dogs surviving less than 3-4 months even with treatment. However, some types like meningiomas can have better survival times if caught early.
  • With hemangiosarcoma, a common malignant tumor, median survival is around 3-6 months depending on the location.

In addition to survival times, quality of life is an important consideration for dogs with cancer. Maintaining good nutrition, managing pain, and treating other symptoms are key to ensuring the best possible welfare.


Preventing tumors in dogs can be challenging, but there are some steps pet owners can take to lower the risk. Getting your dog routine wellness exams with your veterinarian is crucial for early detection of any health issues, including tumors. Annual exams give your vet a chance to thoroughly inspect your dog and get to know what is normal for them. This makes it easier to identify any abnormalities that may indicate a developing tumor (Source).

Early detection of tumors greatly improves the chances of successful treatment. In addition to exams, being alert to any changes in your dog like lumps, limping, difficulty eating, or behavioral shifts can catch tumors when they are small and more treatable. Open communication with your vet and alertness to subtle changes are key prevention measures (Source).

While not fully preventable, steps like maintaining your dog at a healthy weight, feeding a nutritious diet, avoiding carcinogens, and limiting sun exposure may also lower tumor risk. Prevention starts with routine veterinary care to detect tumors early when treatment is most effective.

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