Cancer is one of the most challenging health issues our canine companions can face. Just like in people, veterinary oncology has advanced significantly over the past decade, offering more precise ways to diagnose and treat a wide variety of tumors—often with the goal of not just extending life, but preserving the quality of that life.

For families navigating a pet cancer diagnosis, decisions about treatment involve weighing tumor behavior, expected outcomes, possible side effects, and what matters most in your pet’s daily experience. At Boundary Bay Veterinary Specialty Hospital (BBVSH) in Bellingham, our board-certified veterinary oncologists approach these decisions with clinical rigor and deep respect for each pet’s comfort, dignity, and joy.

That thoughtful approach is why we have chosen to offer Gilvetmab®, a newly available immunotherapy for dogs with mast cell tumors and melanoma. After careful review of the available evidence and real-world clinical experience, our oncology team believes Gilvetmab® can play a meaningful role in managing these cancers—especially for patients where systemic treatment is needed and where quality of life remains a central priority.

What Is Gilvetmab®?

Gilvetmab® is the first and only immune checkpoint inhibitor developed specifically for dogs with:

• Stage I, II, and III mast cell tumors (MCTs)
• Stage II and III melanoma

Rather than directly damaging cancer cells, Gilvetmab® works by supporting your dog’s own immune system—helping it recognize cancer cells that would otherwise go unnoticed.

This approach, known as immunotherapy, reflects a growing shift in cancer medicine toward treatments that partner with the body’s natural defenses. Similar strategies have been used for years in human oncology and are now becoming an important part of veterinary cancer care, as supported by organizations such as the Veterinary Cancer Society and resources like the Merck Veterinary Manual.

How Gilvetmab® Works

Cancer cells are skilled at avoiding detection.

Under normal circumstances, immune cells called T lymphocytes (often shortened to T cells) constantly scan the body for abnormal cells, including cancer. Some cancer cells protect themselves by using a biological “off switch” that tells the immune system to stand down. This process involves a pathway called PD-1 / PD-L1, which essentially puts the brakes on immune activity.

Gilvetmab® is a monoclonal antibody, meaning it is a highly targeted, laboratory-designed protein. It binds to the PD-1 receptor on canine immune cells, blocking the signal that cancer cells use to suppress immune function.

When this signal is interrupted:

• T cells are no longer switched off
• The immune system regains its ability to recognize cancer cells
• The body can begin attacking tumor cells more effectively

In practical terms, Gilvetmab® helps remove the cancer’s ability to “hide,” allowing the immune system to re-engage.

Why Our Oncologists Have Adopted Gilvetmab®

Our oncology team does not adopt new treatments lightly. Gilvetmab® stood out because it offers:

• A targeted mechanism, rather than broad damage to healthy cells
• A systemic effect, meaning it can address cancer throughout the body
• Encouraging tolerance in field studies involving dogs with mast cell tumors and melanoma
• No special handling requirements at home, unlike many chemotherapy medications

Clinical studies have demonstrated a reasonable expectation of efficacy along with a preliminary safety profile, showing reduction in solid tumor burden in dogs with eligible stages of disease. While Gilvetmab® currently carries a conditional product license—meaning long-term data collection is ongoing—our specialists feel it provides an important option when thoughtfully matched to the right patient.

What to Expect During Treatment

Administration

• Gilvetmab® is given intravenously (through a vein)
• Each treatment lasts about 30 minutes
• Treatments are administered in the hospital by a board-certified oncologist
• Dogs receive diphenhydramine (Benadryl) by injection beforehand to reduce the risk of infusion-related reactions

Treatment Schedule

• In clinical studies, treatments were given every two weeks
• Up to 10 treatments may be recommended
• Additional treatments may be considered depending on how the tumor responds

Response Timeline

• It may take one to two months before improvement is seen
• In some dogs, tumors may temporarily appear larger early in treatment—this can occur as immune cells move into the tumor and does not necessarily indicate disease progression

Possible Side Effects

Most dogs tolerate Gilvetmab® well, though side effects can occur. These may include:

• Lethargy
• Decreased appetite
• Vomiting or diarrhea
• Redness of the skin
• Mild swelling of the face, eyes, or ears

If your pet experiences any concerning symptoms, they should be evaluated promptly by Boundary Bay Veterinary Specialty Hospital or a veterinary emergency facility.

Keeping Quality of Life at the Center

Cancer treatment is not just about controlling disease—it is about supporting comfort, function, and meaningful time with family. One of the most promising aspects of monoclonal antibody therapies like Gilvetmab® is their potential to extend survival without sacrificing quality of life.

While no treatment is right for every dog, Gilvetmab® expands our ability to personalize cancer care based on tumor type, stage, overall health, and family goals.

Moving Forward Together

At BBVSH in Bellingham, cancer care is a shared journey. Our board-certified oncologists remain committed to medical rigor, compassionate guidance, and thoughtful integration of advancing therapies like Gilvetmab®—always with your dog’s well-being at the forefront.

If your pet has been diagnosed with a mast cell tumor or melanoma and you would like to explore whether Gilvetmab® may be appropriate, our oncology team is here to help you navigate the options with clarity and care.

Frequently Asked Questions About Gilvetmab® for Dogs

What is Gilvetmab® for dogs?

Gilvetmab® is an immunotherapy medication used to treat certain types of cancer in dogs, specifically mast cell tumors and melanoma. It is the first immune checkpoint inhibitor developed and labeled for use in canine cancer patients.

What types of cancer does Gilvetmab® treat?

Gilvetmab® is labeled for:

• Stage I, II, and III mast cell tumors
• Stage II and III melanoma

Your dog’s oncologist will determine whether this treatment is appropriate based on tumor type, stage, and overall health.

How does Gilvetmab® work?

Gilvetmab® helps the immune system recognize and fight cancer. Some cancer cells can block immune responses by sending “stop” signals to immune cells. Gilvetmab® blocks this signal, allowing immune cells—especially T cells—to recognize and attack cancer cells more effectively.

Is Gilvetmab® chemotherapy?

No. Gilvetmab® is not chemotherapy. It is a form of immunotherapy, meaning it works by supporting your dog’s immune system rather than directly killing rapidly dividing cells. Because of this, it has a different side effect profile than traditional chemotherapy drugs.

Why has BBVSH chosen to offer Gilvetmab®?

The board-certified veterinary oncologists at Boundary Bay Veterinary Specialty Hospital carefully evaluate new therapies before offering them. Gilvetmab® was added because of its targeted mechanism, encouraging tolerance in studies, and potential to improve both quality of life and cancer control in appropriately selected dogs.

How is Gilvetmab® given?

Gilvetmab® is administered:

• Intravenously (IV) in the veterinary clinic
• Over approximately 30 minutes
• With diphenhydramine (Benadryl) given beforehand to reduce the risk of infusion reactions

Treatments are overseen by a board-certified veterinary oncologist.

How often does my dog receive Gilvetmab®?

In clinical studies, Gilvetmab® was given every two weeks, for up to 10 treatments. Some dogs may benefit from additional treatments depending on how their cancer responds.

How long does it take for Gilvetmab® to work?

Gilvetmab® may take one to two months to show visible results. In some cases, tumors may temporarily appear larger early in treatment as immune cells enter the tumor. This does not necessarily mean the cancer is worsening.

What are the side effects of Gilvetmab® in dogs?

Most dogs tolerate Gilvetmab® well. Possible side effects include:

• Lethargy
• Decreased appetite
• Vomiting or diarrhea
• Redness of the skin
• Mild swelling of the face, eyes, or ears

If your dog experiences side effects, they should be evaluated promptly by BBVSH or an emergency veterinary hospital.

Is Gilvetmab® safe for pet owners at home?

Yes. Unlike many chemotherapy medications, no special handling precautions are required at home, making it safer and easier for families.

Is Gilvetmab® FDA approved?

Gilvetmab® has a conditional product license, meaning it has demonstrated a reasonable expectation of efficacy and a preliminary safety profile, while additional long-term data is still being collected.

Can Gilvetmab® be combined with other cancer treatments?

In some cases, Gilvetmab® may be used alongside surgery, radiation therapy, or other treatments. Your veterinary oncologist will design a personalized treatment plan based on your dog’s specific diagnosis and needs.

Will Gilvetmab® cure my dog’s cancer?

While no cancer treatment can guarantee a cure, Gilvetmab® may help reduce tumor burden, slow disease progression, and improve quality of life. Treatment goals are always discussed in detail with your oncology team.

How do I know if Gilvetmab® is right for my dog?

The best way to determine whether Gilvetmab® is appropriate is through a consultation with a board-certified veterinary oncologist at Boundary Bay Veterinary Specialty Hospital. Your dog’s diagnosis, cancer stage, overall health, and family goals will all be considered.

If your pet is experiencing any side effects your pet should be seen by Boundary Bay Veterinary Specialty Hospital or a veterinary emergency room ASAP.