Educating yourself about the warning signs a dog has cancer—and checking for signs regularly—might prolong your beloved pet’s life. We don’t like to think about the end of our pets’ lives, especially when they seem healthy. But devastating statistics show that cancer is the leading cause of death in adult dogs and cats.

There are many types of cancer in dogs. The median age to receive a dog cancer diagnosis is between eight and nine years. And even if your dog never has a diagnosis, 50% of all dogs who live to age 10 will eventually succumb to the disease.

The good news is that many cancers can be treated. We just have to be willing to act upon the warning signs.

Common Types of Cancer in Dogs

Mast Cell Tumors in Dogs

Mast cell tumors in dogs usually show up as a skin mass, but they can vary widely in their appearance. Tumors might be on or beneath the skin. They can appear smooth and pink or raw and ulcerated. Mast cell tumors can change size, so a lump or bump that seems to get bigger and smaller from day to day could be one of the signs a dog has cancer.

What to Expect When Your Dog Has a Mast Cell Tumor
In general, mast cell tumors in dogs respond well to treatment, although outcomes depend on the tumor size, location, and grade. Any new lumps or bumps should be examined by a veterinarian as soon as possible.

Tumors that are easily felt and differentiated in the skin are more likely to be successfully removed with surgery. The higher the grade of the tumor, the more aggressive it can be.

Chemotherapy and radiation can significantly improve outcomes—but dogs that develop one mast cell tumor have a higher likelihood of developing others in their lifetime, so continued testing is important, even after a successful mast cell tumor removal.

Lymphoma in Dogs

Lymphoma in dogs often shows up as multiple enlarged lymph nodes on the outside of the body. But it is considered a whole-body type of cancer, so it often affects multiple locations: external and internal lymph nodes, the skin, mouth and lungs, and organs such as the liver and spleen.  

What to Expect When Your Dog Has Lymphoma
The most common test for diagnosing lymphoma in dogs is Fine Needle Aspiration (FNA). Your pet’s veterinarian will take aspirates of the lymph nodes, which can help to make the diagnosis and determine treatment options.

Lymphoma in dogs has very high response rates to chemotherapy, which can prolong life for as long as a year in some cases. However, once diagnosed, most dogs will have a relapse of lymphoma at some point and, over time, chemotherapy becomes less effective.

Osteosarcoma in Dogs

While osteosarcoma in dogs may appear as a localized tumor in the bone, it has a high likelihood of spreading (metastasizing) to other organs, such as the lungs.

What to Expect When Your Dog Has Osteosarcoma
By the time they are diagnosed, approximately 90%–95% of dogs with osteosarcoma will already have the disease throughout their bodies. These tumors may be microscopic, meaning you won’t be able to see or feel them.

When osteosarcoma in dogs affects the legs, amputation is considered the best treatment for pain relief and to avoid fracture of the affected limb. Although osteosarcoma is considered a highly metastatic cancer, chemotherapy can be very effective in preventing cancer spread for up to a year, and possibly longer.  

Signs of Cancer in Dogs

The first thing to do if you notice one of the warning signs a dog has cancer is to track symptoms through photos and notes. The more information you have, the better. Signs of cancer in dogs to watch out for include:

Lumps, bumps, skin lesions, and wounds that won’t heal

• Mast cell tumors in dogs can look and feel similar to benign tumors. The only way to know for sure if a tumor is cancerous is to get a sample.
• Lymphoma in dogs can appear as lumps and/or enlarged lymph nodes.

Difficulty moving, “lameness”

• Osteosarcoma in dogs most often shows up as lameness that may occur after a lot of activity or might come on slowly.

Enlarged lymph nodes

• Enlarged lymph nodes are often one of the first signs of lymphoma in dogs.

Unexplained weight changes

• Changes in eating and drinking habits, as well as gaining or losing weight rapidly can be one of the signs of cancer in dogs.

Gastrointestinal signs

• Bad breath
• Vomiting
• Bloating
• Diarrhea
• Difficulty passing food

Abnormal bleeding

• Abnormal bleeding, including blood in urine or feces, should be checked out by your family veterinarian.

Tests for Cancer in Dogs

Early detection is crucial for best outcomes after a dog cancer diagnosis. And tests for cancer in dogs have become quite advanced. The first thing a veterinarian will do is examine your dog’s medical history. Make sure to bring any photos and notes you have taken about specific symptoms.

The veterinarian will do a thorough physical exam as well as blood, urine, and other tests for cancer in dogs, including assessing the lymph nodes to determine if the cancer has spread to other parts of the body.

Depending on what is found, follow-up tests may include:

• Excisional biopsy (removing cells or tissues for biopsy)
• Imaging (ultrasound, radiographs, CT, MRI scans)
• Fine-Needle Aspirate (FNA), which involves using a needle and syringe to suction cells from a tumor or the lymph nodes in order to examine them under a microscope.

What to Expect After a Dog Cancer Diagnosis

With any cancer, early detection and assessment are key to longer survival rates. The outcomes after a dog cancer diagnosis depends on many factors, such as:

• The dog’s age and overall health, including any pre-existing conditions
• The type and stage of cancer
• The location and size of the tumor

It’s never too early to educate yourself on the warning signs of cancer and what to do after a dog cancer diagnosis. Your family veterinarian and veterinary oncology teams are there to help guide you through the process.

Compassionate Care for Your Dog—And You!

Finding out that your furry family member has cancer can be scary and painful. At Veterinary Specialists of the Rockies, we care deeply for our own pets, so we understand what you’re going through. It’s not just a job to us. That’s why we work with your primary care veterinarian to provide compassionate veterinary oncology before and after a confirmed cancer diagnosis.

Above all, we can provide detailed, personalized information all along the way so that you can make the most informed decisions possible. We can help equip you with the knowledge you need to weigh pros and cons of various treatments, or combinations of treatments, throughout your pet’s health journey.

Cancer Treatment for Dogs

Quality of life is the goal of any cancer treatment for dogs. The aim will always be to limit side effects, pain, and discomfort as much as possible. Technology and oncological research are constantly advancing, which may provide new options for clinical trials and experimental drug therapies in the future.

Your dog’s cancer treatment plan will depend on the circumstances. But, in general, if a cancerous tumor can be entirely removed, surgery is the best choice of treatment.

When cancer has spread throughout the body or surgery couldn’t remove all tumors, it’s common to follow up with radiation therapy and electrochemotherapy, which is a way to localize chemotherapy to more effectively shrink accessible tumors and eliminate microscopic cancer after surgery. 

Cancer treatment for dogs may also include immunotherapy (specialized vaccines, checkpoint inhibitors), which helps train the dog’s immune system to fight the cancer itself.

Other cancer treatments for dogs (and combinations of treatments) are also available, such as bisphosphonate therapy for bone pain and anti-angiogenesis to target blood vessel growth.

Contact Veterinary Specialists of the Rockies

If you see warning signs a dog has cancer, we’re here as a resource for you. You can book an appointment with our oncology team at Veterinary Specialists of the Rockies by calling 303.660.1027 (no referral or pre-existing cancer diagnosis is needed). 

Our board-certified oncology specialists, Dr. Jennifer Arthur and Dr. Erin Arnold, are honored to help you through what can be a very difficult time.

For immediate emergency assistance or to book an appointment, call 303.660.1027.