- July
Posted By : PawBoost
Common Signs of Cancer in Dogs

Common Signs of Cancer in Dogs

This article is contributed by guest writer Jennifer Sy (Freelance Journalist).

Dogs make amazing pets; always willing to give us plenty of affection and support. They’re also incredibly resilient, so it isn’t always easy to spot the signs of ill-health.  As a dog owner, it’s important to understand the signs of cancer in dogs so that, in the unfortunate event that they develop the disease, you can get a diagnosis and treatment underway as soon as possible. 

Here are some of the most common signs of cancer in dogs:

Photo Credit: Manuel Meza via Unsplash


Lethargy is one of the most common signs of cancer in dogs. If your dog begins to seem tired all the time and uncharacteristically lacks the energy to play or go for walks, it may be a sign that something is wrong. Cancer can zap a dog’s energy and a steady or sudden decline in their energy levels should prompt you to make a priority vet check appointment.

Loss of appetite or weight

While it can be caused by a variety of things, loss of appetite or weight loss is another key sign of cancer. So, if your dog suddenly stops eating or starts losing weight for no apparent reason, it is important to get them tested by a veterinarian. Other possible signs of cancer in dogs include lethargy, difficulty breathing, and swelling within the abdomen. If you notice any of those signs, don’t hesitate to contact your vet and get them seen as soon as possible.

Photo Credit: Alicia Gauthier via Unsplash

Bumps underneath your dog’s skin

If you notice any bumps underneath your dog’s skin, it is important to have them assessed by a vet. These bumps may well be benign (non-cancerous), or they may be malignant (cancerous). Cancerous tumors can spread to other body parts and cause serious health problems, so it is vital to catch them early. Your veterinarian can determine whether the bumps are cancerous and recommend the simplest course of treatment.

Unusual bleeding, discharge, or toilet habit changes

Another potential sign of cancer in dogs is unusual bleeding, discharge, or any changes in toilet habits. If your dog suddenly starts urinating or defecating more frequently, or if there’s blood in their urine or stool, it is vital that they see a vet urgently. The bleeding may be stemming from an internal bleed relating to a tumor, so any signs like this must be investigated quickly. 

Photo Credit: Ryan Stone via Unsplash

Abnormal odors

Abnormal odors from the mouth, ears or other parts of your dog’s body can indicate the presence of cancer. If you notice an unusual smell coming from your dog, it is important to have it further investigated. Cancerous tumors can release foul-smelling substances that can appear via their breath, within their urine or their stool.

Persistent coughing or vomiting

Cancer can cause various symptoms in dogs, one of which is persistent coughing or vomiting. If your dog is coughing or vomiting persistently, see your vet urgently. Cancerous tumors can cause irritation and inflammation within the tract, which can cause coughing and vomiting. Early detection and treatment are vital for the best possible outcome, so don’t delay in getting them seen by your local vet.

Behavioral changes

Cancer can cause dogs to experience a variety of behavioral changes, such as aggression, excessive whining, or hiding. If your dog suddenly starts exhibiting any of those behaviors, consult with your vet. Cancerous tumors can cause a considerable amount of pain and discomfort, which can result in aggressive behavior. Excessive whining could also indicate that your dog is in pain, and hiding can suggest that they’re feeling vulnerable and afraid.

Photo Credit: Mikhail Nilov via Pexels

Treatments of cancer in dogs

Treatments of cancer in dogs and cats were once largely palliative in nature and focused on relieving the symptoms of the disease. Many of these palliative treatment methods are still widely used today, but there has been a shift towards more curative approaches.

As our understanding of cancer has developed, veterinarian researchers have been able to develop more and more curative methods of treatment. The three most common curative treatments for cancer in animals are surgery, chemotherapy, and actinotherapy.


Surgery is often the primary line of treatment for cancer in dogs. Surgery aims to remove the tumor entirely, as well some surrounding healthy tissues to further reduce the likelihood of the cancer returning. Surgery is also often carried out in conjunction with other therapies, like actinotherapy or chemotherapy for a holistic approach. Your vet may recommend using a protective cone to keep your dog from scratching the wound.

Radiation therapy

Radiation therapy uses high-energy beams, like X-rays or particles, to kill cancer cells. Radiotherapy is also often used both as a primary treatment or together with other treatments, such as surgery or chemotherapy.


Chemotherapy uses drugs to kill cancer cells. Chemotherapy is also a stand-alone treatment as well as a treatment used in conjunction with other treatments, like surgery or irradiation.


Many of the signs and symptoms of cancer in dogs are also signs of far less severe conditions, but it is essential to rule it out first and foremost. With early detection and treatment, many dogs can go on to live happy and healthy lives. If you notice any of the potential signs of cancer listed above, or any changes that seem unusual, don’t hesitate to contact your veterinarian. Early detection and treatment are vital for the best possible outcome.


  • My mollie had little bumps my vet said her breed at this age these bumps were common. Nothing about cancer. They were removed. A few came back a year or so later. Then out of nowhere she was real sick she was still eating but like no energy next day hiding. Rushed to hospital. She was bleeding to death and almost gone. I couldn’t save her. I couldn’t believe it. She was my life! Only 9yrs old. Cocker spaniel. They think it was cancer. I had no idea. Please be mindful of all these signs 🐾🐾🐾💔

  • So very very sorry for the loss. Of your beloved dog.I I understand because it happened to me. I understand that pain!

Leave a Reply