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Understanding Cancer in Dogs

Updated: May 22

Man hugging his senior golden retriever dog.

Cancer in dogs is a topic that touches the hearts of pet owners everywhere, especially as our canine companions age. Just like humans, dogs are susceptible to various forms of cancer, with the most common types affecting the skin, digestive system, and mammary glands (breast tissue) in female dogs. This comprehensive guide aims to shed light on dog cancer, including its symptoms, causes, and treatment options, helping pet owners navigate this challenging journey with informed compassion.


Cancer in Dogs

When we talk about dog cancer, we're referring to malignant tumours—uncontrolled growths of cells that can cause disease by forming lumps and disrupting the normal function of the body's organs. However, it's crucial to understand that not all tumours are cancerous. Benign tumours, which do not spread to other parts of the body, are not classified as cancer. Malignant tumours, on the other hand, can spread and are considered cancerous.

Causes of Cancer in Dogs: Is Prevention Possible?

The exact causes of cancer in dogs can be complex and multifaceted. While certain breeds may be predisposed to specific types of cancer, and factors like spaying a female dog before two years of age can reduce the risk of mammary  (breast tumours), the links between diet, lifestyle, and cancer in dogs are still under investigation. It's important for pet owners to understand that sometimes, despite our best efforts, cancer can still occur.

Recognising Dog Cancer Symptoms

Cancer can affect any part of a dog's body, leading to a wide range of symptoms. However, many cancer symptoms are also common to other diseases, so a professional diagnosis is essential. Pet owners should be vigilant for signs such as:

  • Unexplained lumps or growths on the skin

  • Sores that do not heal

  • Sudden weight loss or loss of appetite

  • Lethargy or weakness

  • Difficulty breathing or limping

  • Persistent digestive or abdominal issues

If you notice any of these dog cancer symptoms, it's crucial to consult with a veterinarian as soon as possible.

Diagnosing and Staging Dog Cancer

Diagnosing cancer in dogs typically requires more than a physical examination. Veterinarians may recommend blood tests, X-rays, ultrasound, MRI scans, or biopsies to determine the presence and type of cancer. These diagnostic tools can also help in "staging" the cancer, which involves assessing whether it has spread to other parts of the body and evaluating the dog's overall health to determine the best course of treatment.

Dog Cancer Treatment Options

Treatment for dog cancer varies depending on the type of tumour, its location, and whether it has spread. The main forms of treatment include surgery, chemotherapy, and radiotherapy, with new therapies such as photodynamic therapy and immunotherapy emerging as potential options. The goal of treatment is often to improve quality of life, slow the progression of cancer, and alleviate symptoms rather than to cure the disease outright.


Surgery is commonly used for isolated lumps that have not spread and can sometimes offer a cure. However, the feasibility of surgery depends on the tumour's location and whether it can be completely removed.


Veterinary chemotherapy aims to slow cancer's progression with minimal side effects, thanks to lower doses compared to human chemotherapy. It's often used when surgery isn't possible or to attempt to prevent recurrence.


Available only at specialist centres, radiotherapy can help manage cancer, though it typically requires multiple sessions under general anaesthesia.

Is Treatment the Right Choice?

Deciding whether to treat a dog with cancer involves considering the animal's quality of life, potential side effects of treatment, and the prognosis. Vets are committed to ensuring that pets remain pain-free, and modern pain management techniques are highly effective. Euthanasia may be considered when a pet's quality of life significantly declines, despite treatment efforts.

Prognosis: How Long Can a Dog with Cancer Live?

The prognosis for a dog with cancer varies widely based on the type of cancer, its stage at diagnosis, and the chosen treatment plan. While some dogs may live comfortably for years with proper management, others may experience a more rapid decline in health.

Facing a diagnosis of dog cancer can be daunting, but understanding the disease, its symptoms, and treatment options can empower pet owners to make informed decisions for their beloved companions. By working closely with a veterinarian, you can navigate the challenges of dog cancer with compassion and care, ensuring the best possible quality of life for your pet.

For further information, read our page on how to know it's time to say goodbye.

If you think your senior dog is struggling and want to book a palliative care appointment or an in-home euthanasia appointment, contact our team on 0800 049 5944 or


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