Cancer in Dogs: A Practical Guide for Owners
Cancer is the leading natural cause of death in dogs over 10 years old, affecting roughly half of all older dogs. That statistic is frightening — but it comes with an important counterbalance: veterinary oncology has advanced enormously, and many canine cancers are treatable, some highly so. The trajectory from diagnosis depends enormously on the type of cancer, the stage, and how quickly it's caught.
Most Common Types
- Mast cell tumour (MCT): the most common skin tumour. Can look like an innocent bump. Graded 1–3 based on malignancy — low-grade MCTs are often cured by surgery alone.
- Lymphoma: classic presentation: multiple swollen lymph nodes + lethargy. One of the most responsive canine cancers to chemotherapy. Golden Retrievers have elevated risk.
- Haemangiosarcoma: aggressive vascular tumour — spleen, heart, skin. Often diagnosed at rupture, with acute collapse. German Shepherds and Golden Retrievers at higher risk.
- Osteosarcoma: bone cancer. Predominately large and giant breeds (Irish Wolfhound, Great Dane, Rottweiler). Limping and bone pain are hallmark signs.
- Mammary tumours: common in intact females. ~50 % malignant. Early spaying substantially reduces risk.
- Transitional cell carcinoma: bladder cancer, particularly in Scottish Terriers.
Warning Signs
- New or growing lump anywhere on or under the skin
- Wounds that won't heal
- Unexplained weight loss
- Persistent lameness or bone pain
- Bleeding from body orifices (urine, stool, mouth, nose)
- Difficulty breathing or chronic cough
- Swollen lymph nodes
- Difficulty eating or swallowing
Diagnosis and Staging
FNA for initial assessment; biopsy for definitive diagnosis and grade. Staging (to assess spread): chest X-rays, abdominal ultrasound, CT scan, blood work. Staging guides treatment planning and prognosis.
Treatment Options
- Surgery: gold standard for localised tumours. Clean margins are critical — second surgery to achieve them is almost always worth it.
- Chemotherapy: far less debilitating than in humans. Most dogs don't lose their coat, rarely vomit with modern antiemetic protocols. Quality of life during chemo is usually maintained.
- Radiation therapy: for incompletely resected tumours or sites where surgery isn't possible
- Palliative care: when cure isn't achievable, the focus shifts to pain management and quality of life — dogs respond well to this approach
Log all diagnoses, treatments, and responses in Purzi. Oncologists work with timelines spanning months — having accurate records of when symptoms started, what was tried, and how your dog responded at each step is more valuable than any recollection.