Prevalence
Most common cancer in intact female dogs. Risk drops to ~0.5% with spay before first heat, ~8% after first heat, ~26% after second heat. Roughly half are malignant.
Who gets it
Intact or late-spayed female dogs, median age 10 years. Poodles, Spaniels, Dachshunds over-represented.
Symptoms to watch for
- One or more masses in the mammary chain
- Sometimes ulceration or bleeding
- Diffuse swelling/redness (inflammatory mammary carcinoma — emergency)
- Regional lymph node enlargement
How it's diagnosed
- Excisional biopsy of all masses, with histopathology
- Three-view chest radiographs for pulmonary staging
- Abdominal ultrasound
- Lymph node aspirate
- ER/PR receptor status — emerging area
Prognosis ranges
Benign: surgery curative. Carcinoma <3 cm with clean margins: median >2 years. Carcinoma >5 cm: median 6 months. Inflammatory mammary carcinoma: median <2 months — palliative care often the kindest path.
Treatment landscape
Recurrent mutations in this cancer
Frequencies from canine clinico-genomic cohorts. SciRouter Oncology auto-checks every mutation in your dog's report against the OncoKB-aligned database for matched targeted therapies.
Questions to ask your vet
- Are these benign or malignant? What histologic types?
- What's the grade and margin status?
- Should we spay her at the same time?
- Are there pulmonary metastases?
- Is this inflammatory mammary carcinoma? (If yes, we need a very different conversation.)
- Is there value in adjuvant chemo for this stage?
Quality-of-life notes
Most dogs recover very well from mastectomy. Inflammatory mammary carcinoma is the exception — it's a true emergency with poor prognosis, and palliative care should be considered alongside any treatment discussion.