Cancer in older dogs

Cancer is the leading cause of death in older dogs. In records of 74,556 North American dogs, young dogs died mostly of gastrointestinal and infectious causes, whereas older dogs died of neurologic and neoplastic causes, and larger breeds carried a higher risk of death from cancer at a younger age¹. Many breeds carry particular risks, reviewed in the veterinary literature². The AVMA lists cancer among the conditions that become more common with age and notes that animals often hide illness until it is advanced³.

The signs are the general ones of the senior checklist: a new lump, a lump that grows or changes, weight loss, poorer appetite, tiredness, a wound that does not heal, lameness that does not settle, a swollen belly, or bleeding from anywhere³⁴. None of these means cancer, and all of them deserve a visit.

Any lump should be measured, photographed and dated in Oldie's care history, and a sample taken by the vet, because a needle test is the only way to tell a fatty lump from a mast cell tumour. Early treatment is often less invasive and more successful. When a cancer cannot be cured, comfort-focused care can still give good months.

This is general information, not a diagnosis. Your vet knows your dog.

Sources

1. Mortality in North American dogs from 1984 to 2004: an investigation into age-, size-, and breed-related causes of death (Fleming JM, Creevy KE, Promislow DEL). Journal of Veterinary Internal Medicine 25(2):187-198, 2011 (peer reviewed). Accessed 2026-09-22.
2. Breed-Predispositions to Cancer in Pedigree Dogs (Dobson JM). ISRN Veterinary Science, 2013 (peer reviewed review). Accessed 2026-09-22.
3. Caring for senior cats and dogs. American Veterinary Medical Association. Accessed 2026-09-22.
4. 2023 AAHA Senior Care Guidelines: Evaluating the Unhealthy Senior Pet. American Animal Hospital Association. Accessed 2026-09-22.