Cancer is one of the leading causes of death in dogs, particularly older animals. Approximately 1 in 4 dogs will develop cancer during their lifetime, and in dogs over 10 years of age, cancer accounts for nearly 50% of deaths. Unlike many conditions, cancer diagnosis triggers complex welfare and ethical decisions for owners and veterinarians — balancing treatment efficacy, side effects, quality of life, and the dog's experience of illness and medical interventions.
Pain management is central to welfare-centred cancer care. Cancer pain in dogs arises from:
Assessment tools such as the Glasgow Composite Measure Pain Scale and the Canine Brief Pain Inventory (CBPI) help owners and vets track pain levels over time. Any dog with cancer should have pain regularly assessed and managed proactively.
The Villalobos Quality of Life Scale (HHHHHMM — Hurt, Hunger, Hydration, Hygiene, Happiness, Mobility, More good days than bad) provides a structured framework for ongoing assessment. Key welfare indicators include:
Curative or debulking surgery may offer long-term remission. Welfare considerations include anaesthetic risk, post-operative pain, recovery time, and — in procedures like amputation — adaptation to altered body function. Dogs generally adapt remarkably well to three-legged life.
Veterinary chemotherapy protocols use lower doses than human protocols, aiming for quality of life preservation rather than cure at all costs. Side effects (nausea, lethargy, bone marrow suppression) must be monitored and managed. Most dogs maintain good quality of life during treatment.
Used for local tumour control, particularly for brain, nasal, and oral tumours. Requires anaesthesia for each session. Side effects include radiation dermatitis and mucositis.
When curative treatment is not pursued, palliative care focuses on pain control, comfort, and maximising good days. NSAIDs (meloxicam), opioids, gabapentin, and supportive nutrition form the cornerstone of palliative cancer care.
Cancer often leads owners to face end-of-life decisions. Welfare-centred guidance emphasises that euthanasia before suffering becomes unmanageable is a gift, not a failure. The "more bad days than good" threshold from the HHHHHMM scale provides a practical decision point. Anticipatory discussions with veterinarians help owners feel prepared rather than blindsided.