Parasite control in dogs involves significant welfare trade-offs between protecting individual animals from parasites and avoiding unnecessary chemical treatments with their own health and environmental impacts.
Dog parasite control sits at the intersection of individual welfare, environmental health, and pharmaceutical stewardship. Untreated parasitism causes genuine suffering — flea allergy dermatitis, anaemia in heavy infestations, heartworm disease, and tick-borne illness are all welfare-significant conditions. However, routine, calendar-based treatment of all dogs regardless of exposure risk contributes to unnecessary chemical load in the environment and potentially to resistance development. The current evidence-informed approach is risk-based: assessing each dog's actual exposure risk through lifestyle factors, geographic location, and clinical signs, and tailoring treatment accordingly. This requires informed owner engagement and veterinary guidance rather than simply defaulting to the broadest available prophylactic treatment. Welfare is best served by treating parasitism effectively when present and preventing it efficiently where risk is genuine.