Estimating the environmental impact of dog foods marketed in the UK

Environmental impacts of feeding dogs are substantial and growing due to increasing dog populations and trends towards feeding more meat. Impact estimates vary widely. Animal by-products are carcass portions in low demand for human nutrition but commonly used in pet food. Determining the environmental impacts of producing these byproducts, when compared to prime meat, is challenging and some methodologies overestimate. Using ingredient and nutrient label data, we develop a model to more accurately estimate impacts. We assess 996 dog foods sold by a single retailer in the UK: 526 dry; 114 dry grain-free; 7 dry plant-based; 197 wet; 113 wet grain-free; 5 wet plant-based; 34 raw foods. Our open-source linear programming approach is reproducible, allows comparison of by-product allocation methods, and yields detailed results. The results show emissions intensity varied over 65-fold across products, with prime meat driving higher impacts. Ingredient production for UK commercial dog foods contributes 2.3–3.7 % of UK food system GHG emissions, or 0.9–1.3 % of total UK emissions. Extrapolating from UK results, to meet global dog population feed needs for commercial food we estimate emissions of 469–792 Mt CO₂-eq for ingredient production – 59–99 % of jet-fuel emissions from commercial aviation. Population level feeding trends toward wet, raw, and grain-free formats increase impacts, while plant-based foods are likely to reduce them. More attention needs to be paid to the environmental impacts of feeding pets, including improved understanding of the ingredients supply chain and how moves to less impactful diets can be supported.