Behind the substantial but uncertain environmental impacts of pet foods

Producing pet food has environmental consequences, but the exact role is currently largely absent from the wider environmental sustainability discourse or research. What research has been conducted shows substantial disagreement, both due to a lack of publicly available data on what is in the foods and the choices about how to account for the use of by-products in pet foods. However, trends in the pet food market, and global rises in pet ownership, suggest more clarity is urgently needed.

Premium, sustainable – or both?

There are 2 trends in the pet food market that suggest contradictory outcomes on resources used in pet food production. Firstly, a major trend is toward premiumization or humanization of pet foods, which is particularly strong in North America, Western Europe and Australasian markets. These foods, particularly where they contain more meat, will increase the resources used to produce them. A second trend is a growing interest in sustainable pet foods, with multiple new brands launched in this space.

More sustainable pet foods, just as in human nutrition, will use commodities that have lower footprints. This includes a reduction in meat (especially ruminant meat), with increased quantities of plant-based ingredients. Obviously, appropriate and balanced animal nutrition needs to be maintained even with vegan foods. The use of by-products is highly relevant for pet foods, where using the by-products that lack other alternative uses, and therefore have the lowest values, would be preferred. Novel ingredients, such as insects, could also play a role. However, the question then becomes how and on what were the insects themselves fed.

A circular economy view that considers the system and alternatives is therefore needed to understand the impacts of such approaches.

Here again, if very low-value waste or by-product streams could be used to grow insects, then low-impact food could be produced.

The role of by-products

Animal by-products (ABP) are a traditional way to provide suitable pet nutrition at a low cost. The most common ingredients found in commercial dry and wet diets are poultry ABPs, with an average of 32% of dry pet food in the US market being ABP.

When attempting to allocate environmental harms, a critical decision is how to account for these by-products. Previous studies assigned an environmental impact factor that treats ABPs as if they were human-grade meat. The life-cycle assessments used to derive these environmental impact factors are targeted at the functional unit of meat production and so they should not be directly used for ABP.

An alternative approach would be to ascribe zero impact or emissions to ABPs. This approach would be the opposite extreme of taking meat-related emissions and would reduce the impact of pet food consumption. However, ABPs are not valueless, so they provide a financial return to the livestock industry that incentivizes increased livestock production, and should therefore be associated with some level of emission.

A third allocation option to deal with emissions from ABP is using the relative economic value of the different products, which falls between the 2 extremes of a meat impact factor and no impact.

The lower price of the ABP relative to meat implies emission associated with it would also be considered to be lower. For example, bovine ABP per kg is just 8% of the beef emission using an economic value allocation. Using this approach, we showed in a published study emissions of 0.87-1.94 CO2eq/1,000 kcal across the range of dry dog foods with a US market consumption average of 1.24 CO2eq/1,000 kcal. This would be approximately 3.4 times lower than shown in previous studies for dry food, and 27 times less than for wet foods.

Demand is at an all-time high

Global pet ownership is increasing, with current estimates of over 840 million cats and dogs worldwide in 2023, according to Statista. There has been a dramatic rise in many regions, including China and the United States. In the US, pet ownership has increased from 56% of households in 1988 to 66% in 2023, according to Forbes, with $58.1 billion (€52.4B) spent on pet foods. Feeding this increasing population of pets implies an increasing environmental burden from producing the food they consume.

The environmental paw print from pet foods could be reduced by either lowering the demand or by using food that can be produced more sustainably.
If reducing the number of pets is considered too controversial or otherwise unacceptable, then demands for pet food can still be reduced by having the same number of smaller animals. Trading down from a Great Dane to a Chihuahua would still provide some of the benefits of dog ownership, but place less pressure on the environment to maintain the dog.

The numbers

The environmental impact of currently consumed pet food is still unclear and contested. A recent study explored the environmental impact of dog and cat feed, showing greenhouse gas emission rates of 33.56 kg CO2eq/1,000 kcal for wet food and 4.25 kg CO2eq/1,000 kcal for dry pet food. Further research has suggested that US dry cat and dog food emissions were 25-30% of emissions associated with providing food to US citizens. While these results are shocking, they rely on choices about how by-products are accounted for that are hard to justify.

The environmental impact of pet foods should not be ignored, but further research that makes appropriate consideration of by-product emissions – rather than applying emission factors from meats – is needed. Increases in pet ownership and changes in pet food markets make such understanding and debate even more critical.