The environmental footprint of pet diets

Food production is one of the factors that influence environmental impact, and therefore, its importance regarding sustainability should not be overlooked.

As the pet population increases, more pet food is consumed around the globe. Pet food is a relevant topic when considering environmental impact because of the type of ingredients used: by-products and animal products are present in moderate to high amounts, and these ingredients are perceived as having a high environmental impact.

The research

Our study was conducted at the Pet Nutrology Research Center at the University of São Paulo, and it was recently published in Nature’s journal Scientific Reports. The study aimed to evaluate the impact of Brazilian dry, wet and homemade diets for adult dogs and cats on some environmental impact parameters, such as greenhouse gas emission and land use.

A total of 938 diets for healthy adult pets were evaluated – 618 for dogs and 320 for cats. Most of the diets had more protein and fat of animal origin than of vegetable origin, and many of the ingredients on the labels were from animal sources.

According to the results, wet diets were responsible for the highest environmental impact for all variables evaluated, and dry diets were the type of diet that least impacted the environment. Homemade diets had an intermediate environmental impact for most variables evaluated, and some variables such as water use were similar to those seen with dry diets.

More energy, more impact

Another analysis in the study showed that diets containing higher energy content from animal sources had a higher environmental impact. The main reason we believe wet diets had a higher environmental impact, is that most of them have higher amounts of animal protein, such as some by-products or even fresh meat, than dry or homemade diets.

As previously reported in other studies, animal protein sources are thought to have a higher environmental impact than other sources of protein or other types of ingredients, and because they are present in moderate to high amounts in pet food, the impact of these diets on the environment can be significant.

The results suggest that, depending on the type of diet consumed, a dog with an average body weight of 10 kg would be responsible for 12.4% to 97.8% of the annual emission of a Brazilian citizen. If we consider the impact of the dog population in Brazil, this could represent 2.9% to 24.6% of the total estimated emission of CO2 equivalents for Brazil in a year – which is significant and should not be overlooked.

These are only estimations

It is important to understand that the results of this study are only estimates because we did not have access to the manufacturers’ recipes of the actual diets. A few factors, such as the use of animal by-products instead of fresh cuts of meat, could lower the estimated impact, but unfortunately, we did not have this information at the time of writing the article.

Many factors can influence the sustainability of food, such as ingredients and their inclusion in the diet. Animal protein is perceived as the villain in the discussion of environmental sustainability, but the source is very important.

Animal proteins from areas that have a high rate of deforestation can cause more impact than other proteins from more sustainable sources, such as ones that use intensive farming methods.

That said, dogs and cats are carnivores who require several nutrients that come mainly from animal sources. Therefore, these ingredients should be included in their diets.

Rethinking the formulation?

We believe our results demonstrate the importance of pet food as a part of our impact on the planet. Most diets contain an excess of nutrients, and some advertise a higher protein content than necessary.

Our study suggests that if the industry wants to take a more sustainable approach, it needs to rethink the way it formulates diets and which claims are more sustainable so that we can better address this topic with pet owners.

There is no single strategy for reducing the environmental impact of pet diets, and each manufacturer should review their process and determine what they can do to improve the sustainability of their production system.