Nearly one billion dogs and cats now live in more than half of all global households, their combined biomass outweighing all remaining wild terrestrial mammals. In the U.S., nearly two-thirds of homes include at least one companion animal.

The pet food industry will expand from $32.2 billion to $44.5 billion by 2027, which this paper states is partly fueled by companion animal guardians demanding premium human-grade formulations that often exceed pets’ actual nutritional requirements. According to the researchers, these protein-dense meals carry ecological consequences that receive insufficient attention.

Canine and feline diets remain conspicuously exempt from the climate scrutiny applied to human food despite relying on the same systems. The paper contends that this sector’s carbon footprint gets downplayed by narratives suggesting it merely “recycles” unwanted animal byproducts.

Thus, the researchers seek to quantify pet food’s environmental costs and explore whether plant-based options could help mitigate the industry’s climate impact.

A literature review was conducted in November 2024, searching multiple databases with the phrase “environmental impacts” AND “pet food.” The researchers retrieved over 3,300 articles, ultimately analyzing 21 studies that met their inclusion criteria for:

• Directly measuring pet food’s environmental impacts
• Comparing meat-based and plant-based options
• Including global, national, or product-specific data
• Being available in English with full text

They focused primarily on dogs and cats, noting that these companion animals represent 95% of global pet food sales. Insect-based pet food studies were omitted entirely, with the authors citing concerns about scalability, unresolved questions regarding insect sentience, and welfare implications of intensive farming practices.

Although the well of research literature on companion animals’ environmental impacts is relatively shallow, the review identifies consistent patterns that illustrate the scale of the issue and debunk myths surrounding animal byproducts.

Ecological Pawprints

Companion animals create environmental pressure through their basic needs and the infrastructure built around their care. Multiple life-cycle assessments reveal that ingredient selection accounts for 70% of pet food’s carbon impact, outweighing effects from processing, packaging, or distribution.

The industry’s footprint is far from neutral, as these figures make clear:

• Globally, dogs and cats consume 9% of farmed animals, and this rises to 20% in the United States
• Dry food accounts for 25 to 30% of the environmental impacts of U.S. farmed animal production
• Wet food generates almost eight times more carbon dioxide-equivalent greenhouse gas emissions than kibble
• Large dogs have an ecological footprint nine times greater than small dogs

Pet population alone doesn’t explain these consumption levels. The authors observe how guardians often overfeed their companion animals as an expression of affection, explaining how dogs and cats are increasingly consuming more calories than they need while manufacturers overproduce to meet inflated demand.

Byproduct Myth

Animal byproducts include animal parts such as ears and snouts as well as the components derived from them like fats and bone meal. Together, these materials constitute over half the meat-sourced ingredients in U.S. dog and cat food. Popular belief holds that these materials are “saved” from landfill decomposition for companion animal use in an act of environmental stewardship that offsets our own meat consumption.

The review systematically dismantles this characterization:

• Only 25% of these materials go to companion animal food in wealthy nations like the United States
• Byproducts are commodities that would find buyers in other industries regardless of the pet industry’s demand
• Pharmaceuticals, energy, and other sectors actively compete for these resources, generating 11% of beef revenue and 7.5% of pork revenue
• These materials are nutritionally inefficient, with lower protein density that requires 1.4 times more farmed animal carcasses for dogs and 1.9 times more for cats compared to higher-quality meat cuts

The authors reframe these ingredients as coproducts that augment rather than reduce farmed animal demand. Mislabeling them as “waste” conceals how byproducts fuel additional meat production.

Potential For Alternative Diets

The researchers argue that switching to plant-based alternatives represents the most direct path to carbon reductions. Their modeling suggests that a global transition to vegan companion animal diets could free land equivalent to Mexico and Germany combined while cutting greenhouse gas emissions equal to the U.K. and New Zealand’s annual totals.

Plant-based ingredients already constitute about 47% of commercial formulations with dramatically lower climate impacts. Historically, many have doubted the nutritional adequacy of vegan diets for companion animals — and cats in particular. However, vegan options are outpacing the rest of the market in growth, suggesting more guardians are open to these options. Citing existing research (with measured caution), the authors present that well-formulated products show promise, though they recognize nutritional evidence isn’t as robust as their core climate findings.

Precision fermentation and cultivated meat are also highlighted as emerging alternatives. However, both are in early stages of development with industrial-scale production several years away.

Limitations

Multiple limitations are acknowledged. The authors didn’t conduct a systematic literature review, potentially introducing selection bias. Most research originates from wealthy countries, limiting universal applicability. Environmental impact estimates varied widely between studies. Some found footprints several times larger than others depending on the country, product formulation, and methodology.

One author discloses financial ties to the vegan companion animal food industry, and the research received funding from organizations with clear positions on these issues. Much of the analysis builds on the other author’s earlier work, potentially compounding bias. Many of the referenced studies on vegan pet food rely on observational data rather than controlled trials, with some lacking peer review or independent replication.

These elements don’t necessarily invalidate findings but imply approaching climate and animal health benefit claims with caution.

Conclusions

The researchers emphasize that we have only several years before irreversible ecological tipping points are reached and, therefore, leaving it to consumer choice to resolve a major emissions source becomes morally indefensible. Policy can deliver immediate, large-scale transitions that voluntary adoption can’t match in the time remaining.

To that end, they recommend the following:

• Reclassifying byproducts as coproducts to reflect their true economic value
• Including companion animal food in national emissions inventories and reduction targets
• Mandating carbon labeling comparable to human food requirements
• Funding research and development for alternative proteins in companion animal nutrition
• Creating transition assistance for manufacturers and retailers

Their vision holds that meaningful climate progress may depend partly on extending environmental thinking to previously overlooked areas of consumption, including how we feed not just ourselves, but the companion animals we love.