Everybody already knows the answer. That’s the problem.
Ask any cat person or dog person whether their animal makes their life better and you will get a yes so immediate it barely qualifies as a response. Which is exactly why the research question is hard. When a conclusion is this universally believed, it is very easy to design a study that finds it, and very tempting not to notice you did.
Mars, Incorporated is now running the largest research program ever attempted on this question. It’s called PAWS, the Pets and Wellbeing Study Program, it’s led by the company’s Waltham Petcare Science Institute, and it is genuinely enormous: more than 35,000 people across upwards of 20 countries in the first phase alone, with more studies planned on top.
Mars is also the largest pet care company on earth. It sells the food, it owns the veterinary clinics, and it has a direct commercial interest in the finding that pets are good for you.
That is not a reason to dismiss PAWS. It is the reason to pay attention to how it’s built.
Why anybody is spending this much money on this
The framing that makes PAWS make sense is not “are pets nice.” It’s that mental health has become the health problem people are most worried about, and the field is short on interventions that are cheap, scalable, and not a pill.
The scale of the worry is documented. Ipsos, in its Health Service Report, surveyed 31 countries and found that mental health was the health issue people ranked first, at 45 percent, a share that has been climbing since 2018. It now sits above cancer, above drug abuse, and above coronavirus in how much people say they worry about it. That ranking explains why an intervention as ordinary as “a household already contains a dog” is suddenly interesting to serious researchers.
The existing evidence is real but thin in a specific way. Plenty of studies have found positive associations between pet ownership and mental and physical health. Very few have been big enough, long enough, or careful enough to say how the effect works, who it works for, or whether it works at all for people whose circumstances make pet care a burden rather than a comfort. That’s the gap PAWS says it’s aiming at.
What they’re actually going to study
The program is deliberately broad rather than deep on any single question, which is both its strength and the thing that will make it hard to interpret.
The stated targets are stress, loneliness, anxiety, and sleep. Individual studies within the program include an evaluation of what pet interaction does for older adults, an assessment of how the wellbeing of dogs themselves changes after they’re adopted (a nice inversion, since the animals in this literature are usually treated as the treatment rather than the subject), and a global look at what pet parenting does to human sleep.
The academic partners are not decorative. They include the Cummings School of Veterinary Medicine at Tufts, the University of Pennsylvania School of Veterinary Medicine, the University of Liverpool, the polling firm YouGov, and the Human Animal Bond Research Institute. Dr. Maggie O’Haire, Associate Dean for Research at the University of Arizona College of Veterinary Medicine, is among the researchers involved, and she is one of the more rigorous people working in this area.
Loïc Moutault, president of Mars Petcare, has framed the program publicly around a familiar personal observation: that pet owners feel the benefit firsthand, and the evidence increasingly supports what they feel. Which is a perfectly reasonable thing for him to say and also, precisely, the assumption a study is supposed to test rather than start from.
The funding question, stated plainly
Industry funding does not make research false. It does make it predictable, and there is a large literature on exactly how.
In nutrition science, in pharmaceuticals, and in tobacco, industry-sponsored studies have been shown to reach conclusions favorable to the sponsor more often than independently funded studies on the same questions. The mechanism is rarely fraud. It’s a hundred small, defensible decisions: which questions get asked, which comparison group gets used, which outcome gets designated the primary one, which findings get written up quickly and which sit in a drawer.
So the useful question about PAWS is not “can we trust Mars.” It’s whether the program is designed in a way that would let it find a negative result and report it.
There are three things worth watching for.
Preregistration. Are the hypotheses, the primary outcomes, and the analysis plans registered publicly before the data comes in? That single practice is the most effective known defense against a study quietly reshaping itself around whatever it happened to find.
Independence of the analysis. Are the academic partners running the numbers, or are they lending their names to numbers run in-house? The list of institutions is impressive. Their actual authority over the results is the thing that matters.
Publication of nulls. The tell will come in a few years. If PAWS publishes a study finding that, say, pet ownership does nothing measurable for loneliness in a given population, or that it worsens sleep, then the program is doing science. If every output confirms the premise, it’s marketing with a very large sample size.
“The honest version of this research will find that pets help some people enormously, do very little for others, and make life harder for a few,” says Dr. Priya Nair. “I’d take that paper seriously. What I’d trust least is a result that says everyone benefits equally, because that’s not how any intervention works, including the ones that clearly do work.”
What a good answer would actually look like
If PAWS works, the payoff is not another headline saying pets are good for you. It’s specificity, and specificity is what would let this research change anything.
Which people benefit most: the isolated, the newly bereaved, the chronically ill, or the already-well? Does a cat do something different from a dog, and for whom? Does the benefit come from the animal, or from the walk, the routine, the reason to leave the house, and the neighbors you’re forced to talk to? That last question is the sharpest one in the field, because if the mechanism is routine and social contact rather than the animal itself, then the intervention is not “get a pet,” and a pet-food company might be the last organization inclined to say so.
And the ugly question, the one PAWS is uniquely positioned to ask honestly and uniquely disinclined to: for whom is a pet a net harm? For someone in poverty facing a $4,000 vet bill, someone whose disability makes daily care a strain, someone whose housing is unstable, the animal can be a source of significant distress. A study program this large could actually measure that, and the finding would matter more than another confirmation of what everyone already believes.
What’s new since this was written
PAWS is now running, with its own public hub at mars-petsandwellbeing.com, and the program has kept expanding since the announcement.
The most interesting addition is a study called “Cats and the Good Life,” which sets out to examine the benefits and drawbacks of living with a cat, explicitly compared against the previous findings on dogs. Two things about that are encouraging. Cats are chronically under-researched relative to dogs in this literature, largely because they are harder to study and less cooperative about it. And the word “drawbacks,” sitting in a study title funded by a company that sells cat food, is a small but real signal that somebody in the design room is thinking about credibility.
That’s what to watch. Not the press releases about how much people love their pets. The papers that admit where the love runs out.
References
- Mars, Incorporated. “Mars launches landmark global study program on pets’ contribution to human wellbeing.” February 2025. Link
- Mars Pets and Wellbeing Study (PAWS). Link
- Ipsos. “Ipsos Health Service Report.” Link
- Human Animal Bond Research Institute. Link
- Lundh, A., Lexchin, J., Mintzes, B., Schroll, J.B., Bero, L. “Industry sponsorship and research outcome.” Cochrane Database of Systematic Reviews, 2017. Link
- Waltham Petcare Science Institute. Link
