Prom Week has arrived in Tennessee, and the class of 2024 is lined up in suits and crowns, posing for pictures by the red carpet. Who says four legs and a tail should stop you from going to the ball?

It’s just another day in doggy daycare. As well as a graduation ceremony, canines at this facility in Franklin, Tennessee, on the outskirts of Nashville, were recently treated to bark-uterie – customized charcuterie boards – and challenged by Sports Week, for which they were dressed up with sweatbands.

“I did have someone tell me that our daycare calendar has more activities than their child’s school,” reflects Samantha Talbot, who manages the site, inside the North American headquarters of Mars Petcare.

There is method – and money – in all this madness. The pet industry is booming. Across the world, the market is projected to swell to almost $500bn by the end of the decade. In the US alone, it is expected to attract more than $150bn in spending this year, up from $97.1bn just five years ago.

Mars is at the center of this surge. While perhaps most associated with its myriad brands aimed at humans, from M&Ms and Wrigley’s gum to Dolmio cooking sauce, the sprawling conglomerate – one of the largest private companies in the world – now generates more money from its animal-focused businesses than those aimed at people.

It is behind dozens of pet food brands, including Royal Canin, Pedigree, Sheba and Whiskas, as well as nearly 3,000 veterinary clinics, hospitals and diagnostic labs. Of the $50bn in sales Mars generated in 2023, the company says about 60% came from its pet-care arm.

But demand is shifting as rapidly as it is growing. A new generation of owners has brought new priorities, concerns and approaches – as demonstrated by the parades at Mars’s US pet HQ.

“Thirty years ago dogs slept in the garden,” Loïc Moutault, global president of Mars Petcare, noted as he toured some of its Tennessee sites with the Guardian. “Now they sleep in our beds!”

More people are getting pets earlier in their lives, he said. An estimated 16% of American pet owners are now gen Z.

Not that Mars calls them owners. “Pet parents” are less likely to ban their animals from certain rooms, as was once the norm, and more likely to take them away on holiday. “The depth of the relationship is completely different,” according to Moutault.

This generation is also far less prepared to trust pet food companies or even vets. Younger owners do their homework – and readily challenge the vets treating their pets, and the companies making their food. “This generation is way more cynical, and therefore demanding,” Moutault said, “in terms of how genuine we are about what we are proposing and offering.”

Mars first branched out into the pet industry when it bought the British maker of Chappie canned dog food in 1935. More recently, the company built up a vast chain of veterinary clinics and hospitals through a multibillion-dollar string of takeovers.

The accelerated growth of its pet-care division has helped Mars double sales across its wider business over the past decade. The man behind its recent expansion in this market, Poul Weihrauch, was promoted to run the whole company in 2022.

Top executives at Mars believe sales in this market will – and should – surge for years to come. “Pets make a better world for us,” says Moutault. “We want to make a better world for pets.”

The conglomerate’s Franklin site is complete with a dog park with wifi, how company brass say every office should look. Mars has so far certified nearly 150 US cities as pet-friendly, with homes, businesses and parks that are deemed welcoming. It hopes many more will follow the example of Nashville, which has a pet “relief area” at its airport and a dog park at its hockey arena.

There is, of course, a vested interest here: a better world for pets also means a better world for Mars. Should the international pet population continue to swell, it’s a reasonable bet that its sales will, too.

“We are a business, and we are absolutely unapologetic about that,” says Moutault. “I don’t pretend we’re not; we are. We are a business, and we are, thankfully, successful, growing, developing.”

The firm has its fair share of critics. Mars “profits at the expense of animals and the people who care about them”, said Daphna Nachminovitch, senior vice-president at the animal rights group Peta, who accused it of “making vet care more expensive and less accessible”.

In the UK, where Mars is one of the biggest owners of veterinary practices, rising pet-care prices have put the industry on a collision course with the country’s anti-trust watchdog. The Competition and Markets Authority is investigating whether pet owners are overpaying for medicines and asking if large, integrated vet groups “act in ways which reduce consumer choice”.

Academics have raised questions, too, about the environmental impact of mass pet food production. And Mars has faced a backlash over its decision to continue operating in Russia after that country’s invasion of Ukraine.

Mars pointed to its creation of a climate reformulation team, focused on increasing the use of less carbon-intense ingredients, which it says has already carried out “numerous reformulations” of recipes.

More broadly, Moutault insists that the company has a purpose beyond profits. The group is “advocating for the role of pets in society”, he said. You can actually be cynic[al] about that and say, ‘Well, do we really need that?’, [but] I actually think human beings are wired to care. There is an inherent satisfaction of caring for a pet. It’s an emotional reward that makes people feel good about themselves.”

Pushing back against those who believe his company is purely encouraging the pet boom for its own gain, Moutault argues there are “countless” benefits of having an animal – and that many sit hand-in-paw with Mars making money.

Take teeth. While oral hygiene has “massively evolved” for humans, the development has been less advanced for pets. Mars vet hospitals are offering plans with yearly dental check-ups, in a bid to reduce the chance of tooth removals. “That’s what I call holistic value creation,” he says: animals in less pain, pets that live longer and Mars, rather than charging for one tooth-extraction appointment, capitalizing on multiple check-ups.

For similar reasons, Moutault, claims the company is also trying to help overweight pets. “The owners struggle to see that because they themselves, sometimes, are a little bit overweight, if I may say,” he says. Mars “should have no interest” in tackling this – after all, it might sell less food – but it’s “absolutely the right thing to do”.

Staff at its vet clinics are encouraged to have “very difficult” conversations with pet owners about exercise and portion sizes. Mars is also developing kibble which is lower in calories.

He also points to the human benefits – both psychological and physical – of owning an animal. “If I was very cynical,” Moutault suggests, “I would say, ‘Well, I should ask the government to recognize the fact that we are reducing, actually, healthcare costs for a big part of the human beings who have pets.’”

Few owners of cats and dogs have thought costs were falling in recent years when stocking up on supplies, or counting the zeros on the latest vet bill, however. Are they really getting a fair deal?

Moutault, acknowledges that Mars, a giant in both the pet food and vet care markets, was “very impacted” by inflation, before pushing back. Pet owners have “way more options than they’ve ever had”, he says, claiming there is a “very, very large and wide” range of prices around.

Today people are “more and more willing to actually do more for their pets”, according to Moutault, and there are more and more options available. We are sitting inside a 24-hour pet hospital, with MRI and CT scanners, an intensive care unit, recovery and oxygenated cages, and surgery suites.

Doing more often requires spending more. “Obviously some people feel compelled to do whatever it takes. Others are saying, ‘Well, no, there is a limit to what I can do,’” Moutault says, allowing that this “creates, potentially, a perception” of rising vet prices.

“So do they have a fair deal? I think it’s very clear, and we are very clear, that taking a pet is a commitment,” says Moutault. “You can’t always assume that your pet is going to be healthy.

“And trying to develop this consciousness, that you have to kind of anticipate and prepare for that, I think, is an evolution that we want to bring to the pet ownership culture in a way: that you have to anticipate for some of these things happening.”

Big pet goes to great lengths to win over owners, and turn them into reliable customers. A few miles up the road from the hospital, inside a sensory laboratory, a panel of 10 people is tasked with breaking down the smell of certain food samples by considering about 130 different aromatic notes. Is there a whiff of a certain meat, perhaps? Or a specific fruit?

Such samples are examined in forensic detail under microscopes. These labs – inside the Mars Petcare global innovation center – are not scrutinizing meals from a Michelin-starred restaurant, but kibble.

“We’re not asking everybody to agree with us,” Montault says of the company’s case for pet ownership. “In some cases, it enables us to innovate and create propositions that are incredibly helpful for pet owners. In some cases, others would have the point of view that this is going too far.

“It is their judgment. At the end of the day, the consumer votes.”