Pets are more popular than ever. Roughly two-thirds of American homes have at least one pet, up from 56% in 1988, according to the American Pet Products Association, and Americans spent $136.8 billion on their pets in 2022, up from $123.6 billion in 2021. An estimated 91 million households in Europe own at least one pet, an increase of 20 million over the past decade. The pet population in India hit 31 million in 2021, up from 10 million in 2011.

And our pets are becoming ever more like us — or at least, that seems to be our goal. We pamper them with customized nutrition plans and knapsack carriers, dog hydrotherapy and stays in boutique cat hotels. At All the Best, a high-end pet store chain in Seattle, the most popular items are feline and canine enrichment toys, designed to stimulate them and bring happiness to animals that increasingly "are lying around alone and bored," said Annie McCall, the chain's marketing director.

Now some animal welfare ethicists and veterinary scientists are wondering if, in our efforts to humanize our pets, we've gone too far. The more we treat pets like people, they argue, the more constrained and dependent on us our pets' lives have become, and the more health and behavioral issues our pets develop.

"We now view pets not only as family members but as equivalent to children," said James Serpell, an emeritus professor of ethics and animal welfare at the University of Pennsylvania School of Veterinary Medicine. "The problem is, dogs and cats are not children, and owners have become increasingly protective and restrictive. So animals are not able to express their own doggy and catty natures as freely as they might."

The health risks begin with breeding, of course. One of the most popular dog breeds in the United States is the French bulldog, a member of the brachycephalic family of flat-faced dogs that bond well with people but have trouble breathing, among other severe health problems.

But we are also changing our animals' relationship to their surroundings. Out of concerns about bird predation, many cats now spend their entire lives inside. Until the late 1970s, even city dogs spent most of their time outdoors, either in backyards or roaming unleashed around the neighborhood. Now, said Jessica Pierce, a bioethicist in Colorado whose work focuses on animal-human relationships, "the unleashed and loose dog is considered against the natural order of things."

One of the fastest growing market segments is the so-called pet confinement sector, which includes crates and indoor fencing, as well as head harnesses and electronic collars. "The level of constraint that dogs face is profound," Pierce said. Although dogs several decades ago were more likely to be hit by cars, she added, "those risks were outweighed by the freedom of experience and movement."

The modern pet paradox, in a nutshell: "Owners don't want dogs to act like dogs." Serpell said.

While dogs are allowed in an ever-increasing number of human spaces — restaurants, offices, stores, hotels, as well as more parks with designated dog runs — their growing presence has not translated into greater independence.

The confinement and isolation, in turn, have bred an increase in animal separation anxiety and aggression, Serpell said. Roughly 60% of cats and dogs are now overweight or obese. And due in part to the burden and expense of modern pet ownership — veterinary fees, pet sitters, boarding costs — more people are abandoning animals to animal shelters, leading to higher rates of euthanasia. In 2023, more than 359,000 dogs were euthanized at shelters, a five-year high, according to Shelter Animals Count, an animal advocacy group.

"We're at an odd moment of obsession with pets," Pierce said. "There are too many of them and we keep them too intensively. It's not good for us and it's not good for them."

Granted, taming an animal has always meant striking a balance between its nature and ours. "Defining freedom to a dog, an animal that has been domesticated artificially and selected by humans for so long, is a really interesting puzzle," said Alexandra Horowitz, a canine cognition researcher at Barnard College.

She drew a contrast with free-ranging dogs, a category to which most of the world's estimated 900 million dogs belong. Free-roaming canines lead shorter lives and have no guarantee of food, Horowitz noted, but they do get to make all their own choices. "That is an interesting model for us to look at — thinking about how to make a dog's life more rich with choices so they are not just captive to our caprices all the time, while not endangering society at large," she said.

In recent years, Scandinavian countries have started to ban the breeding of some dog breeds that are particularly prone to disease, such as the Cavalier King Charles spaniel. In Sweden it is illegal to leave pets alone at home for extended periods of time; in both Sweden and Finland, crating animals in the home is illegal in most cases.

But whether these animal welfare policies reconcile or reinforce the fundamental paradox of modern pet keeping is unclear, said Harold Herzog, an emeritus psychology professor at Western Carolina University who studies animal-human relations. "The more we view dogs and cats as autonomous creatures, the less we can justify owning them as pets," he said.

A few years ago, Herzog vacationed on the island of Tobago, and spent much of the time watching the stray dogs that roamed the landscape. "I asked myself: 'Would I rather live in Manhattan as a pampered dog, or would I rather be a dog in Tobago hanging out with my friends?'" Herzog said. He concluded: "I'd rather be a dog in Tobago."

That's not a practical option for most people, or necessarily good for the Tobagos of the world. Instead, for the modern pet owner, Serpell offered this advice: "By all means, enjoy your dog's companionship. But dogs are not people. Get to know the animal from its own perspective instead of forcing them to comply with yours. It enables you to vicariously experience the life of another being."

This article originally appeared in The New York Times.