The first time I saw him I knew I loved him. He was bounding in the street, tongue out, giant smile across his giant face, as happy as I had ever seen any four-legged creature. "Stop the car! Stop the car!" I yelled to my then-boyfriend, who didn't see the dog doing freedom love leaps about five feet from the car's hood. I opened the car door, and a then-55-pound pit bull "puppy" leapt right in, licking our faces like he had been waiting for us on that street corner forever.

Over the next few weeks, I'd see him chained up to a tree in the neighbor's yard. Someone had also put a thick, heavy chain around his neck and covered it in layers of duct tape, making him carry a bulky, grit-colored collar behind his already heavy head. I'd remark that "the nicest dog I had ever met" was lonely and sad, and I'd find excuses to walk over and soothe-talk him and wave my fingers through the chain-link fence in an imagined solidarity sign.

When the owner told me he was taking him to the Humane Society because he couldn't handle him, I knew I had to get him. Five years ago, a dog like him wouldn't make it. The guy wanted money for him, too much money, and a bunch of nice souls on the internet donated to his rescue funds.

Today, that giant dog is 85 pounds, and he is at my ex-boyfriend's house. But thanks to our arrangement, I will see Scoobi (his "given" name) this weekend, because for the past four years, we have shared joint custody of a dog. Scoobi gets constant devotion, and we each get to share the responsibilities that come with owning an 85-pound food-obsessed leash-staring walk-begging prone-to-sunburn dog who tries to sit in the lap of everyone he meets.

Dog ownership has changed over the years, which highlights one of the many reasons it's so hard to totally give him up. Since the 1960s, dog and cat ownership has quadrupled, reaching 150 million total cats and dogs in homes. Thirty-six percent of households have a dog. This year, we're likely to spend $60 billion on them in the U.S. alone. Yet it wasn't till the last two decades or so that dogs have become a big part of the family, leaping from the back yard hay pile to their owner's comfy bed.

David Grimm, author of Citizen Canine: Our Evolving Relationship with Cats and Dogs, attributes the change in pet-owner relationships to the shifting ways we live now. "Now you have a lot of people living just as couples without kids, you have empty nesters, you have huge divorce rates, people living by themselves. There's a real emptiness in our homes that cats and dogs have filled. This isn't fringe behavior to treat a pet like a member of the family. It's not the crazy cat lady or the crazy dog person. It's society."

Sharing a dog, "co-parenting," or having "joint custody," is increasingly common, though it's not recognized by law. Dogs, for the most part, are still considered "personal property," the sharing of which is considered by law like trading an old gym sock back and forth. But even the concept of dogs as purely property is slightly shifting.

Last year, in France, a new bill changed the definition of animals from "movable goods" to "living and feeling beings," ending what one lawyer described as a "legal gray area" for dogs and cats stuck in the middle of a custody battle. Of course, in the U.S., we're a little less open about legally categorizing pets as "feeling beings," yet there is a push to upgrade the legal status of dogs to "personhood," the same benefit corporations receive.

In a New York Times opinion piece in 2013, Gregory Berns, a professor of neuroecomonics at Emory University, argued that dogs are people, too, a discovery based on training and studying dogs with an MRI scanner that revealed they experience deep emotions. We must "reconsider treating them as property," he wrote.

So far, legal proceedings have been mixed. In some cases, judges have gone so far as to award visitation rights to owners for their dogs. But until laws about dogs change, it's up to the adult humans to determine what is in "the dog's best interest." Which, for Scoobi, means not one but two houses where food magically rains from above.