"I don't have kids, and I've intentionally decided that while I want to have kids one day, I'm not at that point in my life, and I think a lot of millennials here in D.C. are kind of in that same boat, but you still enjoy having something to take care of," she said, feeding Lucy some treats.

Thirty-one-year-old Jessica Evans lives in a single-family row house in Washington, D.C., with Lucy, a dog, and Casper, a cat. She calls them her "fur children."

A full 73 percent of millennials currently own a pet, according to the American Pet Products Association. That is a larger share than any other demographic. For buyers it's even bigger. A whopping 89 percent of millennials who bought a home so far this year own a pet, according to Realtor.com.

Luxury landlords have been catering to this millennial trend for years, putting in dog runs on rental tower roofs and pet salons off lobbies. Now more millennials are buying homes, and seeking the same amenities.

Millennials are having a love affair with pets — so much so that they're often putting their furry friends' needs at the top of their list when shopping for a home .

But taking care of her pets, especially Lucy, meant selling her condo and buying a single-family home.

"I loved living in the downtown area in a condo. It was great, very convenient, I didn't have housework, but the one thing that was really missing was my dog's happiness," said Evans.

Keeping pets happy appears to be a millennial priority. For this demographic, 79 percent of pet-owning homebuyers who closed on a property this year said they would pass up an otherwise perfect home if it didn't meet the needs of their pets, according to a Realtor.com survey.

Evans knows this firsthand, because she is also a real estate agent with mostly millennial clients. On their wish lists: first and foremost, outdoor space — a yard or at least a park within walking distance.

"The big thing with cats is where is their litter box going to go? I think with any house or condo, that's a big decision," she added.

And owners with older pets often have concerns about stairs. More affluent buyers want a dog grooming station in the mud room. Also, being near pet-friendly restaurants and pet supply stores is a big plus, especially for young urban buyers who might not have a car.

And once millennials purchase a home, they often put big bucks into upgrades for their pets. Evans put $12,000 into her row house, adding a higher fence so her pets couldn't jump out and other pets couldn't jump in. She also added a modern pet door and renovated the basement bathroom for Lucy, even though the basement itself is unfinished.

"I wanted her to have her own shower so that I wouldn't have to clean mine after washing her in it," said Evans.

She just wanted her house to be pet-friendly overall, not just for herself but for her friends, most of whom also have pets.

"I think I tend to connect more with other people with pets because we can do pet-friendly things together," said Evans, adding that some of her clients who don't have pets are also interested in pet amenities because they've been waiting to own a house first, so they can get a pet.