Charlie Brown, a 9-month-old terrier-pit bull mix with one eye, lives in the mailroom. Peachy, a 3-year-old blond terrier-pit bull mix, shares a manager’s office. Cats’ crates are stacked in the hallway.

The Washington Humane Society’s Northeast Washington shelter has been unusually crowded in recent weeks. Last month, the group took in 526 cats, 326 dogs and 22 other domestic animals there and at its second city shelter, but there were only 239 adoptions.

“Every time we empty cages, they fill right back up,” said Scott Giacoppo, vice president of external affairs. “Half the time, we don’t have the time to try and figure it out.”

Summertime always brings an influx of animals — especially kittens — to shelters across the country, experts said. Cats usually start to give birth in the spring, and owners often wait a few weeks to try to raise the litters before realizing that it’s too much for them to handle. Or owners go on vacation and can’t afford to board their animals or hire a petsitter, so they surrender their pets to a shelter.

The Humane Society’s shelters are also busier because of a change in euthanasia policies made in late 2007, after Lisa LaFontaine became president and chief executive.

Previously, all pit bulls — including Charlie Brown and Peachy — would have been euthanized. In 2006, 26 percent of animals left the shelter alive. Today, it’s 85 percent, and euthanasia is a last resort.

“We want all of them to get a second chance,” LaFontaine said, adding that she doesn’t mind crowding. “That’s a problem that I welcome, because it means we’re saving lives.”

The society is also doing more to help owners keep their pets.

In a survey with the Humane Society last year, the American Society for the Prevention of Cruelty to Animals found that most large dogs in the District were given up because of housing reasons, according to Alicia Guidi, manager of the society’s “Pets at Home” program.

In response, Guidi is working with lawyers, landlords, owners and a pet-friendly real-estate agent to try to change property restrictions. The program focuses on Southeast Washington, where Guidi says large dogs are at the highest risk of being surrendered.

“This is a vital piece of keeping animals home,” said Emily Weiss, the ASPCA’s vice president of shelter research and development. “They don’t need to be [in shelters] — people want them home.”

The problem isn’t unique to the Washington Humane Society, which operates facilities on Georgia Avenue NW and New York Avenue NE and provides the District’s animal-control services.

“We’re full to the rafters,” said Neil Trent, president and chief executive of the Animal Welfare League of Arlington.

“We are absolutely full with cats,” said Patrick Cole, director of communications and outreach for the Animal Welfare League of Alexandria.

At the Washington Animal Rescue League, 582 cats and dogs have been adopted since June 1, according to chief communications officer Matt Williams. It’s hoping that 800 animals will be adopted by the end of the month as part of an ASPCA challenge.

Last month, 248 animals at the Montgomery County Humane Society were adopted, but 906 were brought in, according to B.J. Altschul, external relations director.

Capacity at the Fairfax County Animal Shelter has been limited recently by a renovation project, according to Kristen Auerbach, director of communications and outreach. The shelter is relying on foster homes and rescue partners.

Although workers at the Washington Humane Society say sharing space with animals sometimes makes it difficult to get work done, they learn a lot about the personalities and preferences of the furry office mates.

Operations manager Jess Townsend’s small office doubles as Peachy’s house. The dog, who came to the shelter sick and emaciated, alternated between peering out of the gated door, stretching her neck out for a pat, and jumping into Townsend’s lap one day last week.

“It’s amazing what you can figure out to make do when you need to,” Townsend said as she scratched Peachy’s ears. “You’ve got to get creative.”

Alison Coates, a behavior and adoption counselor, balanced a laptop while the kittens next to her eyed dangling computer cords. One often meowed at her.

“It was nice to have a kind of conversation with the cat,” she said, laughing.