The Sean Casey Animal Rescue in Windsor Terrace is overflowing with cats, and staff members say many shelters across the city face the same problem.

Spring and summer are the top breeding seasons for cats. Without enough people to take them in, many of the felines are left to wander the streets without homes.

One cat lover says she already has 14 rescued or adopted felines.

"It hurts that I can't pick them all up and take them home with me," says Laura Vona.

The shelter says it has rescued about 12,000 cats since it opened in 2004.

"We're reaching a point now where we can't take anymore and it's become a real hardship," says Sean Casey, who founded the shelter. "I spend half my day telling people 'I'm really sorry but I can't help you.'"

He says the shelter is limited by resources and space. Thousands of cats are available for adoption throughout the borough, Casey says, including 30 at his shelter.

He adds that now is a good time for anyone looking for a new pet to adopt.