Angie Best-Boss has tried changing litter boxes, types of litter, brands of litter. But something has gone terribly wrong with Tiger.

"I loathe my cat," said the freelance writer in New Palestine, Ind. "Actually, loathe might be too weak of a word." At a time when many people are scrimping on themselves to indulge their animals, the love is lost for owners of infuriating pets.

Still, many can't bring themselves to dump their animals in shelters. Instead, they pay sky-high vet bills for intervention that doesn't work.

So how does a human make peace with a problem pet? Venting helps, said an expert.

"We all know couples who look like they like to fight. They let fights happen because, it seems, they're getting something out of it. Some people have that relationship with their pets," said psychologist Stephanie LaFarge of the American Society for the Prevention of Cruelty to Animals.

About 5 percent of the dogs and cats placed in homes by the ASPCA's adoption center in New York City last year were returned, said its senior vice president, Gail Buchwald.