LOS ANGELES — Dogs and cats have become part of the American family’s inner circle over the past 20 years, sleeping in their own beds or yours, eating food bought specially to help their digestion, drinking purified water and cuddling up in chairs on heated pads made to fend off arthritis.

In addition to veterinarians, some pets have their own groomers, trainers, sitters and occasional walkers.

All this suggests a bright future for an industry that has grown alongside the popularity of pets, expanding at a steady 4 percent to 6 percent a year since the American Pet Products Association started keeping records in 1996.

Americans spent an all-time high of $55.7 billion on their pets last year, and spending will creep close to $60 billion this year, association president and CEO Bob Vetere told buyers and exhibitors at the Global Pet Expo in Orlando, Fla., on Thursday.

The biggest chunk of 2013 spending, $21.6 billion, went for food – a lot of it more expensive, healthier grub. In 1996, total pet spending was just $21 billion. Adjusted for inflation, that’s $31.3 billion.

The humanization of our pets started about 20 years ago, Vetere said in a telephone interview. As pets accepted their new perch in the family, manufacturers introduced products that helped animals move from the backyard to the front room.

“What is feeding a large part of the growth now are the baby boomers who have become empty-nesters and are looking for some other ways to find the love and affection they used to get from their kids,” Vetere said.

“In the past, children were a reflection of us, and people are now extending that to their pets,” said Dr. Jessica Vogelsang, a San Diego veterinarian who owns the website pawcurious.com.