Washington ? Just because 2-year-old Ruben is a dog doesn’t mean he can’t send Christmas cards.

The Puggle from McLean, Va., a cross between a pug and a beagle, has already mailed seasons greetings to his canine friends and signed them with a paw print. His mother – that is, owner Mary Partlow Lauttamus – is knitting him a striped scarf that she plans to put under the tree, along with a new doggy-sized red sweater. He’s already received a box of homemade treats from his walker and a pull toy from a Brittany spaniel. And Santa Claus will drop off the piece de resistance: a new plush toy hedgehog with a distinctive squeak.

“Ruben is really a part of our family,” Lauttamus said. “He’s a good sport when it comes to all these things. He puts up with us.”

This holiday season, retailers are catering more than ever to the desire to pamper pets. Responding to what they see as the growing humanization of pets, retailers are finding that there’s great appeal in the kinds of gifts for pets that were once the sole domain of their owners, such as Christmas stockings, cashmere sweaters and educational toys.

“It’s no longer comfortable to reward these animals in pet terms,” said Bob Vetere, president of the American Pet Products Manufacturers Association, a trade group. Now the thinking is, “My dog means so much to me that I have to give him something that means something to me,” he said.

According to a recent APPMA survey, about 56 percent of dog owners and almost half of cat owners buy their pets Christmas gifts. Spending on pets is expected to reach $40.8 billion this year, almost double the amount spent in 1996.

Vetere said the growth is driven by two groups of pet owners – empty-nest baby boomers and dual-income couples with no children – who lavish their time, affection and disposable income on their animals. In this world, pets are people too.

Kartraice Hooper, of Washington D.C. cradled her 10-month-old Pomapoo, Noly, in her arms while shopping during a holiday party for Juicy Couture’s new line of canine-grooming products, Juicy Crittoure. Noly was stylishly dressed in a floral Elizabethan-style coat adorned with pearls. Hooper said she splurged on the $70 outfit the previous week.

“Is that bad?” she said, hugging her pooch. “It was getting cold, so I wanted to get her something.”

In the APPMA survey, Christmas ranked as the most popular holiday to give pets gifts. Though dogs and cats were the most likely recipients, 27 percent of bird owners also admitted to tucking a little something under the tree. Among people with reptiles, the number dropped to 10 percent.

Tracy Ryan, an associate professor of advertising research at Virginia Commonwealth University who has studied pet gifts, said owners have three main motivations, which mirror the roles we take on when giving to each other.

Most commonly, owners want to make their pets happy, or they feel a responsibility to provide for their pet’s needs, she said. But a surprising minority of people gave gifts to compensate for a guilty conscience, such as not walking the pet enough or not being able to spend time with it.