Camera poised, Tomoaki Kasuga peers eagerly forward as Coco takes her first swimming lesson. When she successfully catches a tennis ball and swims toward him, Kasuga's nervous face melts into a broad smile.

Coco, a 6-month-old golden retriever, is among a surging number of dogs in Japan enjoying a lifestyle many humans could only envy -- weekend spa visits, pasta lunches at open-air cafes, designer clothing.

The boom, experts note, comes as the nation's birthrate keeps plunging and the number of Japanese children continues to drop. According to pet industry figures, Japanese families now have more than 19 million pet dogs and cats, exceeding the number of Japanese children under 15, which just hit a new low of 17.8 million.

Kasuga, 48, president of a high-tech firm who lives with his wife and mother, had brought his pet to Dog Petit Resort "Joker," which offers hot tubs, therapy pools and a beauty salon for dogs. "Coco-chan is our princess," he said. "Since she came to our house, our life has been revolving around her."

Japanese, many inspired by hit TV commercials for a loan company featuring a doe-eyed Chihuahua, bought more than 1.5 million dogs last year by industry count -- mostly Chihuahuas, miniature dachshunds and other dogs small enough to fit into Japan's cramped homes.

Catering to the 11.1 million canines is a huge industry, estimated at more than $9 billion.

The fashion-conscious can walk their dogs with a Louis Vuitton leather leash and a neck cuff for a combined $540, or use a $1,730 carrying case. For those leaving their pets behind during business trips, dog hotels and dog-sitters are readily available.

For gourmet dogs, Internet shopping sites offer heat-and-serve creamy pasta with Parmesan cheese, corn, green peas and pork or orange-flavored herb chicken fillet. For dessert, dog bakeries prepare muffins and cookies or a birthday cake topped with strawberries and cream.

Analysts say the boom reflects a changing attitude toward pets in the world's fastest-aging society, where the birthrate is at its lowest ever -- 1.29 per woman.

In a country where people take off their shoes at a home's entrance and live in tatami-mat rooms, it was long unthinkable for dogs to be kept inside. But that has changed as traditional Japanese homes have been replaced by Westernized townhouses with wood floors.

Families have split into smaller units, with aging parents often living alone, and many Japanese have turned to dogs to fill out their thinning family bonds, said Katsuo Mochizuki, with the Pet Food Manufacturers Association of Japan.

"As we've gone through more than a decade of economic slump, facing social uncertainty and stressful city life, many Japanese have found dogs an answer to relieve stress and feel warmth at home," he said. "Couples with grown-up children have also found dogs as a substitute."

Recent surveys suggest dogs are most often owned by people over 45.

More apartment complexes tolerate pets, some providing a wall-mounted panel for cats to exercise their claws. More city parks have dog runs, and more open-air restaurants and cafes will serve a dog a bowl of water under its owner's table.

But although Japanese have proven good at cleaning up after their dogs in public, most restaurants and public facilities still admit only seeing-eye and other aide dogs.

"We don't allow pet dogs inside our office buildings because we can never be sure how well trained they are," said Kensuke Kimura, a Tokyo Metropolitan Government official in charge of pets. "Even if a keeper considers a pet dog a family member, the general public's tolerance level hasn't gone that high."

The dark side of the pet craze is the nearly 380,000 abandoned dogs and cats destroyed last year, according to Environment Ministry statistics.

"The current pet boom is very dangerous," said Chizuko Yamaguchi, a veterinary inspector at the Japan Animal Welfare Society. "To many people, their dogs are the same as their designer-brand bags. Dogs are treated as objects, a fashion, rather than living creatures."

Tomoaki Kasuga and his mother watch Coco, their 6-month-old golden retriever, take her first swimming lesson in a Tokyo pool.Coco, a beneficiary of the growing trend to treat pets to luxuries, takes a break from her swimming lesson.