Mexico City, Mexico — Camila celebrated her first birthday in a blue-and-white striped dress with tulle appliques, playing with her guests in a room decorated with pink balloons, lilacs, and Hello Kitty posters.

When the cake arrived she barked at the single flickering candle, provoking a similar reaction from the Chihuahuas, French bulldogs, and Pomeranians in the room. "We've never had a female dog so we wanted to do something special with her," said Valery Palma, a single 35-year-old lawyer who owns Camila.

Over the last decade, the growth of Mexico's middle class has created a new market for fancy goods and services for dogs including clothing and accessory boutiques, spas, and restaurants with doggie snacks cooked by a pastry chef.

It's a startling cultural shift in a country where a dog's life has long meant days chained to the roof of the house. The 2000 film "Amores Perros" used the brutal treatment of dogs as a metaphor for the inhumanity of contemporary Mexican society. Mexico has more than 20 million dogs, many of them roaming the streets hunting for food in the trash or spending their days shut up in apartments by owners who see them simply as living burglar alarms.

Valery Palma blows out the candle on a dog friendly cake for her one-year-old dachshund Camila.

Last year, the problem gained international attention when authorities said five people had been killed by a pack of feral dogs in the Cerro de Estrella park in Iztapalapa, a poor eastern neighborhood of Mexico City. Authorities captured some 50 dogs near where the attacks took place and brought them to a pound, prompting demonstrations by animal rights activists that pushed officials to put the dogs up for adoption.

At the same time, a small and growing number of Mexicans are spending once unimaginable amounts on their canines. Many of the estimated 40 million Mexicans considered to be middle class are having fewer children than their parents did and, therefore, also have more disposable income.

"People are no longer having children at a young age because they can have a different lifestyle with luxuries they will no longer be able to afford once they have children," said Zorayda Morales, an analyst with De La Riva Group, a market research agency.

Palma, who has two dogs, spent $300 on the birthday party for 11 canines and 16 people, complete with cake, presents, and snacks, at a dog hotel featuring a gym and massage and aromatherapy services. "Today people invest in their dog," said animal behaviorist Renan Medina, one of the founders of MEDICAN, Mexico's first animal hospital with a hyperbaric chamber, used to accelerate the healing of wounds and infections.

"This goes beyond a trend," he said. "People see their dog as part of the family." Since 2008, sales of pet-related products have grown an average of 13 percent a year, to $2.2 billion last year, according to market research firm Euromonitor International.

"We're seeing the growth of this idea in which a dog is an alternative to children," said Raul Valadez Azua, a paleozoologist at the National Autonomous University in Mexico City. "On the one hand, they are people who feel that the economic obligations of having a family are too high. On the other hand, they have the resources to give a lot of care to a pet."

Dogs have become more popular and pampered in working-class areas, too. Neighborhood street markets feature ever-greater quantities of dog products such as shampoos, brushes, and elaborate leashes and collars.

"It doesn't depend on class, it depends on commitment, said Medina, the animal hospital founder. "People without a lot of money are sometimes better clients than the upper classes. Some show up and say, 'I don't have money, what can we do? I'm an upholsterer and I can reupholster your chairs in exchange for treatment.'"

At the other end of the income scale, owners of pure-bred dogs are being hit by robbery and kidnapping of animals worth thousands of dollars in some cases. Nurse Karla Gutierrez's dog walker was out with her 4-year-old golden retriever Hebe and several other dogs in February when two men held him up at gunpoint.

"They told him, 'the dogs,' and he let Hebe's leash go so she could run away, but my girl just curled up into a ball and they grabbed her and another golden," Gutierrez said. Gutierrez has since plastered her neighborhood with posters of Hebe, with the caption "Stolen."

"I am still crying for her almost every night," Gutierrez said. "I'm trying to live my normal life, playing soccer and riding my bike, but I can barely do it."