Elizabeth Brown spared no expense in seeking treatment for Maggie, her yellow Labrador retriever who was diagnosed with cancer in 2003. Radiation treatments and surgeries added up to more than $4,200 before Maggie died in 2008.

The experience prompted Brown to buy a pet health insurance policy for $90 a month when she later brought home a puppy named Caramel.

Faced with the increasing price of medical care, more pet owners are now pulling out insurance cards when visiting the veterinary’s office.

Pet health insurance has been available in the United States for nearly 30 years, but expanded veterinary treatments and changing attitudes toward the family pet have bolstered the number of policies over the past decade, even during the economic downturn.

“The humanization of pets is driving it, as people are more likely to treat pets as four-legged members of their family,” said Grant Biniasz, a spokesman for VPI Pet Insurance based in Brea, Calif., the largest pet insurance provider in the nation.

Pet insurance has grown at a glacial pace in the U.S., but it has gained speed in the past decade. Three percent of the nation’s 78 million dogs and 1 percent of its 93 million cats are now covered, according to a recent American Pet Products Association estimate. That’s up from 1 percent of dogs and virtually no cats covered in 1998.

Nestle Purina PetCare believes that eventually 10 percent of U.S. pets will be covered by insurance.

Changes in people’s social support systems – higher divorce rates, fewer children, and people living farther away from their families – has helped drive this trend, said James Serpell, a veterinary ethics professor at the University of Pennsylvania’s School of Veterinary Medicine.

“We’re using animals to replace what we’re losing in human social relationships,” he said.

With that evolution, pet owners now expect medical care for their pets to match medical care for themselves.

“People ask now, ‘Why can’t my dog get dialysis?’ People increasingly think health care they get from their vets should be like what they get for their children,” Serpell said.