Fido has a fever, and the veterinarian wants to conduct a spate of expensive diagnostic tests.

What's a pet lover to do? Tap the dog's health insurance policy, of course.

Thousands of animal owners have turned to pet insurance in recent years to cover their critters' unexpected ailments. And the service is so popular that some U.S. companies offer discounted pet insurance as a "voluntary benefit" to their employees.

Dallas-based Blockbuster, for example, made pet insurance available to its workers last year - along with policies that cover their cars, homes and long-term care.

"We rolled out the pet insurance program as part of an overall flexible-benefit offering to our employees about a year and a half ago," said Dan Satterthwaite, Blockbuster's senior vice president of corporate human resources. "We've had a few hundred people sign up."

Blockbuster's provider, California-based Veterinary Pet Insurance, boasted a 125 percent increase this year in employment-based policies - with more than 400 companies now offering pet benefits. The company claims more than 80 percent of pet policies in the United States.

"Pets have gone from being outdoor animals, to living in the house, now to sleeping in the beds," said David Goodnight, a Dallas veterinarian who is the provider's executive vice president of business development. "As a consequence of that, now people are paying a lot more attention to the health care of their pets."

For businesses, pet insurance represents a perk that can score points with workers at no cost to the employer.

The policies are usually included in a range of so-called voluntary benefits that employees can select to pay on their own - often taking advantage of a group discount.

A 2001 study by MetLife found that nearly 90 percent of employers offer their work force such benefits. Although the most common are various types of insurance, some companies also make available help such as legal, financial planning and concierge services, according to the study.

Miller Brewing Co. allows workers to buy a variety of insurance policies - including pet coverage - as well as legal advice and access to equity loans.

The benefits have been popular since the company introduced them four years ago, said Sue Rowe, employee programs manager.

"It's looked at as a retention tool," Rowe said. "It's the soft benefits that help make this a wonderful place to work."

The pet insurance functions in a manner similar to traditional health-care policies. Here's how it usually works:

An employer signs on with a pet insurance provider, arranging for a discount for any employees who want coverage for their animals. Interested workers choose a policy and pay the full premium - often through payroll deduction.

Prices vary by community and depend on the animal.

When a pet gets sick or injured, the employee can use the insurance benefits to pay veterinarians' bills - less a $50 deductible. Routine care, such as vaccinations and teeth cleaning, aren't covered unless the worker buys a more comprehensive policy.

Blockbuster's Satterthwaite said some employees have been amused by the pet policies, especially when the company insured "Carl and Ray," its rabbit and guinea pig marketing mascots. But those with older pets or exotic animals like the insurance option.

"It does get giggles every once in a while," Satterthwaite said.

"But for people that have pets, they are the ones who really know how much a pet can cost."