Consumer Confidential: Be ready to fight if a pet insurer, like a people insurer, denies a valid claim

It's every pet owner's worst nightmare: Your beloved furry friend comes down with a serious, costly illness. That's why pet insurance in the United States has grown into a nearly $900 million business.

But, as with human health insurance, claims for critters frequently can be denied by insurers for a variety of reasons. Most often, it's because the illness is deemed a preexisting condition, which few pet policies will cover.

Challenging such denials can be frustrating, especially if your pet's medical needs are urgent.

That's where Pasadena, Calif., resident Samantha