Americans are increasingly treating their pets as members of the family. So it's not surprising that an increasing number of "pet parents" are seeking sophisticated medical treatments for their animals.

Enter pet health insurance, marketed as a way to help defray rising veterinary expenses and avoid "economic euthanasia" — the necessity of putting a pet down because the owner can't afford treatment. More than 2 million pets in the United States and Canada (most of them in the U.S.) were insured at the end of 2017, up about 17 percent from the year before, according to the North American Pet Health Insurance Association.

But consumer advocates said that pet owners should make sure they understand how the policies work before buying them.

J. Robert Hunter, director of insurance with the Consumer Federation of America, said pet owners should bring a healthy skepticism when shopping for pet insurance. Purchase of the product is "often motivated by a combination of love and fear," he said. "So the buyer may be particularly vulnerable."

Details vary by insurer and policy, but premiums for pet insurance typically depend on factors like the cost of veterinary care where you live and the age and breed of the pet. The average annual premium for "accident and illness" coverage was $516 per pet in 2017, while the average claim paid was $278, according to the pet health insurance association.

Jeff Blyskal, a senior writer with Consumers' Checkbook, a nonprofit group that rates services in major urban markets, said pet owners should compare policies with a critical eye. When years of payments are taken into account, he said, buying insurance could end up being more expensive for some pet owners than going without it, if their animal doesn't require much care.

Pet policies typically don't cover pre-existing conditions, Blyskal said, so premiums are generally lower when your pet is young and healthy. Even if you start early, though, you may end up paying more over time, he said, because some policies raise premiums as pets get older. This can increase costs substantially, he said, and cause owners to drop their policies as the animals get older — just when they are more likely to need the coverage.

The expenses tied to pet health coverage usually include not only a regular premium but also other out-of-pocket costs, like a deductible — an amount that you must pay before insurance begins paying. Insurance may cover less than 100 percent of costs after the deductible, so you will still have to pay for part of the treatment. Some policies may cap payments, so ask if there's a limit.

Rob Jackson, chief executive of Healthy Paws Pet Insurance, said insurance could protect against budget-busting events costing thousands of dollars.

One way to pay lower premiums, and possibly get broader coverage, is to buy pet insurance through your employer. Eleven percent of U.S. employers offer pet health insurance benefits, according to a 2018 survey by the Society for Human Resource Management. It's uncommon for employers to contribute to the cost of premiums, as they do with human health insurance. But insurers may give employees a break on premiums, or offer better coverage, because their marketing costs are lower.

Ann Carrns writes for the New York Times.