Pet insurance can help offset the costs of paying a veterinarian to diagnose, treat, and manage a pet’s illness or injury. An unexpected illness or injury can happen at any time. Pet owners will probably incur at least one $2,000 to $4,000 bill for emergency pet care at some point during their pet’s lifetime, says Louise Murray, D.V.M., a veterinarian and vice president of the ASPCA’s Bergh Memorial Animal Hospital in New York City.

When we investigated this coverage, we found deciding whether or not to buy the insurance can be a tough call. Many policies may not be worth the cost over many years for a generally healthy animal. But if you're unlucky enough to have a pet with a costly chronic condition or illness, or a young animal in need of major care, we found you could get a positive payout from pet insurance if your pet develops the condition while covered.

If you’re considering a policy, look for free quotes, terms and conditions, and a sample policy on insurers’ websites. Consider coverage with simple, percentage-based payouts and no reliance on judgments of what’s “reasonable,” to avoid your own future headaches. Find out how your premiums might increase as your pet ages.

Here are some other surprising tidbits about pet insurance to consider:

1. Your Employer Might Offer Pet Insurance as a Benefit

As one of the fastest-growing voluntary employee benefits, one in three Fortune 500 companies now offer as pet insurance. More than 3,800 companies and organizations have added Veterinary Pet Insurance (a Nationwide Insurance company) to their benefits portfolio, including Chipotle Mexican Grill, Deloitte LLP, Delta Airlines, Hewlett-Packard, Microsoft, T-Mobile, UPS, and Xerox, according to VPI.

Some companies are subsidizing a percentage of their employee's cost, with several companies now paying as much as 100 percent of their employee's pet insurance premiums (you'll still owe additional costs, like co-pays).

2. It's Not Just for Cats and Dogs

At least one company offers policies for birds, as well as "exotic" pets that include amphibians, chameleons, chinchillas, ferrets, geckos, gerbils, goats, guinea pigs, hamsters, hedgehogs, iguanas, lizards, mice, opossums, potbellied pigs, rats, rabbits, snakes tortoises, and turtles.

Since so few companies offer coverage for our feathered friends and "exotic" pets, however, you can't compare several policies, so you'll have to take–or leave–its coverage.  

Several companies cover horses, but you may have to pair it with the company's mortality coverage (essentially horse life insurance), and the amount you'll pay and the coverage you can get may depend on the horse's age, breed, and other criteria.

3. Discounts Might Be Available

Membership in some affinity groups may provide you with breaks on pet insurance premiums. Healthy Paws, for example, provides a 10 percent lifetime discount to AAA members. PetPlan gives AARP members and active-duty or retired military personnel a 10 percent discount if they sign up for a plan online, or 5 percent if they buy a plan by phone.

Keep in mind, however, that these plans might not be the best choice in your situation. You still have to compare premiums, cost sharing, and exclusions to decide if a plan is right for you. You can always add some money to an emergency account to cover unexpected pet costs instead.

4. Older Pets Can Be Covered

Many companies will insure older pets, but age does matter. ASPCA Pet Health Insurance won't cover illnesses in dogs over 12 and cats over 14. Healthy Paws and Trupanion will cover pets for their lifetime, but you have to enroll them before their 14th birthday. Figo, which dubs itself the first cloud-based pet insurance, has no age limit.

But you'll generally pay more to insure older pets, and you may receive less coverage. For example, although the ASPCA doesn't cover illnesses in older pets, it will provide some coverage for accidents.

At any age, pure-bred animals will cost more to insure than mutts, and dogs are more expensive than cats.

5. Paying More for Routine Care Coverage Isn't Worth It

Many plans add "wellness" coverage that covers routine care like annual exams and vaccines. We found it's generally not worth the cost.

What goes in their bellies likely costs you more than routine vet care. Dogs gobble up about $270 of dog food annually, while routine vet visits for dogs total $235 a year. Cats consume $245 in grub annually; routine vet visits for cats average $196 a year.

Unexpected bills are, of course, the budget-busters. Surgical costs for dogs, for example, average around $550 annually; cats, $400. And serious accidents or illnesses can be many times that amount. We profiled a couple who paid $6,500 to repair their cat's leg after he had a run-in with some mattress springs.

Here's more about how to decide if pet insurance is right for you.