Hi Stacey,
Pet Insurance is basically a way to prepare for any future accidents or illnesses that your dog may experience. The reason people opt for it is because many treatments and surgeries can be very expensive, and having an Insurer who will carry some of that cost (after you pay a deductible, let's say if the deductible is $100 a year, that means the first claim you make, you will have to pay $100 of it, and the insurer will pay the rest). There are different levels of coverage that each Insurance company will provide. Some insurance companies will cover a greater variety of accidents and illnesses, where others will only cover some. For sure, you need to research which accidents and illnesses are not covered, so you can choose a good provider. Generally, the higher premium accounts for greater coverage, so for example, if you're paying $20 a month, you may only be covered $1000 a year, which does not carry forward unused amounts. If you choose a higher level package at $60 a month, your coverage may be $5000 a year or more. Moreover, some insurers will give you that option to pay lower premiums if you are willing to pay a higher deductible.
Generally, if you foresee having difficulty paying a $1000+ surgery if your dog ever gets ill, or into an accident, then having insurance will be a good idea. Keep in mind that a lot of companies have policies for senior dogs, where the last time you can upgrade their policy is when they're 7 years old. This is the account for the fact that senior dogs are more prone to illness than a young puppy let's say. Also, if you upgrade after you find out your dog has a long term illness, it likely won't be covered under that new upgrade because it's "pre-existing" to the upgrade. This includes any symptoms your vet notes during your wellness visits, and the underwriters will be looking at those kind of details to see if your dog had pre-existing conditions.
I would definitely recommend having some kind of pet insurance, and to increase to a better package once your dog hits the 6-7 years of age as old age is likely to bring more illnesses for your dog.
Hope this helps!