The way Trupanion works is, first, pre existing conditions are excluded. After that, you set your own deductible. The higher the deductible, the lower the monthly premium. After you meet the deductible for any one condition, then they pay 90% of all subsequent claims or medication for that condition for the life of the dog.
Claims are submitted on line along with supporting documentation. They immediately acknowledge receipt of claim, sometimes they call the vet, and usually they directly credit my checking account within a few days.
My dog has had a couple of issues, one of which required a CT scan, which they paid for. Last time I did the math, I had recovered about as much in benefits as I had paid in over the years. So it has been break even. However, it's nice to know that if I do have a problem, I can make a decision regarding what's best for the dog instead of "is she worth the money."