Our cat is not the sharpest knife in the drawer so to speak... He ate a poisonous plant and the vet bills cost us about $3,000. After that incident we decided to get pet insurance. We spent a while decided which service to go with and settled on Trupanion. Only about a month after we signed up our cat got into trouble again after swallowing a cat toy. The bill was $6,000 this time! Even though we had only been signed up with Trupanion for a month and had paid a single down payment of about $20, they covered 90% of the total bill! There were a few items on the list that were not covered, like standard check ups, but all in all we only ended up paying about $800 instead of $6,000. I can honestly say that Trupanion saved my cats life... paying 6k to save our cat was just not an option for us.
The only negative that I can speak of is that I did indeed have to pay the six thousand dollars upfront and then had to wait an agonizing week before Trupanion confirmed that they would cover us. It took about a month and a half until the insurance check came and was also pretty stressful floating $6,000 in debt while waiting.
These are small complaints though, my cat is alive and my savings account is for the most part intact.
I would highly recommend them.