I'm with Trupanion. They cover most hereditary conditions, injuries and illnesses, but not routine wellness visits, vaccines and similar preventative care (ie, routine dental cleanings). I figure I can easily budget for the routine things, but the bigger unexpected items are where a problem would arise.
Trupanion is a Canadian company-- they operate in some areas of the States, but they aren't nationwide yet.
I've posted this link once before, but here's a tool on Trupanion's site that compares different insurance plans.
http://www.trupanionpetinsurance.com...omparison.aspx