I checked into it long time ago. Makes little sense if you have a savings account for emergencies. I found there were deductibles and limits to the plans available. And like with all insurance, they will be happy to collect every month but you have to chase after them to get paid. Generally dogs are healthy early in life and if they get a bad illness when they are older, IMHO you have to say good bye not just for financial reasons but also in fairness to the dog.
I also see people that want only the "best" for their pet, which often translates to high vet bills. Most vets will upsell all day long if you are ready for it. In my area people sometimes boast with their vet bills, like Ferrari guys do with their maintenance bills.
G