Insurance is great and you shouldn't own a pet without it. But, most insurance won't cover certain breeds. My British Bulldog for example can't be covered I guess they have too many problems.

I used to have a dog that didn't have insurance and she got quite sick. I tried to get insurance so that future vet bills would be covered. But I was turned down because she already had health problems. But it might work differently in the states than in Canada.