If anything comes up through those test- it will be considered pre-existing. We used to have insurance you can get through AKC. Filed first claim and it was totally denied. It basically boiled down to a hereditary issue which equals pre-existing. Pet insurance is basically the same racket as our health insurance coverage. As posted above- "the house always wins"!
I have had experience with both scenarios and it's insurance for me!!! Had two dogs who were attacked by something in the state forest. Resulting vet bill was in excess of $3000 (and this was around 10 years ago). No insurance, so I had to find the money. First thing I did when I brought my current dog home was to insure her. Has paid dividends as in her first two years she had two visits to the emergency vet (which isn't cheap) for upwards of $1500 - $1800 each time. Our insurance paid, from memory, 80% of each bill.