If your priorities are hereditary-condition coverage + predictable premiums, I’d put Trupanion at the top of the list.
My ranking
| Insurer | Hereditary/congenital conditions | Premium predictability | Best for |
|---|
| Trupanion | Excellent | Excellent | Purebred dogs where long-term predictability matters |
| Embrace | Excellent | Good | Broader coverage and more customization |
| Pets Best | Excellent | Fair–Good | Lower initial premiums / flexibility |
| Figo | Excellent | Good | Value and customizable coverage |
Why Trupanion stands out: it covers hereditary and congenital conditions, including breed-associated conditions such as hip dysplasia, and has no annual or lifetime payout limits. Most importantly for your second criterion, its pricing isn't increased simply because your dog has another birthday. Instead, rates can still change because of factors such as veterinary-cost inflation and geographic/statewide rate adjustments.
Its unusual per-condition deductible can also be valuable for a purebred dog. Once you've met the deductible for a particular chronic/hereditary condition, you don't pay that deductible again for that condition over the dog's lifetime.
The important caveat
No pet insurer can truly promise a permanently fixed premium. Trupanion explicitly says rates can adjust for things such as increases in veterinary costs and other pricing factors. So I'd interpret "predictable" as less dependent on your dog's aging or claims history, rather than "guaranteed not to rise."
Embrace is probably my #2. It explicitly covers hereditary, congenital, and breed-specific conditions without an extra hereditary-condition rider, but it acknowledges that premiums can increase with your dog's age, breed, location, and other factors.
One other consideration: Trupanion is generally more expensive upfront, but its structure is particularly attractive if you're insuring a breed with meaningful lifetime risk of expensive hereditary disease. A cheaper policy can become less attractive if it has annual limits, resetting deductibles, or age-related premium increases.
If you tell me your dog's breed, age, ZIP code, and whether you prefer a $250/$500/$1,000 deductible, I can compare the most suitable policies and identify which is likely to give you the best lifetime value.