We have Pets Best Insurance. Prior to getting our lab puppy from AgVet, we asked our local Vet what Pet Insurance she'd recommend...she immediately mentioned Pets Best.
I too would recommend getting the policy when they are young. Candidly, we got it because this puppy is now 82 pounds, and he loves to run. A friend of ours, who is a retired vet, saw him run recently and she asked me, "Do you have Pet Insurance?" I told her we did and then asked why. She replied, "he'll blow out his ACL someday."
Hoping that's not the case.