I've never done the pet insurance. My logic:
Pet Insurance - pay out $XX per month on the premiums. If the pet gets sick, hopefully all will be paid for by insurance. If the pet doesn't get sick, that money is gone.
Save it myself - put away $XX per month for vet bills. If the pet gets sick, use every bit needed. If the pet doesn't get sick, I have that much more money in reserve.
With multiple pets, it's worked well for me. But, I have also done the same for vehicle and household "emergencies", so I have enough being put away each month to handle things as they occur. That means I'm not cutting into my pet funds to pay for the $600 motherboard in the SUV, etc.