Pre-existing conditions are any health conditions that first occurred before the pet insurance policy's start date (aka effective date). Anything that is documented on your pet's medical health record before you get pet insurance will likely be considered a pre-existing condition and will be excluded from coverage (meaning any claim you make on that condition will be denied).
We think this is a fair exclusion.Why do we think that? Because an insurance system that covers pre-existing conditions couldn't last for very long! That would allow people (or pet owners) to wait until they get sick before they got insurance - and then cancel it after they recover. If everybody did that, no insurance company could afford to exist! Insurance works because not everybody needs it at the same time (this is because of the "law of large numbers"). Sick pets (and wrecked cars and damaged homes) can be covered by insurance because people with healthy pets and no car accidents and undamaged homes are also paying into the insurance pool. Because pre-existing conditions are always excluded, you should get pet insurance as soon as possible for your pet! The longer you wait, the greater the chance your pet experiences a health issue that would be excluded from coverage.