A pre-existing condition is an illness, injury or symptom your pet had before the policy started, even if it seemed minor at the time.
This is probably the single most important term to understand when it comes to pet insurance, because it affects what gets covered more than almost anything else.
If your pet has been seen by a vet for something, diagnosed with something, or shown symptoms of something before your policy started, that thing is likely to be treated as pre-existing by your insurer. And pre-existing conditions are almost always excluded from cover, at least initially.
It doesn't have to be something serious. A skin flare-up, a bout of diarrhea, a limp that the vet had a look at and said was probably nothing — all of those go onto your pet's vet records. A new insurer will look at those records when you take out a policy or make a claim, and anything on there that predates the policy could be flagged as pre-existing.
This is why getting pet insurance in place early, before anything goes onto your pet's records, makes such a practical difference. An eight week old puppy with nothing in their history is in the best possible position from an insurance point of view. That position gets more complicated with every vet visit.
"An eight week old puppy with nothing in their history is in the best possible position from an insurance point of view."
It's also why switching insurers isn't always straightforward. Your current insurer may continue to cover conditions that developed while you were with them, as long as you keep renewing. A new insurer will look at the same conditions and exclude them as pre-existing. The continuity of cover you've built up doesn't transfer.
Some conditions that fully resolve can eventually be covered again after a period with no symptoms, often 12 to 24 months depending on the insurer and the condition. Its worth asking about this specifically rather than assuming the answer either way.