I've found everyone's remarks both fascinating and alarming. I re-call that when I had a Pet Shop, one of my Customers decided that the monthly contribution they would make for Pet Insurance, they would pay into a special bank account. If Vet's fees had to be paid out, they came out of the special bank account (interest earning of course).
In the early days of the dog's life, more went into the account than came out, so that funds were quite substantial by the time the pet needed treatment at an older age.
Personally, I thought that they were taking a considerable risk in the event that the cost of treatment was very high. However, they had been doing it for several pets over many years and it worked for them.
I'm not quite sure how they covered the eventuality of third party claims, unless they somehow covered it on their Home Insurance.
Thought you might find this interesting.