I put away the $25 per cat in an account every month. I figure, no one offers something like this unless THEY are making money, right? So I might as well hang onto that money, but make sure it's around, just in case. Peak times for claims are during the cat's first year (vaccinations), and after the 6th year. Between years 1 and 6, claims are almost nil.
Also, my cats could develop some horrible, life-altering illness, but I highly doubt I would find myself completely unable to pay it without having insurance. Savings should be sufficient. Why should my money go in their pocket, instead of my savings account?