Pets are companions who you steward because you're the name on the lease and the one with the bank account. Like all living things, they're usually healthy without intervention as long as their basic needs are met. If you can fulfill that stewardship 100% of the time for 5 or 10 or 20 years, but then can't pull things together in some exceptional case at the end, that's not a failing. That's just one of those sad things that happens in life.