Some more ideas :
You could open a po box where you get your own private locker, and put a spare set of keys in there.
If your friend was willing, they could be the "co-ordinator".
They could explain to the police where the spare keys are, so the police don't have to use a forced entry.
But you should also be able to send a delayed email to the police, where you explain the same thing, plus give the contact details of your friend who will be helping to re-home your pets
Ideally you would do 2 delayed emails, with everything explained, and send to police and your friend.
Note : As always, please note that I strongly encourage you to seek help with whatever is troubling you. Things may seem hard, but with the right help they can improve. There are many sources of help if you look and reach out. Please seek assistance in any and every way possible. You alone must decide upon your actions and take full responsibility for them, and you should always favour seeking help and keeping out of harm's way.