"Holding Account
Read about how to use Vacation Points from a previously changed reservation.
Any time you change or cancel a Disney Vacation Club® Resort reservation 30 days to one day before your scheduled arrival date, the Vacation Points used for that reservation are put into a Holding Account."
I believe that you need to cancel 31 days out so they won't go into holding. That would mean the 28th is the very last day I believe. You could always call MS on to confirm....
Sorry about your pets, I have been in the same boat when my cat was 20 years old (RIP Tigger ). I would cancel too, you can't get timeback with your pets so enjoy everyday with them and reschedule your trip.