So sorry to hear of Cricketts issues that is tragic. Here is something you can try...you can to to
Fundraising, Group Purchases ? Fundable and make a plea for a financial amount for donations for his vet care.
You can also go on the internet and find companies that will help you do a fundraiser to raise funds you might be surprized what you can come up with.
I do feel your neighbor has some responsibility even if is is 50% of the bills.
Rizzo's mom forever