I have nothing all that helpful to offer, other than looking at your current potential resources/funders. For example, my parent's once (or rather three times, grrr) had a dog hit by a car and their Beagle needed jaw surgery and a pin placed in her shoulder. I don't think that my dad was aware of it at the time, but the brother of the owner of the company that he worked for had a HUGE soft spot for pets (and a lot of money to boot). He actually had set up a pet foundation for vet bills, but was very low-key about it. When my dad talked about his problems at work, he discovered the foundation, applied, and the vet bills were covered.
Good luck in finding funding, and I hope that Mervin has a swift recovery!