Hello Yellowshoes.
First, let me say I appreciate that you cared enough about those poor dogs to ask at the Albergue for help and to post a help request here. Too many people who don't care at all.
Sadly I can't be of much help
Probably would have been easier for you to do something for them while you were still there. Don't want to criticise you, but walking away seldom works in such cases. Nobody feels responsible, everyone just waits for someone else to do it, and in the end, nobody does.
But well, now concentrate on what still can be done.
Is there really nobody who knows the region better who can give some advice here?
I did a google search and found out there's a no kill dog shelter in Ourense, but that's almost 100km away from Samos. I doubt they'll drive out there but maybe they can give you the number of another shelter that's closer? They have an emergency number on their homepage, I don't know if I'm allowed to post a link here, but if you google for „Progape Ourense emergencia“ you will find it. You can ask another pilgrim or a hospitalero to translate or make the call for you.
I hope you find a way to get the dogs help. Maggots kill within a few days, what a horrible way to die