This is HEARTBREAKING! That picture of Max makes me want to cry for real. (((HUGS))) to you. The vet should cover the costs of all this at this point. Why did the vet who did the neuter not do bloodwork first?? The vet should be responsible for the health and well being of your pup BEFORE ever putting him under like that.
Man, my heart is just broken.
I pray Max makes a recovery, I soooo pray for that. My heart is with you, my thoughts and prayers too.