Call animal control in the morning. Your neighbors dog will have to be quarantined because of the injuries for 10 days. Depending on the severity, that dog may be registered as a nuisance or, I’m going to guess from the picture, will have to be registered as a “dangerous” animal. your neighbor will have to go to court (animal control will file a report along with the PD). Once you have that together, file a claim with your homeowners insurance (if you have it). They will go after your neighbor (or insurance) for damages. This part is easier if you go through an attorney, honestly. (Source: just went through the same thing with my pup). Best of luck to you and I hope your pup makes a full recovery.