New dog: Excessive barking, aggression, and wonky ears.?

The friend can easily contact the vet where the dog has record and get a copy of the shots record for you. Hopefully your friend isn't lieing. I take my dog vaccination clinics. Its quicker, cheaper, i don't have to make appt. Can u take dog to your friends vet? Take the friend too. They would be familiar with pup already. Then you can change records of ownership. Since you have doubts of biting when you take to vet i would crate and muzzle it. You need to sign up for obedience training with him. He's evidently not been properly cared for and bonded with anyone and obedience training will help with many issues. Barking for absolutely no reason. No no barking. The yeast issue for ears get med from vet. I would tell vet you just got pup and don't know what social skills it has. Don't take chances that pup will bite. I know how nasty chis are. I was bitten by a friends chi 3x. They did nothing about it. Yet i have dobes go figure who has obedience training?