There is a bag at the place where the dog received the injection

It is generally normal for the dog to have a bag at the place where the injection was given. It may be because the dog has not absorbed the medicine temporarily, or the injection has not penetrated the skin or muscles. It is possible that there is a bag where the dog received the injection. If your dog’s bag is suppurating and the dog is accompanied by vomiting, loss of appetite, etc., you should go to the veterinarian immediately for treatment.