It is not always necessary to give protein after a dog bite. The protein here refers to rabies immunoglobulin, which is an antibody injected directly into the body to fill the gap where the rabies vaccine has not yet produced antibodies, usually for about a week. If you are judged to have a secondary exposure, you do not need to inject the protein again. If the wound is judged to be a tertiary exposure, that is, if the wound is not only broken, but also bleeding, or even deep, it will take about a week for the vaccine to take effect, so rabies immunoglobulin is needed in advance for the body to produce antibodies. And the immunoglobulin also needs to be injected at the site of the wound, which can stop the rabies virus from entering the body from the wound. It is only injected at the time of tertiary exposure, but not if it is only judged to be secondary exposure.