Most rabies is transmitted from dogs to humans. For dog bites, whether rabies can be transmitted depends on the degree of exposure, bite or scratch. Only a small bite breaks the skin, which can lead to the transmission of rabies. Because on the grading of rabies exposure, only broken skin, without bleeding, is a secondary exposure. This type of exposure should also be treated with the appropriate precautions, namely rabies vaccination. Because this level of exposure is not too high, there is no need to inject rabies serum. When there is bleeding, this is a higher level of exposure, when the likelihood of transmission increases, so rabies serum needs to be added to the rabies vaccine. However, when there is no bleeding, only broken skin, there is also the possibility of rabies transmission, and because it is less likely to be transmitted, rabies serum is not needed.