Bacterial complications of traumatisms caused by animals are very frequent if no proper therapy is applied. Germs detected in the wounds caused by cold-blood animals or by invertebrates are mostly represented by bacterias of telluric origin (responsible of gas gangrene, tetanus...) with the eventual worsening effect of venom. Germs detected in the wound caused by warm-blood animals have their origin in the dental commensal flora in which anaerobic germs prevail. Pasteurellosises are specially feared after animal bites but human bites too must not be neglected. Therapy first target must be the elimination of anaerobic conditions and antibiotherapy is required for every deep injury.