The anti-venom can be generated by injecting a horse with a dilute preparation of snake venom; the horse then makes antibodies to the venom that can be harvested. Use of horses is preferable to injecting humans with any preparation of snake venom. A person may develop an immune response to antigens present in the horse serum. If exposed to it again, the person may launch an immune response against the serum, resulting in serum sickness.