Horse serum is used in the creation of vaccinations; horses are subjected to harmful diseases for the sole purpose of creating antibodies against these diseases that can be used in human vaccinations. Diphtheria, tetanus and scarlet fever all have vaccines that utilize the antibodies that are present in horse serum.
Horse serum is generally produced in the United States where it comes from donor horses that have been raised in the U.S. It is tested for bacteria and is sterilized to ensure that it does not have any fungi or diseases. Horse serum can be used for many different issues including traditional diseases, snakebites and even some protection against infections. In the U.S., there are many people who are allergic to horse serum. It is important that people be tested for an allergy of the serum before they are given an injection. An allergy to the serum can cause a rash, a fever and even sores around the site of the injection. A skin test will generally be able to notify doctors that a person is allergic to the serum. There are alternate serums, like human serum, that can be used in people who have shown to have an allergy to horse serum.