How do vaccines work for horses?

Vaccines work by stimulating the horse's immune system to produce antibodies, which are proteins that help recognize and neutralize specific pathogens such as viruses and bacteria. When a vaccine is administered, it usually contains a weakened or inactivated form of the pathogen, or components of it, that can safely trigger an immune response without causing disease. This process allows the horse's body to "learn" how to identify and combat the actual pathogen if it ever encounters it in the future.

The production of antibodies is crucial because it prepares the horse's immune system to respond quickly and effectively to future infections by the same pathogen. This immunological memory means that the horse is less likely to become ill if it is exposed to the disease later on. Such vaccination is a proactive measure in maintaining equine health and preventing outbreaks of diseases.

In contrast to this, other options do not accurately represent how vaccines function. For example, vaccines do not provide instant immunity; it usually takes time for the body to produce sufficient antibodies after vaccination. They also do not kill pathogens directly; instead, they prepare the immune system to fight off infections. Lastly, while some vaccines may help prevent certain external parasites, vaccines mainly target internal pathogens rather than a broad range of parasites.