Quarantine is one of the oldest infectious disease control measures. Formal use of quarantine dates back at least to the 14th century in Italy, where city officials banished people infected or exposed to people with plague (“black death”) for 30 days. This was termed “trentino.” Later extension of this to 40 days led to the term “quarantino,” which evolved into our current term, “quarantine.”

The first use of quarantine in horses is unknown, but historically this practice has been used to control various diseases, with variable success. Quarantine is still used, including quarantine of newly arrived horses on farms, of horses upon arrival to certain countries, and isolation of horses known or suspected to be carrying certain infectious diseases.

Specific quarantine practices vary with the infectious agent(s) of concern, but they typically involve physical separation of quarantined horse from other horses, restriction of movement on and off the farm, and specific protocols for handling horses. These are designed to detect early signs of disease in quarantined horses and prevent transmission of infection, should horses be carrying infectious agents. Quarantine can be a highly effective practice when developed and used properly.

One of the major problems with quarantine is poor compliance. This was clearly demonstrated by the recent situation in which three horses were broken out of piroplasmosis quarantine