Horse News & Views - September 2006

Ministry of Agriculture, Food and Rural Affairs

Ontario Association of Equine Practitioners

• Respiratory infections often affect horses during or after attending an equine event. Horses come to these events from a wide geographic area and differ greatly in their previous exposure to, and protection from, the respiratory viruses. Many factors determine whether a disease outbreak occurs or whether only a few horses get sick. They include: the presence or absence of a highly pathogenic agent; its ability to spread, directly or indirectly, to and between horses; the ambient temperature and humidity; the presence or absence of a properly functioning ventilation system; and a horse's susceptibility, based on previous exposure and vaccination status.

  The respiratory viruses can't be distinguished by the presenting clinical signs of the infected horse. Laboratory testing is usually required. The respiratory viruses include: herpes virus (1 and 4), influenza (AE-1 and AE-2), equine rhinovirus (1 and 2), equine arteritis virus and equine adenovirus. The equine rhinoviruses are a separate group of viruses from the herpes viruses. Often the term 'rhino' is used to refer to 'Rhinopneumonitis,' the respiratory form of herpes virus. The relative prevalence and importance of each virus in causing respiratory disease in the horse population varies from year to year and between geographic areas.

• The term "Coggins' test" may have to be replaced. The test to diagnose equine infectious anemia (EIA) is named for its developer, Dr. Leroy Coggins. The Coggins' test is an agar-gel immunodiffusion test (AGID), which has been used for 36 years to identify horses infected with the EIA virus. The Canadian Food Inspection Agency (CFIA) has decided to replace the EIA-AGID (Coggins') test with the EIA-ELISA for diagnostic testing. The validity of both tests for export certification to the United States and Mexico remains unchanged (180 and 30 days respectively). For more information on EIA and/or the CFIA's control program, contact the CFIA's local office or refer to their website.
  
  

Related Link

• Canadian Food Inspection Agency - Equine Infectious Anemia
  
  

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