Equine influenza virus is a highly contagious respiratory virus that affects horses. It is caused by the influenza A virus and can spread rapidly among equine populations, especially in crowded environments like stables and racetracks. Symptoms include coughing, nasal discharge, fever, and lethargy. Vaccination is the primary method of prevention, helping to reduce the severity and spread of the disease. Infected horses typically recover within a few weeks, but complications can arise, particularly in young or elderly animals. Proper hygiene and biosecurity measures are essential to control outbreaks of equine influenza.