A highly contagious viral disease primarily affecting the respiratory system. There are many different subtypes of virus, and not only horses, but also humans, pigs and birds are susceptible to the disease. The infection is transmitted through the air and through contact with mucous membranes of the nose and mouth. Typical clinical signs are fever, apathy, dry cough, reduced appetite and general discomfort. The disease can also lead to potentially fatal complications such as pneumonia, meningitis or cardiac myopathy. The disease can be prevented by vaccination, this is mandatory in most countries for horses that take part in official competitions. The date and type of vaccination is recorded in the horse's passport.