African Horse Sickness (AHS) is a highly infectious disease that is primarily found in Africa and the Middle East. It is spread by insects (Culicoides midge), and causes respiratory and cardiovascular failure.

One of the more notable signs is frothing nasal discharge and coughing; however, swelling of the head and neck (edema) are also common. The mortality rate in horses depends on the form of disease contracted, but it is generally very high. There are several strains (serotypes) of this virus.

AHS is a reportable disease, meaning that if a horse has or is suspected of having this disease, vets are required to report it to agricultural authorities (usually the State Veterinarian). These authorities may investigate the case as part of a larger effort to monitor equine health and coordinate with other states and the USDA APHIS in preventing the spread of illness or disease on a national and international level.