The African Horse Sickness virus has been causing havoc amongst the equine population in Thailand, with hundreds of horses having died of the disease and movement restrictions on all equids in place in some areas of the country. Horses have no natural immunity to the virus, so the majority of exposed horses will become ill. The virus causes several different forms of disease: a respiratory form with fever, breathing difficulties and often a rapid progression to death; a cardiac form with fever, swelling of the eyes, gums, cheeks and neck with occasional colic signs; a mixed form; and a ‘horse sickness fever’ which involves fever, a reduced appetite, depression and often a recovery from the disease.

The virus is spread by biting midges, and sometimes dogs become infected by eating infected horse meat. Unfortunately, there is no specific treatment for this virus, other than supportive treatment of infected horses. African Horse Sickness is endemic (infection is regularly present) within central Africa, from where it regularly spreads to other areas of the continent. Prevention involves a vaccine (only available in some countries), and fly avoidance.