What is African Horse Sickness? General, Horse / Thursday, July 4th, 2019 Frequently proving fatal, African Horse Sickness (AHS) is highly infectious viral disease. Fortunately, there have been no reported cases in the UK. It has never really been considered a threat to horses in this country – until now. The effects of climate change and the growing number of international equine movements have combined to raise the possibility that AHS could reach our shores. The risk is not considered to be high at present. But the outbreak of Bluetongue that occurred in 2007 has shown that it is possible for such diseases to arrive here. Outbreaks have previously been discovered in Spain and Portugal. The Bluetongue virus is similar to the AHS virus. It may be possible for AHS to occur in Britain and so it remains important to be aware of the disease. Should it be found in the UK, it is vital that it is identified quickly to prevent it spreading. AHS is a notifiable disease. This means that if you suspect a horse may have it, you must immediately notify the duty vet in your local Animal Health Veterinary Laboratories Agency (AHVLA) office. How is African Horse Sickness spread? The AHS virus is carried and transmitted by a species of midge from the Culicoides family. AHS is transmitted to a horse when an infected female midge bites it. The disease cannot be transmitted directly from one horse to another. However, if an infected horse is kept in close proximity to other animals, there is an elevated risk of an infected midge biting a healthy horse. Variants of African Horse Sickness There are three types of AHS; the lung form which is an acute illness, the heart form and the mixed form. Symptoms of acute AHS • Rapid and significant rise in temperature (up to 41°C) • Severe difficulty in breathing with mouth open • Head hanging and nostrils dilated • High respiration rate (possibly over 50 breaths per minute) • Excess sweating • Abdominal heave lines due to forced expiration • Large amounts of frothy discharge from the nostrils • Redness of conjunctivae • Coughing Sadly, 90 per cent of infected horses will die within one week. Once a horse exhibits respiratory distress, death may occur within 30 minutes. Symptoms of cardiac AHS • High temperature (up to 41°C) • Swelling of eyelids, facial tissues, neck and shoulders • Loss of ability to swallow • Respiratory distress • Colic symptoms • Bleeding in the membranes of the mouth and eyes (these are terminal signs) The mortality rate of the cardiac form of AHS is 50 per cent. Once an infected horse shows signs of fever, death usually occurs between four and eight days later. Symptoms of mixed AHS If a horse is suffering from the mixed form of AHS, it will exhibit symptoms of both acute and cardiac AHS. These usually begin with mild respiratory issues which will be followed by the swellings seen in the cardiac form of the disease. The mortality rate of horses with the mixed form of AHS is 70 per cent. African Horse Sickness is a threat to horses in the UK. Infected midges could be transported here accidentally on planes or the midges could be carried here via abnormal winds. Remain vigilante and seek advice if you see worrying symptoms.