26/03/2025
Dear Horse Owners
We are having an extremely tough time with Viral Diseases at the moment in our area… African Horse Sickness (AHS), Eqiune Encephalosis Virus (EEV), West Nile Virus (WNV) and also with Biliary / Tick Bite Fever. We have many horses that are very sick, and we have had several that have died already. Whenever we have a very wet rainy season combined with periods of nice warm weather, there is a higher incidence of these diseases because there is a significant increase in the numbers of the insects that spread these diseases!
AHS (Dunkop & Dikkop) is transmitted by biting midges
EEV is transmitted by biting midges
WNV is transmitted by Mosquitoes
Biliary/Tick Bite Fever is transmitted by ticks
Please note that even horses that have been vaccinated against AHS, EEV & WNV can still get sick. The vaccine cannot give 100% immunity in all cases. In the case of Tick Bite Fever, the disease must be controlled by doing diligent tick control on the horses.
The main symptoms of AHS is
• Fever
• Loss of appetite
• Difficult breathing
• Swelling above the eyes
• In the case of DUNKOP AHS – sudden death is often seen without any other symptoms noticed before. There is often white foam coming from the dead horse’s nose and mouth.
The main Symptoms of EEV & West Nile Virus are:
• Fever
• Loss of Appetite
• Incoordination / staggering / loss of balance (Neurological Symptoms)
The main symptoms of Tick Bite Fever are:
• Fever
• Loss of Appetite
• Yellow Gums and eyes
Please note that an animal that suffers from these diseases may not always display all the symptoms.
Please note that these diseases are not contagious from one horse to another, but transmitted by the insects in the environment. This means that if one horse has the disease it is a clear sign that the insects in that specific area is infected with the disease and that the other horses in the area is thus also at high risk of contracting the disease. Also note that midges can fly and be blown by the wind 30km away!
Midges and Mosquitoes are most active where there is water / damp soil, and during dusk and dawn.
There are a few precautionary measures that we urge you to apply as far as you can to try an minimize contact with the insects that carry the diseases:
• Keep horses away from marshy, low-lying areas where there is water and damp soil
• If possible, stable horses at night – they should come in to stables well before sunset and only return to pasture well after sunrise
• Apply insect repellent (preferably a product that contains DEET) at least twice a day – concentrate on legs / belly / groin / face where there is the most contact with the insects.
• Use a fly sheet if possible – but still remember to apply insect repellent to the legs / belly / groin & face where the sheet does not protect the horse.
• Take your horse’s temperature twice a day – this allows you to now what your horse’s normal temperature range is and will let you notice immediately if there is a spike in temperature. Often you can see a raise in temperature even before you can see any other symptoms.
We urge you NOT TO TRAVEL at this time please! Travel always puts pressure on the horse’s immunity and traveling may expose your horse to areas where the insects may be infected.
Please have any suspect cases bled and tested in order for us so communicate the magnitude of the problem to the necessary regulatory bodies. National stats cannot be accurate if we do not test and report cases of the diseases and there is currently a very low reporting incidence because cases are not being tested and reported.
Let’s help each other keep our horses safe.
Dr Marleece Jordaan BVSc
DatariusVet Potchefstroom
Veterinary Clinic with a special interest in horses, Equine Sport Injury Rehabilitation and Equine Breeding
