Our annual AHS horse massacre

20th January 2023
Beryl Shuttleworth
No Responses

When I post about African horse sickness (AHS), I always wonder what our overseas readers think. I wonder if they understand how utterly devastating the annual countdown of deaths is. Perhaps they think we are making too much of a fuss. This article is for non- South African horse people, so that you can understand.

Swollen face (CABI)

Firstly, here are some facts to fill you in:   AHS is a viral disease that primarily affects horses, mules, and donkeys. It is caused by a virus of the genus Orbivirus, which is spread by the biting midge Culicoides imicola. The disease is often fatal, with death occurring within a few days of the onset of clinical signs. The disease is endemic in sub-Saharan Africa and is considered one of the most important viral diseases of equidae in the region. There is no specific treatment for AHS, and control measures include vaccination and vector control.

We have a vaccine, consisting of two injections three weeks apart. We are required by law to vaccinate annually between June and October (because this is when there are fewest vectors). The vaccine is a modified live vaccine. We have an AHS free zone in the Western Cape, which is really important for all sorts of reasons.

I’m not going to go into it now, but as you can imagine, “shit happens”. We have people who are anti-vaxxers on their horse’s behalf. We have a large part of our population that can’t afford to vaccinate. We have people who don’t vaccinate in the window of few vectors because of their completion schedule. And then the virus is way more efficient at mutating than the vaccine manufacturer is at keeping up with mutations.

Foaming nostrils (from CABI)

As a result of these and other factors, every year, usually around February and March, my Facebook timeline feels like an mass equine massacre. It is heartbreaking. It is an ugly disease – images of bleeding eyes and foaming nostrils are common.

The AHS trusts describes the symptoms thus:

“The disease manifests in three ways, namely the lung form, the heart form and the mixed form. The lung (dunkop) form is characterised in the following manner:

  • very high fever (up to 41 degrees).
  • difficulty in breathing, with mouth open and head hanging down.
  • frothy discharge may pour from the nose.
  • sudden onset of death.
  • very high death rate (90%).

The heart (dikkop) form is characterised in the following manner:

  • fever, followed by swelling of the head and eyes.
  • in severe cases, the entire head swells (“dikkop”).
  • loss of ability to swallow and possible colic symptoms may occur.
  • terminal signs include bleeding (of pinpoint size) in the membranes of the mouth and eyes.
  • slower onset of death, occurring 4 to 8 days after the fever has started.
  • Lower death rate (50%).
Swollen eyes (from MSD)

The mixed form is characterised by symptoms of both the dunkop and dikkop forms of the disease.”

Horse owners try all sorts of preventative measures. Fans in stables or burning drums in the yard are ways to discourage midges (or miggies as we call them). Sweet itch rugs are commonplace in paddocks. Cannabis has long been used as an alternative treatment, even when it was illegal. We watch the hollows above the eyes like hawks – its a problem if they start to fill.

There is even a name for this time. We call it AHS season. And there is no guarantee that my horse (despite being vaccinated and well looked after) will not be a victim.  So please keep us South African horse people in your thoughts – we are not okay.

Leave a Reply

Your email address will not be published. Required fields are marked *