What is Equine Herpes Virus?

There are two types of herpesvirus found in SA, namely EHV-1 and EHV-4.

The respiratory tract is a common site for replication for both viruses, and therefore nose to nose contact can lead to transmission from infected to susceptible horses. Horses can become lifelong carriers with triggers leading to “activation” of the virus and subsequent shedding. Stressful conditions can lead to activation. (Similar to having a cold sore as a human)

Clinical Signs

EHV-1 is a primary respiratory disease, which can lead to late term abortions, foal death, neurological symptoms.

The respiratory symptoms are normally seen in all cases; the neurological symptoms (hindlegs are wobbly, can even lead to paralysis, urinary incontinence), are normally preceded by the viraemia, which means that at the time of the symptoms you will not find virus in the blood.

EHV-4 is normally restricted to the respiratory tract. Fever, coughing, nasal and ocular discharge.

Diagnosis

Contact the Equine Research Centre to arrange testing by PCR. The best sample is a dry nasal swab, and this should be accompanied by an EDTA (purple top) blood sample. In the case of abortions, foetal lung samples and placental tissue (FRESH and never in formalin) as well as a vaginal swab from the mare are the specimens required for testing.

Treatment and Control

Symptomatic treatment is the mainstay. The infection is normally mild and self-limiting.

Prevention of spread is critical and direct contact is the main form of spread.

Vaccination options are available. Contact your vet for more information.

This disease is considered endemic in RSA. As EHV is not a controlled disease, no specific state veterinary control measures are in place for EHV.

Responsible horse ownership must be relied on. Basic hygiene principals at shows and within stable yards are paramount to successful control. Direct contact with horses from other yards should be avoided, as well as use of shared water buckets etc. In the face of an outbreak, horses should be separated into groups or if possible, housed individually, until the outbreak is under control. This applies especially to pregnant mares, as an aborted foetus is a large source of virus for other mares within the same paddock.

Contact:

Dr Camilla Weyer for sample organization (Best done in consultation with your vet)

076 152 2782