EHV-1 Outbreak: All You Need To Know

EHV-1 Outbreak: All Horse Owners Need To Know

In light of the recent EHV-1 outbreak, horse owners need to vigilant and educated on the virus and how it manage cases and suspected cases of infection. With international equestrian centres across the country already issuing restrictions regarding horses that may have been exposed to EHV-1, all horse owners need to be alert to identification procedure and management protocols.

What Is EHV-1?

EHV-1, otherwise known as equine herpes virus, is one of nine equine herpes virus strains that have been identified to date. The equine herpes viruses are an endemic in the UK, meaning that cases are identified regularly in UK, however some are more serious than others.

EHV-1 is one of the more common strains of the disease and can be fatal. Manifesting it’s self in different ways, the virus can affect neurological function, respiratory, reproduction and the health of foetuses and new born foals. Older animals are considered at increased risk for the development of neurological symptoms during an EHV outbreak.

Once a horse is infected, it can harbour the virus throughout its life and potentially shed the disease to other horses without showing any outward signs. Re-infection and shedding from infected horses tends to happen when they are stressed – typically moving yards or in hard work.

The disease is currently not notifiable, therefore owners of horse’s suffering from the virus do not have to inform the state. This can make the disease hard to control and manage, so reliance on owner honesty is crucial to reduce the spread.

How is EHV-1 Spread?

EHV-1 is highly contagious and can be spread by through direct and indirect contact, as well as through the air.

Direct contact with horses carrying the disease, or contact with any bodily secretions can cause the infection and spread of EHV-1. Additionally, indirect contact with infected horses can cause the spread of the disease. Indirect contact can be caused by the use of equipment contaminated by the virus, including but not exclusive to objects such as;

• Human contaminated hands or clothing
• Contaminated equipment and tack
• Contaminated trailers used for transporting horses
• Contaminated wipe rags or other grooming equipment
• Contaminated feed and water buckets

The air around the horse that is shedding the virus can also be contaminated with infectious virus. Although it is known that the virus can be airborne, it is difficult to establish the distance the virus can spread in this manner under typical horse management and environmental conditions.

Signs, Symptoms and Treatment

Horse may not show signs of infection straight away, with an average incubation period of 1-6 days before symptoms are visible. However, the onset of symptoms after infection could be longer in some cases.

Clinical signs include;

• High temperature
• Coughing
• Nasal discharge
• Lethargy
• Loss of appetite

Severely affected animals can display neurological symptoms, and pregnant mares can also suddenly and unexpectantly miscarry their unborn foal.

As a virus, there is no specific anti-viral drug or treatment, much like there isn’t for human virus such as chickenpox or shingles. Similarly, EHV viruses can lie dormant after the patient recovers, and reoccur at a later date, normally when the horse is under stress -this is called a latent infection.

Controlling The Spread of EHV-1

It is in the equestrian community’s best interest to reduce and prevent the spread of EHV-1, due to the massive welfare, financial and emotional implications attached to the disease. Therefore, use of best-practice, bio-secure yard measures when dealing with an outbreak always recommended. These measures also apply to those horses who have recently come into contact with the disease or a suspected case, through direct or indirect contact.

The virus normally survives for up to 7 days outside of the horse’s body, however under perfect environmental condition, it has been known to survive for up to a month. Therefore, disinfecting equipment used in or around horses with EHV-1 is required for a period surrounding diagnosis or suspicions. Normal disinfectants are known to kill this strain of the disease, and it is advised to disinfect equipment every time after use with horse’s suffering the disease, or suspected to be suffering. Equipment should not be shared amongst other horses.

For those suspected to of come into contact with EHV-1, directly or indirectly, the Animal Health Trust (AHT) advise a period of isolation.

Dr Richard Newton, Director of Epidemiology and Disease Surveillance at the AHT, stated;

“We recommend that such horses should be placed in isolation for 14 days, avoid direct and indirect contact with other horses and undergo daily clinical monitoring, including twice-daily rectal temperature recording.”

An entire yard isolation is essential when there is a cases of the disease present. This means no hacking out or travelling, in an attempt to reduce the spread. Veterinary advice should then be sought regarding release of horses from isolation, following results from necessary sampling and laboratory tests.