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    Equine Herpes Virus Outbreak in 2021

    This new year commenced with different energy and excitement in the equestrian competition industry. After being for several months almost all shows and competition arenas in lockdown worldwide, the equestrian world opened its doors early this year starting with the new reality and by following the established safety rules to prevent Covid-19 increasing cases.

    However, this great news lasts very little when an outbreak of Equine Herpes Virus (EVH-1- Neurological form ) hit the showgrounds of Valencia, Spain, in February 2021. Since the end of January, many international showjumping competitions where hold in these arenas non-stop causing the spread of the virus among these horses and reaching other countries in mainland Europe, such as Belgium, Denmark, France, Germany, Italy, Slovakia, Sweden, and Switzerland; after some of the horses in the venue returned home before the outbreak was notified by the national federation.


    ‘‘The most serious EVH-1 outbreak in Europe for decades’’ is how the International Equestrian Federation (FEI) and other organizations have classified the severity of this situation. Several veterinarians and health facilities were put in place to face the immense amount of equines affected by the disease and leaving a dark number of 18 dead horses.


    Getting to know...What is Equine Herpes Virus?

    Equine Herpes Virus is a highly contagious worldwide disease that only affects horses. Through investigation and clinical studies, there have been found nine strains of EHV, being Equine Herpes Virus- 1 (EHV-1) and Equine Herpes Virus-4 (EHV-4) the most seen. EVH-1 may cause abortion, respiratory and neurologic disease, while EHV-4 mainly causes respiratory disease and rarely the other two. In pregnant mares, there is a high risk that the virus is transmitted to their foals causing fatal outcomes.



    Once there is an infection, the incubation period can vary from horse to horse. It can be as short as 24 hours to over a week, being 4-6 days the average statistic.

    EHV-1 is usually presented by a biphasic (two-phases) fevers peak, one in the first two days and the second in a week (day 6-7). When the respiratory system is being affected, the horse may present:

    Nasal and ocular discharge, Enlargement of the submandibular lymph nodes (jaw area). Coughing Lack of appetite Fever between 38,8 and 41,6 Celsius degrees. Depression

    If the affection is neurological, Equine herpesvirus myeloencephalopathy (EHM), the warning symptoms are mild, being mainly respiratory signs and fever. It progresses rapidly reaching the peak point within 24-48 hours. Some clinical signs are the following:

    Incoordination Hind limb weakness Loss of tail tone Lethargy Urine dribbling Head tilt Leaning against a fence or wall to maintain balance Inability to rise

    How is EHV transmitted? 

    Equine Herpes Virus is a highly contagious airborne disease that can be transmitted directly and indirectly through horses. Horse to horse transmission can occur up to 5 meters distance through nasal discharge or air droplets cough up in an enclosure space. Likewise, infected horses can return home and transfer the disease to their venue.

    Indirectly, yard and horse equipment, clothing, and close spaces in which an infected horse is been, such as trailers and lorries, are potential vias of EHV transmission.

    How is EHV tested?

    If there are any signs of a horse been infected by EHV or the horse already displays symptoms, a professional veterinarian will determine a diagnosis by examination and by analyzing samples of mucosal swabs from the infected horse and co-living equines. Blood tests for the detection of antibody levels may also be carried out if necessary.

    Asymptomatic and recovered horses from EHV-1 can still be carriers, and transmit the virus to another horse. Veterinarians advise testing all the yard horses or those who share common facilities for detection of EHV-1.

    How is EHV treated?

    The use of non-steroidal anti-inflammatory drugs might be beneficial to mitigate inflammation and pain and reduce fever. Alongside some nutritional support could help in the case of horses presenting loss of appetite. Horses must be isolated in strict quarantine for 30 days as a minimum and monitored for symptom control.

    Horses with neurological symptoms should be kept from lying down as much as possible, however, those that cannot stand usually face a poor prognosis of survival.

    Preventing measures of EHV 

    There two main methods to prevent an outbreak of Equine Herpes Virus, vaccination and biosecurity protocols of protection.

    A vaccine against EHV-1 and EHV-4 is available under a specialist veterinarian licensed, horses owners can schedule their horses' vaccination throughout the year depending on the risk, i.e prevent abortion of a foaling mare, competitions away from home, etc; and/ or as a protection barrier at home. Unfortunately, there is no vaccine against the neurological form of EHV-1, EHM.

    In terms of Biosecurity protocols, preventing as much as possible direct or indirect contact with other horses no co-living in the same venue, or at international competitions, the exclusive use of grooming/ tack equipment on your horse, disinfect and clean areas where other horses might have been, such as trailers, shower areas, etc; not allowing your horse to drink from common drinkers or sharing food buckets, wash your hands between handling horses, are just a few measures to contain the disease from spreading.

    Author: Tamara R.

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