Herpes viruses endanger horses: doctors fear bottlenecks in vaccines

University confirms herpes virus infection in several horses
Bad news for horse owners: In a horse stock in the Limburg-Weilburg district, several horses are likely to have a herpes virus infection. As reported by the Justus-Liebig University of Gießen, it is an equine herpes virus (EHV-1), which often leads to death in horses and can spread epidemically. An extensive vaccination could help here - but the approved vaccines are currently not available in Germany. To prevent spreading, several riding tournaments have now been canceled.

Once infected, the virus still carries the virus latently
In Beselich (Limburg-Weilburg district, Hesse), several horses have probably developed an equine herpesvirus-1 (EHV-1) infection. This is often fatal in horses and can be epidemic - accordingly, there is great concern among horse owners in the region. The virus does not cause communicable diseases in humans, but contact with infected animals can lead to infection of previously healthy horses. The infection caused by EHV-1, which is widespread among horses, is partly without symptoms. "Once infected, the virus carries the virus virtually invisibly ('latent'), and there is no way to get these horses completely EHV-1 free again," said Prof. Fey, according to the Gießen University.

Longer lying down may require the animals to be put to sleep
The tricky thing: the herpes virus can also lead to serious illnesses. A fever often occurs at the beginning, often in combination with nasal discharge and cough in young horses. In severe cases, coordination disorders (ataxia) occur after the first phase of fever, which can be accompanied by difficulty in urinating and droppings. The disorders usually begin in the hindquarters first, but then also appear in the forelimbs. In the worst case, the horse can no longer stand up ("lying down"). This neurological form of EHV-1 often affects several horses in the herd. If the horses are in the same position for longer, there is a risk of serious damage to health, which is why the animals usually have to be put to sleep, the university reports.

The causes of the infection cannot be treated
Like many other viral diseases, a herpes virus 1 infection cannot be treated causally. Accordingly, the therapy aims to alleviate the respective symptoms. This is e.g. circulatory infusions and antibiotics are available to treat secondary infections. It is also important that the animals concerned are dewormed, housed as little germs and dust as possible and separated from the other animals in order to prevent them from spreading. Since infected horses can excrete the virus before symptoms appear, even horses that appear healthy from affected stables may no longer be transported to other stables at the first suspicion.

Vaccination can reduce the viral load in the herd
Vaccination can provide protection, especially if all horses in a herd are registered. Due to the large number of animals already infected, this cannot reliably protect against the infection itself, but it significantly reduces both the severity of the disease and the virus excretion. A comprehensive vaccination could consequently reduce the viral load in the population, reports the university.

However, vaccines approved in Germany are currently not available. As the "Wiesbadener Kurier" reports, the animal health division of the pharmaceutical company Sanofi ("Merial") recently switched to Boehringer Ingelheim. This opened a "European Research Center for Animal Vaccines" in Hanover in 2012 to develop innovative vaccines - but only for farm animals, Matthias Kagerbauer von Boeringer told the newspaper.

Vaccine bottleneck has existed for a year and a half
"The pharmaceutical industry has to accept the accusation that it has not done enough for animal health," said Wiesbaden veterinarian Stephen Eversfield. According to the veterinarian, there has been a bottleneck in the vaccines for a year and a half - he himself is now getting his herpes vaccine from the Czech Republic with an exemption. According to Eversfield, an epidemic like the one currently in the Limburg-Weilburg district is rare, but certainly possible in stables with unvaccinated horses. Therefore, in his opinion, the herpes vaccination for tournament horses should be compulsory, as should the semi-annual influenza vaccination. However, emergency vaccination with imported substances is only conditionally recommended. Because in the four weeks between the two vaccinations for the basic vaccination, the animals can still become infected. In the case of horses that have already been vaccinated, it may make sense to have them vaccinated. (No)

Author and source information

Video: An overview of Herpes Simplex Encephalitis (January 2022).