Mediterranean Equestrian Tour Cancelled due to outbreak of EHV-1 virus

Mediterranean Equestrian Tour (Spring MET II, 7 to 26 February) in Oliva Nova, Spain, has seen the second half of the event cancelled after four horses returned positive tests for Equine Herpes Virus – EHV-1.  

MET representatives released a statement on 22nd February 2023 saying that all four horses are showing signs of fever, however, none show any signs of any neurological disease. On 10th February, 10 horses who were all stabled together in one tent were placed into isolation after six showed signs of fever. All were swabbed with four returning positive results, two inconclusive and the remaining four negative. Another horse has tested positive in Lier Belgium. The Valencia Veterinary Department has concluded that all 82 horses stabled in the same tent as the four who tested positive must remain at the venue for at least a week and will be subject to further testing. Altogether, a total of 989 horses were competing at the Spring Met II in Valencia.

Once the positive tested horses have been subjected to a schedule of re-tests and are confirmed negative, they must return home to their own stables and will be blocked in the FEI database as per the FEI rules. Horses that have not been stabled in the same tent are free to leave immediately subject to the same measures as the positive tested animals i.e. returning to their own homes and blocked in the FEI database. 

EHV1 can manifest in four ways: neurological form, respiratory disease, abortion and neonatal death. EHM is most commonly due to mutant or neuropathogenic strains of EHV-1. The most typical causes for horses to contract this virus include Equine Influenza Virus (EIV) – also known as Rhino and Streptococcus equi subspecies equi (S. equi) – better known as strangles. 

Lessons Learned

In 2021 there was a large outbreak of EHV-1 throughout Europe, which coincidently saw the outbreak begin in Valencia, which sadly concluded in the death of 18 horses in mainland Europe. This outbreak led to a six-week shutdown of all international events from 1st March 21 to 11th  April 21 to help minimise the spread of the virus. The FEI completed a comprehensive study which revealed human error, lack of rule compliance and systemic failures which enabled a rapid spread to a effect great many horses.

Resulting from its investigation, the FEI found that there were several febrile horses at the venue as early as 14th February 2021. It was not until 20th February that this information was passed to the FEI Veterinary department. There were found to be four horses at the venue testing positive for fever on 17th February reported by the FEI veterinary team leader, but the FEI was unaware of these until the receipt of this information in March 2021. By this time, two further horses were febrile, confirmed on 19th February 2021. 

The FEI ordered the cancellation of this event; by Sunday 21st February there were around 45 febrile horses but the competitions surged ahead, only halting when the FEI Veterinary Director warned that the FEI could take immediate disciplinary action unless the event was immediately cancelled. The horses then left the venue in an uncontrolled manner, without the appropriate health papers, further promoting the spread of the virus.

Furthermore, the report states that there were only 2 veterinarians available between 20th and 26th February, left to provide health care to the now many very sick horses. The FEI investigation revealed a number of basic missed opportunities to protect the horses including lack of examination on arrival, basic hygiene protocols not being adhered to, lack of biosecurity contingency plan, and a lack of temperature monitoring.

The FEI has now reinforced its rules as well as improving the education of organising committees, officials and athletes. 

It does appear that lessons have been learned since the 2021 event in Valencia and steps to try to control this recent outbreak have been taken to accelerate the reduction of the virus spread. 

EHV and your horse

If you suspect your horse, or other horses in close proximity to it show symptoms of the virus you must isolate your horse and call the vet immediately. In most cases, horses make a good recovery from those who develop respiratory disease. However, the outlook is not so positive for animals with neurological disease which can be more variable with hard to predict outcomes. 

Your vet will take a nasopharyngeal swab and potentially a blood sample from your horse. All horses that have had direct, or indirect contact with the infected horse should be closely monitored and their temperatures taken twice a day and isolation procedures put in place.   

Once a horse is infected with EHV it can remain present for life. Therefore, almost all horses are life long carriers of EHV. 

Carrier horses show no clinical signs, but the infection remains in their body. The virus can be re-activated at any time and spread to other horses.

Re-activation often occurs as a result of stressful conditions or a period of fatigue, for example:

• During transport
• Strenuous exercise
• Mixing at equine events

Good biosecurity measures, particularly when dealing with potentially infected horses, is key to the control of the disease. Reducing the potential stresses that set off disease spread is important, as well as reducing issues such as overcrowding. Horses that are sick must be immediately isolated; discuss EHV with your vet and within your yard – a group approach is the best way to manage the threat of this common disease, being vigilant around yard, stable, equipment and personal hygiene really does help to minimise the risks of the spread of this potentially fatal disease.

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