Sensible biosecurity measures based upon a specific risk assessment performed in consultation with the attending veterinary surgeon and, where necessary, others with expert knowledge of equine contagious disease control, are essential to minimize the risk of introduction of infected horses and aerosol or mechanical transfer of infective virus to non-infected horses.
Effective quarantine for new horse arrivals is of major preventive importance. It is clear that during the 2018/2019 EI outbreaks reported throughout Europe, including UK, many reported cases of EI followed the introduction of new horses into stables, some from abroad, some from sales and others from stables elsewhere in UK. Ideally, in-coming horses should be held at a separate location, with dedicated staff, for 10-21 days, during which time they are monitored daily for any clinical signs of all infectious diseases (e.g. raised rectal temperature, nasal discharge, coughing, diarrhoea, skin lesions, inappetence, depression). If these occur, they can be investigated, treated, recovered and proven to be of no further risk of transmission, in isolation, before they are introduced to the main stables. If multiple horses are involved, the whole batch is quarantined and monitored in this manner before being released ‘into the herd’. For stud farms without separate facilities, an appropriately separated yard or a section of stables should be designated as a quarantine area, under the supervision of the attending veterinary surgeon, with designated staff with appropriate protective clothing and work practices.
If contagious disease is diagnosed in quarantine, the stables and paddocks become an isolation unit (see Appendix 6). For stud farms with only a few horses, introduction of EI means that the whole unit needs to be ‘isolated’ until the infection has taken its course and the horses are recovered and confirmed to be free of disease and no longer constitute a risk of spread to other horses.
On stud farms, pregnant mares, mares with foals at foot and non-pregnant mares should be managed separately, with separate staff and there should be designated quarantine facilities, staff and protocols for incoming horses and for when contagious infections occur, to avoid their spread.
Vaccination and biosecurity measures may help to avoid an epidemic developing and spreading. However, EI infected horses can shed infectious virus before they show clinical signs so significant spread may occur before the first case is diagnosed. Horses may show minimal clinical signs and therefore specific testing (see diagnosis) should be performed without delay, if EI is considered a risk, irrespective of clinical signs.