IN THE spring of this year UK equestrianism was gripped by fears following outbreaks of a neurological form of equine herpes virus (EHV) infection in the South West, including at the Beaufort Hunt Stables in Badminton.

This led to cancellation of hunting and disruption of equestrian events, including withdrawal of several high profile horses from an international dressage competition at Addington in March and fears that Badminton Horse Trials would not go ahead in May.

The neurological form of EHV-1 is very rare but an unusual number of cases were recorded between November 2013 and May 2013, with outbreaks in Devon, Somerset and East Anglia, as at well as at two sites in Gloucestershire.

Two additional cases were reported - in Devon and Oxford - in July and August but none since. Does this mean the scare is over? Or should we remain vigilant?

First, it should be noted that EHV is in fact a common cause of respiratory illness in this country, with typically two outbreaks confirmed by the UK collating centre at the Animal Health Trust each month. In September, for instance, EHV was identified as the cause of respiratory disease in Oxford and Devon.

So, while hysteria earlier this year surrounded the neurologic from of disease, EHV has always presented a threat to horses attending and mixing at equestrian events. This is because the virus remains hidden but re-emerges to set up infection when horses are stressed by travelling and competition. In this respect it is very similar to the herpes virus that causes cold sores does in humans.

There are two strains of the virus - namely EHV-1 and EHV-4 - and both can also cause abortion and still-births as well as respiratory illness.

The respiratory form of EHV is associated with fever (rectal temperature 39-41oC, 102-106oC), coughing and nasal discharge. Neurological disease may also be preceded by these signs, followed by incoordination of the hind limbs, dribbling or retention of urine with colic signs, and recumbency.

Virus is usually spread by inhalation of droplets from infected horses coughing and snorting, who typically shed EHV for 7-10 days. This can, however, be longer in some cases.

The virus can also live in the environment for several weeks and there is potential for spread of infection via people, tack, and yard equipment. The incubation period from infection to development of signs is around 4-6 days.

If EHV is suspected, affected horses should be isolated and veterinary attention sought. If EHV is confirmed all horse movements should be stopped on and off the yard for 28 days and any pregnant mares placed in quarantine. The virus is easily killed by heat and disinfectants, so bedding should be destroyed, and stables, vehicles and equipment disinfected.

Risk of infection at events can be minimised by avoiding direct contact with other horses and not sharing feed/water buckets, tack and other equipment. It may also be wise to monitor the temperature of horses or ponies returning from competitions.

New entrants to a yard should be isolated for 3 weeks and their temperatures monitored on a daily basis. This is particularly important if they have come from an area affected by recent EHV outbreaks.

You may wish to consider vaccinating horses for EHV, which can protect against respiratory disease associated with both EHV-1 and EHV-4. Following an initial course of two injections four weeks apart, boosters are given every 6 months.

There is a strong case for vaccinating competition horses that frequently travel, especially to the south of England, because of stress associated with travel and the potential to mix with EHV-infected horses. The vaccine will also help prevent abortion due to EHV-1 and pregnant mares should be immunised at 5, 7 and 9 months of their pregnancy.

There has been debate as to whether the vaccine provides complete protection against neurological EHV. Evidence from historical outbreaks and some research suggests that it helps reduce the shedding of virus and thus the likelihood of infection.

Reasons behind the increase in neurological EHV earlier this year have not been determined and, with last recorded UK case of neurological EHV in August, it is perhaps too early to conclude that the scare is over.

Vigilance and attention to biosecurity should therefore be continued, especially over the winter season when there is arguably more contact between horses due to stabling and indoor competitions.