What is Equine Herpesvirus and which types matter most?

Equine Herpesvirus (EHV) is a family of horse-specific DNA viruses. The types that cause most serious disease in domestic horses are EHV-1, EHV-3, and EHV-4. EHV-1 is linked with respiratory disease, abortion, neonatal death, and neurologic disease (EHM); EHV-3 causes coital exanthema; and EHV-4 is mainly a respiratory pathogen, especially in young horses.

Can people or other pets catch EHV from horses?

No. EHV is considered a species-specific virus that infects equids, such as horses, donkeys, and mules. Current evidence does not support EHV as a zoonotic disease, so people and common companion animals like dogs and cats are not at risk of catching EHV from horses.

How does EHV usually spread between horses?

EHV spreads mainly through respiratory secretions, including nose-to-nose contact and shared droplets from coughing or snorting. It also moves via fomites such as shared buckets, tack, grooming tools, stall tools, and contaminated hands, clothing, and footwear. During an outbreak, preventing direct contact and assigning dedicated equipment to each group of horses is critical.

What are the early warning signs of EHV infection?

Early EHV signs often start with fever, sometimes before obvious respiratory changes. Common clinical signs include fever, nasal discharge, cough, enlarged lymph nodes, dullness, and reduced appetite. In some horses, particularly with EHV-1, disease can progress to abortion in pregnant mares or neurologic signs such as hind-limb incoordination, weakness, loss of tail tone, or difficulty urinating.

Is there a cure for EHV, and how is it treated?

There is no antiviral cure that eliminates EHV from the body. Treatment focuses on supportive care, such as anti-inflammatory medications, fluids for dehydrated horses, nursing care, and intensive management for neurologic cases including bladder support or slings when appropriate. Antiviral drugs may be used in select situations under specialist guidance but do not replace isolation and strong biosecurity.

Does vaccination prevent EHV outbreaks?

Vaccination against EHV-1 and EHV-4 helps reduce respiratory disease, abortion risk, and viral shedding, and is widely recommended as part of a risk-based vaccination program. However, current vaccines do not reliably prevent the neurologic form, EHM, and immunity is relatively short-lived, so boosters are needed in higher-risk horses. Vaccination must always be paired with quarantine, hygiene, and temperature monitoring to reduce outbreak risk.

What should I do if I suspect EHV in my barn?

If you see compatible signs such as fever clusters, respiratory disease, abortion, or neurologic changes, call your veterinarian immediately and hold all horse movement on and off the property. Start twice-daily temperature checks, isolate sick or febrile horses, and tighten cleaning and handling protocols while your vet coordinates testing, typically PCR on nasal swabs and other appropriate samples.

How long should I monitor temperatures and isolate after travel or an outbreak?

After travel to shows or sales, a common recommendation is to monitor temperatures once or twice daily for 10 to 14 days and limit nose-to-nose contact during that time. After a confirmed EHV outbreak, barns typically maintain quarantine and daily temperature logs for 21 to 28 days from the last new case, under the guidance of local animal-health authorities and the attending veterinarian.

Why is EHV-1 especially important in equine health?

Because it can cause respiratory disease, late-term abortion, neonatal death, and serious neurologic disease known as Equine Herpesvirus Myeloencephalopathy (EHM).

Common ways EHV-1 and EHV-4 spread through and between barns:

Nose-to-nose contact, shared respiratory droplets, shared equipment such as buckets and tack, and contaminated hands, clothing, and footwear of people moving between horses.

Which combination best fits a typical respiratory EHV-1/EHV-4 case?

Fever, nasal discharge, cough, swollen lymph nodes, lethargy, and reduced appetite.

Which set of signs should make you worry about possible neurologic EHV (EHM) and call your vet immediately?

Hind-limb incoordination, weakness, difficulty standing, poor tail tone, and urinary incontinence or retention.

What makes latent EHV infection a management challenge?

Horses can carry the virus silently and start shedding again under stress without obvious early warning, making it hard to know which horses are risk sources.

Which statement about EHV vaccination is most accurate?

Vaccination helps reduce respiratory disease, abortion risk, and viral shedding, but does not reliably prevent the neurologic form (EHM), so it must be combined with strong biosecurity.

Isolation and biosecurity steps that help prevent barn-wide EHV spread:

Quarantining new or returning horses for about 21 days, keeping pregnant mares separate from high-traffic horses, and cleaning and disinfecting equipment while changing clothes or washing hands between groups.

You suspect EHV is circulating in your barn. What are good first-hour management steps?

Call your veterinarian, restrict all horse movement on and off the property, and start temperature checks while isolating sick or fever-positive horses.