News from Lambourn Equine Vets

EHV Neuro Case Hampshire 2020

As many of you are aware from the social media posts, an outbreak of Equine Herpes Virus Type 1 has been confirmed earlier this week in Hampshire.  Crofton Manor have confirmed cases and are now closed to avoid any further potential spread. However, prior to confirmation of the diagnosis a show was held at the centre last Saturday 4th January 2020.  Understandably this is a cause for concern for those who attended that show however the risks remain low, but sensible precautions should be taken to avoid further spread. Here is a little more information regarding the disease and our recommendations.

Equine Herpes Virus

EHV causes four clinical syndromes: 

1) Respiratory 

2) Abortion 

3) Neonatal foal death 

4) Neurological disease – Equine Herpes Myeloencephalopathy (EHM) may or may not be related to previous or on-going respiratory disease

Respiratory Disease: What to look out for  

High temperature. (Fever)  Coughing  Nasal Discharge  Generally unwell, not eating or drinking normally. 

Neurological Disease: What to look out for  

Change in behaviour pattern.  Incoordination of the hind (and occasionally fore) limbs  Urine retention/dribbling  - can present as mild colic  Bladder weakness  Recumbency (inability to rise)  Neurological signs may be preceded by fever and respiratory signs. 

Transmission: How is the disease spread?  

Aerosol – most common route. Inhalation of droplets from coughing and snorting, shedding can last typically 7-10 days but can persist much longer 

Indirect Transmission – Fomites The virus can be live in the environment for a couple of weeks. Fomites (e.g. people, tack, yard equipment) can pass the virus between horses.

Therefore at least 28-day isolation period is recommended after diagnosis and blood tests and swabs can be taken from clinical cases to identify when it is safe to mix again with the wider population. 

Incubation Time:  May be as short as 24hrs but typically 4-6 days but can be longer up to 14 days for neurological signs 


Blood tests to detect that a horse has been exposed to EHV, involves paired bloods two weeks apart to see if the horse "seroconverted" i.e. the amount of antibody in the horses blood stream increases in response to the infection

Swabs are only of value when the horse is showing clinical signs to confirm a positive case, sadly they are not affective at screening in contacts. 

What Should I Do if I attended the Show with my Horse?  

Maximise Biosecurity by that we mean;

a) Monitor your horses vital signs so temperature twice daily and record these, normal adults horses do not vary much and will remain below 38C or 100.5F

b) Monitor for respiratory signs i.e. breathing normally, no discharge from nose or eyes

c) Monitor your horses demeanour, you know you horse are they behaving normally

d) In an ideal world any horses that attended Crofton's show last Saturday should be isolated away from other horses for a 14 day period, however, in practical terms this isn't always possible and unnecessary stress does increase the risk of a horse becoming symptomatic so avoid unnecessary contact with other horses and be conscious on contact with that horse and then onto others, you as the human can transmit diseases from one horse to another

e) Eliminate shared water sources if you have them, sharing water or grazing increases the risk of spread of infection.

f) DO NOT VACCINATE YOUR HORSE if they have been potentially been exposed to the EHV outbreak this is contraindicated

g) If your horse shows any abnormal signs then contact us immediately on 01488 73755

EHV Vaccination

We do have a vaccine available for EHV 1 & 4, however, there is no evidence to show that vaccination prevents the neurological form and in fact it can be harmful in the face of an outbreak.  EHV vaccination helps to reduces the viraemia i.e. how much virus is able to develop within the horse and therefore amount it is able to shed.  Similar to other viral vaccinations, the EHV vaccine does not prevent your horse getting herpes, it relies on the whole herd being vaccinated which in turn reduces the amount of "viral load" within the population and therefore reduces the number of animals that become symptomatic and can reduce the extent of the symptoms. LEV encourages vaccination for EHV in performance horses i.e. sports horse and racing yards where all the horses on the yard are vaccinated regularly as part of the yards respiratory health program.  We also recommended vaccination of pregnant mares, and in contact bloodstock, to reduce the risk of abortion.  However, vaccination of a single horse has very little benefit.  In addition, if a horse is vaccinated whilst it is viraemic, by that we mean they have been exposed to the virus and the virus is within the horses body, research has shown that this has potentially detrimental effects and there is an increased risk of the horse developing the neurological form of the disease.  In addition, vaccination in the face of an outbreak can add confusion to the horses "serological" state which makes confirmation of clearance even harder.  In short, whilst we would encourage yards to consider EHV vaccination as part of their herd health program in the future, we would discourage reactive vaccination at this stage.