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What is Equine herpesvirus?
Equine herpesvirus (EHV) is a contagious viral
infection which can cause respiratory disease,
abortions and neurological disease in horses.
There are two main types of EHV which
cause disease:
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EHV-4 is very common and causes
respiratory disease;
●
EHV-1 is less common, but can have
severe effects, causing abortion and
neurological disease.
Most horses are first exposed to the disease
as youngsters, with the vast majority of our
horses exposed to EHV throughout their lives.
The effects of disease on a breeding
establishment can be devastating, but even
on livery or competition yards, entire seasons
can be compromised due to EHV infection
affecting performance and well-being.
What are the symptoms?
In respiratory disease the clinical symptoms
may include a rise in body temperature,
nasal discharge and a dry cough in younger
horses. The horse may also show signs of
depression and lethargy. However you can
commonly have a disease scenario with
no obvious symptoms, just depressed
performance or recurrent airway infections
in the horses.
In breeding mares, EHV-1 is the most
commonly diagnosed cause of infectious
abortion. Abortion usually occurs in the last
third of pregnancy, but as a previous infection
can leave a horse as a carrier, there may be
no clinical signs prior to abortion.
Very rarely EHV-1 infection can cause
a neurological disease - horses may
become paralysed and are given a very
poor prognosis.
How is EHV transmitted?
EHV is a highly contagious viral disease.
It passes from horse to horse through the
respiratory tract as viral particles are
breathed in from infected horses.
Once a horse is infected with EHV, it can
harbour the virus throughout its life and
potentially 'shed' the disease to other animals.
Horses shed EHV at times of stress, for
example moving yards or when under other
disease challenge.
The main concern for the equine population
is the way the disease persists in our horses
and, since natural immunity is short-lived,
horses can remain at risk from EHV despite
previous exposure. This is why ongoing
control and vaccination are so important.
What can I do to prevent my
horse getting EHV?
Control of EHV-1 and EHV-4 is based on
prevention and limiting the spread of disease
if it occurs.
●
Stable management, in particular when
dealing with potentially infected horses,
is key to the control of the disease. Try to
minimise stressful situations for your horses
as much as possible and isolate sick or
new horses.
●
Vaccination can play a big role;
vaccinating your horse will help reduce
the severity of clinical signs. But perhaps
more importantly vaccination can reduce
the spread of the EHV by reducing the
amount of infective virus that is shed onto
other in-contact horses.
Vaccination is more effective when enough
horses are covered for a 'herd immunity'
strategy to work. The same collective principle
is true of management strategies. A yard
approach is the best way to manage the
threat of this common disease - discuss it with
your vet for help and information on the best
approach for your horses.
Equine herpesvirus:
The facts
Veterinary Surgeon
Ben Gaskell
XLVets Equine Practice
Minster Equine Practice
Ben Gaskell BVSc MRCVS
, Minster Equine Practice
EQU INE HERPESV I RUS
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EQUINE MATTERS