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Equine influenza
Respiratory diseases
Disease causing agent
equine influenza virus
Incubation period
1-3 days
Transmission
aerosol (airborne droplets) spread, on hands and equipment
highly infectious and spreads rapidly
cross-species transmission to dogs can occur
Signs you will see
hacking, dry cough, high fever, loss of appetite
in vaccinated horses there is reduced viral shedding and therefore reduced risk of transmission to other horses
but horses may still show mild signs of disease
Diagnosis
virus is detected from nasopharyngeal swabs (long swab inserted up the nostril to swab the throat and nasal
cavity) and rising antibody levels in paired samples (figure1)
Treatment
rest, nursing and anti-inflammatory medicines
horses usually recover fully but can be fatal in older horses and young foals
long recuperation period required (may be several months)
Prevention
vaccination and good biosecurity practices
Equine Herpesvirus (EHV)
Disease causing agent
equine herpesvirus types 1 and 4 (EHV-1 and EHV-4)
Incubation period
variable - horses become latent carriers and can subsequently shed the virus
Transmission
close contact with an infected animal or contact with fluids following an abortion caused by the virus
Signs you will see
EHV can cause three types of disease:
1. mild respiratory signs with a cough, fever, nasal discharge and poor performance (EHV-1 EHV-4)
2. abortion in pregnant mares typically in later pregnancy, the mare aborts suddenly and without warning
(mainly EHV-1 but occasionally EHV-4)
3. rarely a neurological form (EHV-1) is seen with sporadic outbreaks or individual cases of hindquarter paralysis,
horses have difficulty walking, passing faeces or urine, or even become unable to stand (these horses may not
recover)
Diagnosis
virus detection from nasopharyngeal swabs or aborted material from mare, and rising antibody levels in blood
samples (figure 1)
Treatment
rest, nursing, anti-inflammatory medicines and in some cases antiviral medicines
most horses recover completely but may need a long recovery period
Prevention
keep brood mares separate from all other horses (especially young horses and those competing)
good biosecurity practices and vaccination
isolate brood mares and follow the HBLB code of practice for EHV (http://codes.hblb.org.uk)
Figure 1
In the diagnosis of infectious respiratory disease
early investigation is important; there is a short three
day window following the onset of signs when the
infectious agent can be identified with a swab. After
this time diagnosis can only be made on the basis of
paired blood samples taken fourteen days apart.
Common contagious equine diseases in the UK
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