EQUINE | Equine Disease Quarterly
Equine Disease Quarterly –
April 2019
COMMENTARY
The recent increased incidence of equine influenza
in the United States and abroad necessitates
implementation of prevention and control strategies to
protect the health of the equine population. Although
vaccination plays an important role, it should not be
relied on as the sole preventative. Similar to other
influenza viruses, equine influenza virus mutates over
time and vaccines must be periodically updated to
keep current with circulating viruses. Horses that have
been vaccinated in accordance with manufacturer’s
label instructions and the recommendations of
American Association of Equine Practitioners may be
protected against equine influenza. Studies suggest
the use of the modified live intranasal vaccine in
previously unvaccinated horses can provide protection
within five days of primary administration. However,
no vaccine is 100% effective. Investigations into recent
cases indicate that vaccinated horses can develop mild
clinical signs of short duration, whereas unvaccinated
horses are more severely affected and more likely to
develop secondary pneumonia and pleuritis.
Implementation of biosecurity measures is essential to
protecting the health of horses during influenza season.
As influenza virus is spread most readily through nose-
to-nose contact, it is critical to limit horse-to-horse
contact and require strict isolation of new arrivals
and sick horses. Infected animals should be kept at a
minimum distance of 50 yards from healthy horses.
24
If no suitable permanent isolation stable is available,
then designate an area on the property where a
temporary isolation structure can be erected. When
no appropriate onsite isolation areas are identified,
consider appropriate off-site isolation facilities such as
vacant barns, empty fair or event grounds, or veterinary
clinics. To prevent virus transmission, designate
personnel and equipment to the isolation area.
Disposable coveralls, gloves, and boot covers should
be used when handling horses in isolation. Personnel
who must care for animals both in and outside of
isolation should handle healthy animals first and
isolated animals last. Individuals caring for exposed
or infected horses should utilize alcohol-based hand
sanitizers after handling all horses.
Influenza virus can be inactivated by exposure to
sunlight or by use of disinfectants. The virus can remain
viable for up to 2 days on contaminated surfaces,
specifically solid surfaces of stall door latches. Thus,
any shared equipment should be thoroughly cleaned
and disinfected between uses.
The critical factor in controlling and preventing the
spread of influenza virus is monitoring the health of all
equids. Monitoring includes taking body temperatures
twice daily and recording all clinical observations.
Only healthy horses, which have been monitored,
should be permitted to leave the premises. Any horse
showing clinical signs of respiratory disease should be
immediately isolated and examined by a veterinarian.
• Equine Health Update •