Equine Disease Quarterly | EQUINE
the rule of thumb is that for every day of fever, it
should be stall-rested for a week.
2. Vaccinate your horses using a vaccine that protects
against both FC1 and FC2 viruses. Horses’ antibody
responses to vaccination do not last indefinitely,
so if your horse has not been vaccinated for six
months or more, then it is due for a booster. If it has
been three months or less since the last booster,
then hopefully your horse’s immunity should be
at its peak. Consult your veterinarian and refer to
the AAEP Guidelines (https://aaep.org/guidelines/
vaccination-guidelines/risk-based-vaccination-
guidelines/equine-influenza). In the event of an
EI outbreak, where your horse may potentially be
exposed, vaccination in the immediate face of the
event might help if there is sufficient time—at least
a week—for the horse’s immune system to start
making antibodies.
3. Communicate with your veterinarian and with the
manager or resident veterinarian at any facility
to which you are taking your horse. Is there an
outbreak situation? If so, re-evaluate your horse’s
vaccination status, and re-evaluate exposing your
horse to flu.
4. Biosecurity from infectious diseases is best
enforced by avoiding exposure whenever possible.
For farms, the best biosecurity is obtained by
quarantining newly arriving horses away from
the general herd for sufficient time to assure that
the new arrivals are not bringing diseases with
them. EI is transmitted through the air by coughing
and indirectly on hands or clothing/ equipment
(fomites) that have been in contact with an infected
horse.
CONTACT:
Thomas Chambers, PhD
[email protected]
(859) 218-1126
Maxwell H.Gluck Equine Research Center
University of Kentucky
Lexington, KY
Equine Neorickettsiosis: Incidence in Kentucky in
2018
Equine neorickettsiosis (EN), more commonly known
as Potomac horse fever, is an equine-specific bacterial
disease caused by Neorickettsia risticii. The disease
was first reported in the USA in 1979 as a sporadic
condition observed in horses pastured in proximity to
the Potomac River. Current distribution is now known
to extend far beyond the northeastern United States
and has been reported in 43 states in the USA; three
provinces in Canada; Uruguay and Brazil in South
America; France and the Netherlands in Europe; and
in India. The disease is often associated with horses
grazing pastures bordering creeks or rivers. Equine
neorickettsiosis is seasonal in occurrence, with the
majority of outbreaks in Kentucky reported in July
through September.
The disease is not contagious per se; infection is
naturally acquired by horses accidentally ingesting
aquatic insects harboring metacercariae (fluke larvae)
infected with N. risticii.
The life cycle of the bacterium involves operculate
freshwater snails and aquatic insects viz mayflies and
caddisflies, the latter being the source of infection for
horses.
Outbreaks of EN comprise isolated or multiple cases
of the disease on a premises. Experience has shown
that the disease once confirmed on a premises or in a
particular area, tends to recur in subsequent years.
Neorickettsia risticii can cause an acute enterocolitis in
• Volume 21 Issue 2 | May 2019 •
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