Antibodies
form
and
react
to
a
vaccine.
When
vaccinated,
horses
develop
antibodies
to
the
virus
found
in
the
vaccine.
When
antibodies
are
present
following
exposure,
they
bind
to
flu
receptors
to
neutralize
the
virus.
As
the
virus
mutates
(or
drifts),
the
antibodies
become
less
effective.
Viral
strains
evolve
over
time.
Surface
antigens
change
or
drift.
When
exposed
to
a
drifted
virus,
antibodies
offer
some
clinical
protection,
but
may
have
less
direct
protection.
1,2
This
is
known
as
cross
protection.
While
cross
protection
may
offer
some
defense,
studies
show
horses
may
still
shed
as
much
as
an
unvaccinated
horse.
1
Consider
up-to-date
vaccines
to
protect
against
the
most
recent
drifts.
Direct
protection
is
best,
but
not
all
flu
vaccines
are
created
equally.
It's
critical
to
use
updated
vaccines
that
protect
from
newer
flu
strains
including
Florida
Clade
1
and
Clade
2
strains. CLADE
1:
A/eq/South
Africa/04/2003-
like
or
A/eq/Ohio/2003-like
use
3
CLADE
2:
A/eq/Richmond/1/2007-like
viruses
3
SOURCES 1
Cullinane
A
and
Newton
JR.
Equine
influenza
—
A
global
perspective.
Vet
Microbiol
2013:167(1-2):205-214.
Vetera
vaccines,
flustory.com.
Accessed
March
15,
2018.
2
Paillot
R,
Prowse
L,
Montesso
F,
et.
al.
Whole
inactivated
equine
influenza
vaccine:
Efficacy
against
a
representative
Clade
2
equine
influenza
virus.
IFN-gamma
synthesis
and
duration
of
humoral
immunity.
Vet
Microbial
2013:162(2-4)396-407.
Vetera
vaccines,
flustory.com.
Accessed
March
15,
2018.
3
OIE
Expert
Surveillance
Panel
on
Equine
Influenza
Vaccine
Composition,
OIE
Headquarters,
22
March
2017,
Conclusions
and
Recommendations.
http://www.oie.int/our-scientific-expertise/specific-information-and-recommendations/equine-influenza/.
Accessed
March
15,
2018
4
Sellers,
Lunn,
et.
al.
2011
ACVIM
Forum,
Gildea
et.
al.
2011
Vaccine
9214-9233.
Daly
J.M.,
MacRae
S.M.,
Newton
R.,
et.
al.
Veterinary
Journal
189
(2011)
7-14.
5
https://thehorse.com/132674/the-equine-immune-system/
©
2019
Covetrus.
All
Rights
Reserved.
No
copying
without
permission.
Not
responsible
for
typographical
errors.
Lit.
No.
19EQLS68
(03/2019)
Antibodies
are
produced
in
the
secondary
lymphoid
tissues.
These
tissues
include
bone
marrow
and
lymphoid
tissues
scattered
throughout
the
body.
5
Some
horses
may
have
only
mild
or
moderate
clinical
signs
of
disease,
but
have
heavy
virus
shedding
resulting
in
an
increased
risk
of
influenza
infection
at
population
level.
4
