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Better Pork
October 2016
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cally mild and short lived. The big
concern over SVV/ SV-A is its clini-
cal similarity to the very significant
vesicular FADs of FMD, SVD, VS
and VE. This became all too real in
October 2015 when pigs with vesicles
arrived at a slaughter plant in On-
tario, causing a temporary shutdown
of the plant until tests proved that the
pigs did not have any of the FADs.
That was a close call that nevertheless
had financial repercussions. Of even
greater concern is the very real pos-
sibility of shutdown of international
borders and disruption of trade
should pigs with similar vesicles
show up at an international border.
The shutdown would be much more
costly and could last for a much lon-
ger period before tests clear the pigs
of infection with any of the FADs.
In November 2014, reports from
Brazil described acute outbreaks of a
disease characterized by:
1. Vesicles and coalescing erosions on
snouts and coronary bands in sows;
2. Acute death of neonatal piglets (30
to 70 per cent) in the first four days
of life; and
3. Self-limiting outbreaks that lasted
one to two weeks.
Occasionally, vesicles and erosions
on the coronary bands were present
in convalescing piglets. Reports were
initially limited to acute significant
losses of newborn piglets. Losses
were sometimes associated with
lethargy, nervous signs and/or diar-
rhea in neonatal piglets. Samples of
vesicular fluid and blood sera sent to
the University of Minnesota Veteri-
nary Diagnostic Laboratory tested
negative by PCR for FMD virus, SVD
virus, VS virus and VE virus. SVV/
SV-A was identified when more in-
tensive, next-generation sequencing
tests were done at the university’s lab.
This disease outbreak in Brazil is
a distinct departure from previous
SVV/ SV-A cases described from
other countries around the world in
the degree of its severity and high
levels of mortality in suckling pigs,
which had not been reported in other
previous outbreaks.
Cautionary note
Because of the clinical similarity
to the reportable vesicular diseases
(FMD, SVS, VS and VE), it is im-
perative that if vesicles are seen on
pigs the herd veterinarian be con-
sulted immediately, who will then
contact the Canadian Food Inspec-
tion Agency, whereupon tests will be
conducted to rule out the afore-men-
tioned reportable vesicular diseases.
Summary
Seneca Valley Virus, now called Sen-
ecavirus A (SV-A), is a non-envel-
oped, single-stranded RNA virus in
the family Picornaviridae, the same
virus family as Foot-and-Mouth
Disease (FMD) virus and Swine
Vesicular Disease (SVD) virus. The
disease from SVV/ SV-A clinically
resembles Vesicular Stomatitis (VS)
and Vesicular Exanthema (VE), all of
the above being vesicular diseases of
pigs (and other livestock species) and
are reportable foreign animal diseases
(FADs). SVV/ SV-A has been known
for some time, having been reported
previously in the United States, New
Zealand, Australia and Canada.
The Canadian case came from
Manitoba in 2007 when 187 pigs
shipped from Manitoba to a U.S.
slaughter plant arrived with vesicles
on the snout. Tests at diagnostic lab-
oratories ruled out all FADs. Clinical
signs of SVV/ SV-A are characterized
by the formation of vesicles, erosions
and ulcers on the skin, oral cavity
and coronary band at the hoof/ skin
junction on the feet, lesions typically
seen in the vesicular FADs of FMD,
SVD VS and VE. Lesions can be seen
in all ages of pigs, including suck-
lers, weaners, growers, finishers and
mature sows and boars. Although
not itself a particularly severe disease
in pigs, its clinical similarity to the
vesicular FADs is cause for concern
in the event that a clinical outbreak
is dismissed as SVV/ SV-A without
diagnostic confirmation and the
outbreak might really be one of the
FADs.
BP
S. Ernest Sanford, DVM, Dip Path, Diplomate
ACVP, is a swine veterinary consultant in
London, Ontario.
HERD
HEALTH
13160449/Creative RF/Getty Images
Seneca Valley virus is usually clinically
mild and short-lived.