Pig International - July/August 2017 - 23
PigInternational ❙ 23
ceed. Mass vaccinate sows every 3
to 4 months, and the pseudorabies
virus will cease to circulate in the
sow herd - and a PRV-negative
pig is weaned.
■ Control concurrent diseases.
Diagnosis of herd problems
should be done and efforts made
to control major concurrent problems. Pigs with chronic PRRS
and PCV2 fed suboptimal diets
in poorly ventilated barns are not
able to resist PRV, no matter how
frequently they are revaccinated.
■ All-in/all-out management.
PRV-negative pigs vaccinated
and managed in an all-in/allout system will remain negative. Exposure control is essential.
The grow-finish virus factory
must be shut down. Pigs should
be in groups with not more than
2 week age intervals within each
room or air space. Before a new
batch of pigs is introduced, rooms
are completely emptied, cleaned
with an alkaline detergent and
disinfected with a strong disinfectant. This system can produce
PRV-negative gilts if all-in/allout principles are not violated.
All-in/all-out by grow-finish site
is a good plan, but all-in/all-out
by air space can succeed.
before transport and tested again at
the destination farm while still in
their mandatory 60-day isolation.
The virus does not spread among
vaccinated sows even if positive,
and with simple biosecurity measures, a farm will become negative
for PRV by natural attrition and
culling of positive sows in 2 to 3
years. PRV has been eliminated as
an economic threat in many pork
production systems by this method,
and regions and whole countries
can become free of pseudorabies. ■
Accomplishing PRV elimination
Only gE-negative gilts
and boars are fit for replacements. Incoming breeding animals
must be tested negative for PRV gE
E. Wayne Johnson, DVM, is
senior technical consultant at
Enable Ag-Tech Consulting,