Pig International - July/August 2017 - 21

PigInternational ❙ 21

Chronic PRV in pigs
Chronic enzootic PRV is a pneumonia and cough in
growing-finishing pigs. Pigs under continuous-flow management become infected at about 10 to 12 weeks of age as
the long-lasting maternal antibody levels fall and the virus
begins to move pig to pig. The grow-finish system becomes
a pseudorabies virus factory, and the virus attacks the upper and lower respiratory tract. Secondary infections with
Strep, Pasteurella, Actinobacillus and Mycoplasma are
common. PRV is intensified by PCV-2, PRRS and CSF. 

How PRV is spread
PRV is spread by contaminated trucks and infected
breeding animals. It exists in nasal and oral secretions
and semen, but it is absent from feces and urine. PRV
is spread by contact with infected pigs or contaminated
surfaces but can spread within the air space of a pig
barn. Cold weather tends to preserve PRV, and it can
spread from farm to farm over a distance of 3 km in cool,
moist air. PRV virus is destroyed in less than one week in
warm weather, and it is killed on clean surfaces by most
common swine farm disinfectants, except for iodines.   

Necropsy findings
Lesions at necropsy are not especially diagnostic
for PRV other than the occasionally observed white
necrotic foci in the liver and spleen of piglets that
have died from PRV. Tonsillar necrosis may be observed. The nasal cavity may be severely inflamed and
reddened or hemorrhagic to fibrinonecrotic.  There is
interstitial pneumonia with interlobular edema that
may be superimposed on an anteriorventral bacterial pneumonia. Small blotches of hemorrhage and
necrosis may be seen on lungs. Histopathology reveals
a non-suppurative to mixed-cell meningoencephalitis. Perivascular cuffing and gliosis are common. There
may be focal necrosis in the liver, bronchi and bronchioles, the lung parenchyma, tonsil and sometimes the
gut. Sometimes, intranuclear inclusions are observed.

Differential diagnosis and confirmation
PRV can resemble PRRS, PCV-2, classical swine
fever (CSF), Actinobacillus pleuropneumonia (APP),
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Table of Contents for the Digital Edition of Pig International - July/August 2017

Pig International - July/August 2017
Contents
Pigs and Money
Industry Happenings
World pork production to grow at a slower rate
5 ways phytogenics improve pig feed efficiency
Methionine beyond protein synthesis in growing pigs
Understanding pseudorabies in pigs leads to prevention
6 fiber insights for formulating livestock feed
Salmonella control: Do organic acids solve the problem?
How lactic fermented feed benefits pig production
How to treat iron deficiency in neonatal pigs
Products
Marketplace
Advertisers’ Index
Pig International - July/August 2017 - Pig International - July/August 2017
Pig International - July/August 2017 - Cover2
Pig International - July/August 2017 - Contents
Pig International - July/August 2017 - Pigs and Money
Pig International - July/August 2017 - Industry Happenings
Pig International - July/August 2017 - World pork production to grow at a slower rate
Pig International - July/August 2017 - 5
Pig International - July/August 2017 - 6
Pig International - July/August 2017 - 7
Pig International - July/August 2017 - 8
Pig International - July/August 2017 - 9
Pig International - July/August 2017 - 5 ways phytogenics improve pig feed efficiency
Pig International - July/August 2017 - 11
Pig International - July/August 2017 - 12
Pig International - July/August 2017 - 13
Pig International - July/August 2017 - Methionine beyond protein synthesis in growing pigs
Pig International - July/August 2017 - 15
Pig International - July/August 2017 - 16
Pig International - July/August 2017 - 17
Pig International - July/August 2017 - 18
Pig International - July/August 2017 - 19
Pig International - July/August 2017 - Understanding pseudorabies in pigs leads to prevention
Pig International - July/August 2017 - 21
Pig International - July/August 2017 - 22
Pig International - July/August 2017 - 23
Pig International - July/August 2017 - 6 fiber insights for formulating livestock feed
Pig International - July/August 2017 - 25
Pig International - July/August 2017 - Salmonella control: Do organic acids solve the problem?
Pig International - July/August 2017 - 27
Pig International - July/August 2017 - 28
Pig International - July/August 2017 - 29
Pig International - July/August 2017 - How lactic fermented feed benefits pig production
Pig International - July/August 2017 - 31
Pig International - July/August 2017 - 32
Pig International - July/August 2017 - 33
Pig International - July/August 2017 - How to treat iron deficiency in neonatal pigs
Pig International - July/August 2017 - 35
Pig International - July/August 2017 - 36
Pig International - July/August 2017 - 37
Pig International - July/August 2017 - Products
Pig International - July/August 2017 - 39
Pig International - July/August 2017 - Advertisers’ Index
Pig International - July/August 2017 - Cover3
Pig International - July/August 2017 - Cover4
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