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Better Pork
June 2016
HERD
HEALTH
it has become almost nonexistent since
we moved to total indoor, confinement
rearing of pigs over the last 50-60 years.
Pathogenesis
. Leptospira invade
mucous membranes (eyes, mouth,
nose, vagina), wounds and cuts and also
enter via transplacental transmission or
sexual contact. Once they have entered
the host, the organisms then multiply to
produce a septicemia which may gener-
ate clinical signs. The kidney, liver and
other internal organs may be damaged.
Leptospiral organisms are shed inter-
mittently in the urine for months after
clinical signs cease. Organisms localize
in the pregnant uterus, causing fetal
invasion and abortion 10 days to four
weeks after infection.
Clinical signs
. Acute infection in
young piglets may result in fever, loss of
appetite, jaundice, convulsions and fail-
ure to grow and gain weight. Chronic
infection in sows presents as various
forms of reproductive failure, including
poor conception rates, late-term abor-
tions, stillborns, dead or weakborn pigs
and neonatal mortality accompanied by
fever, loss of milk and jaundice. Mum-
mified fetuses also occur commonly
among litters of sows with leptospirosis.
Diagnosis
. Abortions in the last tri-
mester of pregnancy, weakborn piglets
and fever with jaundice and mortality
in older piglets and weaners suggest
leptospirosis. Confirm the diagnosis by
demonstrating rising antibody titres to
the incriminating strain of Leptospira
spp.
Treatment and control
. Many anti-
biotics are effective against leptospires,
but control measures consisting of
vaccination of breeding sows with killed
vaccines containing the appropriate
serotype(s) are the preferable methods
to prevent reproductive failure from
leptospirosis.
Listeriosis (Listeria monocytogenes)
Listeriosis is a disease caused by the
bacterium
Listeria monocytogenes
. It
lives in the tonsils of pigs and other
animals and is shed in their feces, where
it contaminates soil and crops. Listerio-
sis is uncommon as a primary disease in
pigs, but it may cause fever, septicemia,
central nervous system signs and abor-
tion. A major concern with
L. monocy-
Acute Leptosphirosis
infection in young
piglets may result in
fever, loss of appetite,
jaundice, convulsions
and failure to grow and
gain weight.