The Rural Voice, 1983-12, Page 36Ear Necrosis:
major problem
Ear necrosis has in recent years
escalated from an occasional condi-
tion seen sporadically in most hog
producing areas of the world to
become a major problem in many in-
tensive swine units in the U.S.
midwest. Submissions to the Huron
Park Laboratory of pigs with necrosis
of one or both ears have steadily in-
creased over the last year or two and,
in recent months, have become com-
monplace.
Briefly, ear necrosis is seen in one
or both ears of affected pigs. It starts
as a reddened area and becomes a
gray or brown discolouration at the
base and/or tip of an affected ear.
This may progress to ulceration with
scab formation. Lesions may heal
spontaneously and disappear com-
pletely. Alternatively, lesions may
progress to the extent that some or all
of the affected ear(s) may drop off.
Mortality is negligible, but in the
worst affected herds, morbidity may
approach 100 per cent. Reduced feed
conversion results, but the biggest
economic losses occur due to the un-
sightly and unacceptable blemishes to
replacement breeding stock.
Researchers at Purdue University,
Indiana, led by Dr. Jimmy Richard-
son (an OVC graduate), have recently
given us a start towards under-
standing the cause and progression of
ear necrosis in pigs. Based on their
findings, several things are now
known: (1) The disease starts at or
soon after weaning. (2) Trauma
(bruising) to the ear followed by
bacterial infection is the cause of the
disease. (3) The trauma is initiated by
fighting to re-establish social
dominance among recently weaned
pigs. (4) The main bacterium present
is Staphylococcus hyicus with Strep-
tococcus sp. also frequently present.
NB Staphylococcus hyicus is also
responsible for another well-known
skin disease of piglets viz. "Greasy
Pig Disease". (5) Ear biting (canni-
balism) is NOT a primary cause of
and only an incidental reason for pro-
gression of the disease. i.e. the ear
necrosis is not started by ear biting
and may worsen even if there is no ear
biting. (6) There is little or no
seasonal prevalence.
Treatment and control of this
ANIMAL SCIENCE
disease still elude us. Many treatment
and control programmes have been
developed by veterinarians in the
U.S. midwest. They are usually based
on reducing pen population densities,
upgrading sanitation and adding anti-
biotics, biotin and/or selenium to the
diet. Adherents have reported
"cures" for any and all of these
regimens. Unfortunately all of these
"treatments" are equally as likely
NOT to help. The same regimen that
"works" on one farm may be a.
dismal failure on the neighbouring
farm of the same size, using the same
feed and similar management prac-
tices, etc.
Ear necrosis in pigs appears to be
yet another disease emerging from the
intensive production systems of the
1970's and 80's. Thanks to these
researchers we have now started to
understand some of the factors
responsible for ear necrosis in pigs. A
great deal more work has to be done,
but a start has been made. ❑
Submitted by S. Ernest Sanford, Veterinary
Pathologist. Veterinary Laboratory .Services.
Ontario Ministry of Agriculture and Food.
Huron Park, Ont. VO.M11 11'0.
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THE RURAL VOICE, DECEMBER 1983 PG. 35