Calf
Scours Caused By a Variety of Pathogens
NEW
YORK (Oct. 28, 2009) — One of the reasons why calf scours is such a
challenging disease for producers is that it can be caused by a combination of
two or more pathogens.
“There
are four major pathogens that cause calf scours, and a host of minor ones,”
said Jerry Olson,
He
added that diagnosis of the pathogen(s) involved in scours is challenging
because the causative agent may no longer be present by the time the sample is
collected and tested at a diagnostic laboratory, and some scours organisms also
may be present in healthy calves. Postmortem exams also can be unreliable
because dead animals often have intestinal bacterial overgrowth and/or
postmortem tissue destruction.
While
diagnosis based strictly on clinical signs is not possible, Olson noted some of
the characteristics of major scours pathogens:
¨
Escherichia
coli K99
should
be suspected as a cause of scours in calves during the first week of life.
¨
Rotavirus
serotype G6
and rotavirus serotype G10 also
can surface in the first two weeks of life, but may be involved in animals a
month of age or older. Infections involving either serotype of rotavirus often
cause animals to have profuse watery diarrhea because the absorptive capacity of
the gut is markedly reduced when the intestinal villi are blunted.
¨
Coronavirus
usually
causes more severe scours outbreak than rotavirus because it affects
both the small and large intestine whereas rotavirus affects primarily the small
intestine. Coronavirus primarily affects calves from one to three weeks of age.
However, like rotavirus, it may occur any time during the first month of a
calf’s life and beyond.
Both
rotavirus and coronavirus are hardy organisms that can survive for months in
moist, cool conditions.
Scours
treatment is a frustrating proposition. “Infected animals very quickly have
problems with nutrient malabsorption, excess secretion of fluids and intestinal
inflammation,” Olson said. “Once these factors start to snowball, their
combined effect is difficult to overcome.”
Olson
advised that prevention is the most efficient approach to managing scours.
Passive immunity created by vaccinating the dam and getting adequate quantities
of high quality colostrum from these vaccinated cows shortly after birth are
very effective in preventing diarrhea caused by E.
coli, rotavirus and coronavirus.
Olson
said that, ideally, for maximum protection of the calf, vaccination of the dam
should take place far enough ahead of the “colostrum concentration” window
that high levels of antibodies are present in the blood at its onset. This
starts at about three weeks before calving, and peaks during the last two weeks
before calving. This means that cows need to receive a booster at least three
weeks prior to the IgG concentrating period.
ScourGuard®
4KC is the only vaccine labeled for protection against rotavirus serotypes G6
and G10. ScourGuard 4KC also aids in preventing diarrhea caused by
coronavirus, E. coli K99 and Clostridium
perfringens type C. Olson advised that first-calf heifers
should receive a two-dose vaccination regimen, given approximately three weeks
apart. The first dose should be administered in the seventh or eighth month of
pregnancy, with the second dose given five to six weeks before calving. After
that, an annual booster shot given five to six weeks before each subsequent
calving is recommended.
Pfizer
Animal Health, a business of Pfizer Inc (NYSE: PFE), is a world leader in
discovering and developing innovative animal prescription medicines and
vaccines, investing an estimated $300 million annually. Beyond the
###
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