(23)Acute
diarrhea is common and is
one of the most important diseases in newborn calves from both dairy
and beef
herds throughout the world (1).
The most
frequent consequences of neonatal
diarrhea
include a significant increase in morbidity,
mortality and treatment
costs,
poor growth and greater susceptibility to other infections (especially
respiratory infections) (1).
Diarrhea
has a complex multifactorial etiology
which is
influenced by infectious, nutritional and environmental factors as well
as
management practices (1).
Suggested
causes of neonatal diarrhea include
toxins,
bacteria, protozoa, viruses, management and environmental factors
(overfeeding,
low temperature, poor hygiene and colostrum
deprivation) and the
individual
animal’s susceptibility (1).
Some
bacteria
associated with scours are E. Coli, Salmonella (typically S.
typhmurium), and
Clostridium perfringens type C and D (5).
Protozoa that have been known to
cause
scours include coccidia, cryptosporidium and to a lesser extent,
giardia (5). The
most common viral causes of scours are rotavirus and coronavirus,
bovine virus
diarrhea virus (BVD) is also associated with scours but it is not
overly common
in young calves (5).
Scours occurs when
normal movement
of water into and out of the digestive tract is disrupted (5). This results
in loss
of fluids and electrolytes, leading to dehydration (5). The general mechanism by which
intestinal viruses cause
diarrhea is via multiplication within enterocytes,
as the epithelial
cells are
destroyed, villous atrophy
develops resulting in malabsorption of fluid
and
electrolytes (15).
