UPDATE ON HEMORRHAGIC SYNDROME IN VEAL CALVES The abstract is reprinted from JAVMA Feb. 15,
1990, pg. 590. The most frequently encountered infectious
agents isolated from cases of hemor-rhagic syndrome at ADDL
are bovine virus diarrhea, Pasteurell a haemo1ytica.Escherichia
coli.and Salmonella sp. Furazolidone,neomycin,mycotox-ins,
and polyunsaturated fatty acids have also been suggested as
toxic agents that this syndrome. None have been documented
date.
The abstracted research observations provide stronger evidence
that BVD may be the primary factor involved in hem-orrhagic
syndrome. In cases fully investigated by ADDL, BVD has been
identified most often of any infectious agent. However, P.
haemolytia and/or one of the other gram negative agents is
usually isolated a1 so.
THROMBOCYTOPEN1 A AND HEMORRHAGES IN VEAL CALVES INFECTED
WITH BOVINE VIRAL DIARRHEA VIRUS.
Wayne V. Corapi,DVM,PhD;R. Dean Elliott, DVM; TracyW. French,
DVM; Donald G. Arthur, BVSc; David M.Bezek, DVM; Edward
J.Dubovi, PhD.
SUMMARY: The relationship between bovine viral diarrhea
virus (BVDV) infection and thrombocytopenia was studied
in 18 veal calves experimentally infected with BVDV. All
calves were free of BVDV, and 13 calves were free of serum
neutralizing antibodies to BVDV before virus inoculation.
Calves were inoculated at approximately 10 days of age,
and platelet counts were monitored over a period of several
weeks. Ten additional calves housed "in close proximity
were kept as umnoculated controls. A profound decrease in
platelet counts by 3 to 11 days after inoculation was seen
in all calves that had neutralizing antibody titers <1:32
before infection. Severe thrombocyto-penia (<5,000 p1atelets/ul)
was seen in 12 calves, 11 of which also developed hemorrhages,
Necropsy findings in 3 severely thrombocytopenic calves that
died included multiple hemorrhages throughout the body. Calves
that recovered had increased platelet counts, and in most
instances, a corresponding increase in neutralizing antibody
titers to BVDV. At 11 days after inoculation, BVDV was detected
on platelets by use of immunofluorescence, but evidence of
surface-bound immu-noglobulin was not found. The results
suggest that a non-im-munoglobu1in-mediated method of platelet
destruction or sequestration develops as a sequel to BVOV
infection.
Drs.T.L.Bowersock, Chief of Microbiology, and M.R White,
Veterinary Pathologist |