The Rural Voice, 1982-10, Page 32ANIMAL SCIENCE
B.V.D. - Bovine Virus Diarrhoea
BY Stan J. Alkemade, B.V.Sc., D.V.M.,
M.R.C.V.S.
Bovine Virus Diarrhoea (B.V.D.) is a
viral disease of world wide occurrance in
beef and dairy cattle, characterised clas-
sically by two syndromes. In the acute
form of the disease young animals,
generally twelve to twenty-four months of
age, scour profusely, do not respond to
treatment and subsequently die. A chro-
nic form of the disease, often called
Mucosal Disease, causes ulceration of the
muzzle, tongue, pharynx and intestinal
tract leading to a decreased food intake,
poor food conversion, loose manure and
loss of condition or milk production.
During the last fifteen years, two and
possibly three, new forms of the disease
have been recognized. The virus is capable
of crossing into the uterus and, during the
first six to seven months of pregnancy,
may cause infection and death of the
developing calf, with subsequent resorp-
tion, mummification or abortion. Some
calves infected at the transition period of
6 - 7 months of pregnancy, may survive to
be born hairless and/or with mild to
severe nervous system disturbances. New-
born calves can develop a B.V.D. viral
infection in the first months of life leading
to scours and death. Recent clinical
observations in vaccinated herds in the
U.S.A. and Canada indicate a possible
link between the B.V.D. virus and
calfhood pneumonia. Whether the virus
actually causes lung infections or merely
decreased the animal's resistance to other
infectious micro organisms is an area for
investigation. It is known that the B.V.D.
virus can decrease an animal's normal
immune responses and this may be the
explanation.
B.V.D. is normally spread from one
animal to another by the ingestion of
infected, fecal contaminated food or
water. Additions to the herd of clinically
normal, carrier animals is the common
method of transmission between herds.
Once the disease gains entrance to a herd
most of the susceptible animals will
become infected, show little or no clinical
signs, and develop a strong immunity to
OC ALFA -LAVAL and
LENCO Dairy Supply Ltd.
R.R. 1, Atwood 356-2282
ANNOUNCES:
Mr. Jim Boak
R.R. 5, Lucknow
357-1220
Sales and Service
Jim is well qualified to serve you with the latest in dairy equipment as he was
himself a dairy farmer and an ALFA -LAVAL user. Phone him and he will be glad
to discuss your requirements with you.
Pipe lines - Parlor - Bulk Milk Tanks - Plate Cooler -
Energy Savers - Milk Meters - Water Conditioners - Water Bowls
Ration Master Computerized Feeding Systems.
PG. 32 THE RURAL VOICE OCTOBER 1982
the disease. Less than 10070 of the herd
will develop the acute or chronic diar-
rhoeic forms of the disease. Unfortu-
nately, however, a larger proportion of
females less than six to seven months
pregnant may either abort or return to
service. This is drastic in a beef herd but
can also be devastating in a dairy
operation.
Vaccines for the prevention of B.V.D.
have been commercially available for a
number of years but their use has been
questioned. New clinical and research
data indicates that B.V.D. vaccination, in
combination with other herd health
preventative programs, has helped to
reduce herd infertility problems as well as
calfhood diarrhoea and pneumonias.
A number of things should be con-
sidered before a vaccination program is
established.
1. Pregnant cows vaccinated during the
first six to seven months of gestation
may abort.
2. Calves which suckle colostrum from
protected animals will not develop
their own protection if vaccinated
during the first two to three months
of life.
3. Calves from cows vaccinated during
the last two months of pregnancy will
develop their own circulating protec-
tion while still in the uterus.
4. Some animals are immunologically
incompetent and will not develop
circulating antibodies to the natural
or modified vaccine virus.
If a vaccination program against
B.V.D. is to be incorporated into the
normal herd health procedures, it can
often be associated with other vaccines;
e.g. I.B.R. AND PI3. The basic recom-
mendations would be to vaccinate all
mature females during the first thirty days
after calving, and in problem herds to
booster this with a second vaccination
during the last two months of age and a
second vaccination at 8 to 12 months. In
problem herds, heifers should probably
be re -vaccinated just prior to breeding.
Although B.V.D. has normally been
considered a disease of beef cattle it has
assumed greater importance in dairy
herds over the last five years and is
becoming more prevalent in this area of
S.W. Ontario. Your local veterinarian can
help diagnose the disease from the clinical
history of your herd and a clinical
examination of your animals. He or she
can confirm the disease with blood
samples.
Not all veterinarians agree with vac-
cinating against B.V.D., especially in
herds with a history of clinical cases, and
his or her advice is the best for your
particular herd.