Report on the Agricultural Experiment Stations, 1952 Page: 67
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VETERINARY RESEARCH 67
Meanwhile at the Maryland station, it was found that the cotton
rat is susceptible by intracerebral inoculation to six different strains
of Newcastle disease virus which may involve the central nervous
In our last annual report it was stated: "the Virginia station
announces that vaccination by nebulization (spraying) with B1 vaccine
is practical and safe." During the past year this station has
adapted this spray technique for use on day-old chicks in boxes of
100-chick capacity. The results have been very encouraging. It
was possible to vaccinate 100 chicks every 3 minutes without extra
handling. There was no undue reaction from vaccination and a
satisfactory immunity was obtained. Use of this method will effect
a great saving in the labor and time required for vaccination.
Infectious Keratoconjunctivitis (Pinkeye) of Cattle
Research at the Texas station has shown that the bacterium,
Hemophilus bowis, is the causal agent of pinkeye in cattle. The organism
when grown on artificial media dissociated into smooth and rough
colonies, but only the former produced infection when introduced into
the eyes of susceptible cattle. It was also found that a formaldehydekilled
bacterin containing the smooth type colony of H. bovis resulted
in a solid immunity up to 6 months, whereas injections of a viable
vaccine produced a still stronger immunity which resisted artificial
challenge up to 12 months. A practical method for the preparation
and suspension of the vaccine that involves the use of solid media for
growth, a spray technique for inoculating the media, and a formula
for obtaining an even suspension of the vaccines have been developed.
Immunization Against Hog Cholera
Preliminary studies at the Virginia station show that nitrogen mustard
will attenuate the virus of hog cholera. This attenuated virus is
highly antigenic and develops satisfactory immunity to pen and
artificial exposure. The attenuated virus produces no ill effects in
injected pigs, and such pigs are of no danger to noninjected, susceptible
pigs. The treated virus can be used up to 24 hours after its preparation.
These findings offer an additional means of preparing an
immunizing agent against hog cholera, one that does not have the
limitations of the serum-virus method. The studies are being continued
in order to determine the duration of protection, and other
factors which may affect use of this material.
Treatment of Ketosis in Dairy Cattle
Ketosis has been of increasing importance since it was recognized
about 20 years ago. Cows affected with it lose their appetites, lose
weight, and drop off in milk production. They may make a gradual
recovery without treatment, but there is a loss of milk for several
The Maryland station, after 6 years of intensive study of ketosis,
reports that cortisone is a cure for this condition. The station has
observed that first symptoms of ketosis appear at about the ninth day
after calving, at which time the blood sugar had fallen to a low level.
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1952, book, January 1953; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5990/m1/69/: accessed August 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.