ABSTRACTS
243
inches. In a negligible percentage of cases (0.6%) the reaction may spread to the
gluteal region. It is suggested that badly affected tails should not be amputated
until dry necrosis has commenced; else, the inflammation may spread rapidly and
thus produce serious complications. It was also noticed that the rise in complement-
fixation titre and the duration of its persistence are directly proportional to the
virulence of the culture used for vaccination, and that the duration of immunity is
relatively shorter when less virulent strains of the organism are used. The use of the
most virulent culture consistent with safety is therefore emphasized for immunization.
In order to produce, if possible, a high degree of immunity reinforcement of tail
vaccination was attempted by following it up by subcutaneous inoculation, eight weeks
later, of a larger dose (2.0 c.c.) of culture behind the shoulder.
Controlled tests
made twelve months later, by exposure to infection by the atomization method,
showed that up to that period the " single " method of immunization was as highly
efficient as the " double " method. Serologically, however, the " double " method
produces a very rapid rise of complement-fixing antibodies which persist for several
weeks and then disappear slowly ; the " single " method on the contrary results in only
a slight rise which disappears rapidly. It is therefore considered possible that immunity
produced by the " double " method would, if tested after longer periods, be found to be
more durable.
Vaccinated animals were subjected to the usual serological tests. Small groups of
immunised animals were exposed, simultaneously with controls to artificial infection
by the atomization method. This showed that animals developed a high degree of resis-
tance even as early as the third or fourth day after vaccination.
The paper ends with, the method of preparation of the vaccine and the success
achieved by its use in the field. [M. Y. M.]
Enzootic pneumonia in sheep. R. F. MONTGOMERIE, T. J. BOSWORTH AND R. E.
GLOVER. (1938). J. Com. Path. Ther. 51, 87-107.
THE authors, after having investigated several outbreaks, have described an
enzootic form of pneumonia in sheep. The lesions were mostly confined to the
thoracic cavity. There was no direct evidence that the larvae of oestrus ovis, or
nematodes in the lung tissue, played any significant part in the causation of the disease.
A pasteurella-like organism was isolated in eighteen cases from the hepatised
lungs, out of the twenty-two cases available for bacteriological investigation. The
organism is encapsulated, haemolytic and indol negative and resembles Jones (1921)
group I Pasteurella. The different strains obtained were divided into two distinct
sub-groups by agglutination tests.
Sheep, rabbits, guinea-pigs and pigeons were refractory to experimental inocula-
tion by different routes with some of the strains which were, however, lethal to mice
when injected intraperitoneally in large doses. Suspensions of lung lesions from
natural cases of the disease when inoculated into healthy sheep induced definite
pathological changes in the lungs but the authors found it impossible to establish a
definite infective agent. The histopathology of the experimentally produced lung
lesions was not entirely similar to that seen in natural cases.