P. G. PANDE 163
kept is small. On the results of their experiments, however, they came to the
conclusion that these animals were so susceptible by nature that the disease
when once introduced into a herd might readily spread by contagion. Consid-
ering the high susceptibility of these animals to Johne's bacilli as proved by
these authors, it may be stated, at least for India, where goats are kept in such
a large number that they form an important dairy stock of the country, that
the occurrence of Johne's disease in these animals is of considerable importance.
Regarding the source of infection, as far as this outbreak is concerned, it
may with some degree of certainty be said that the goats contracted the infec-
tion from cattle in which the incidence of this disease prior to its detection in
goats at the same farm was ascertained to be quite high. In May 1935, when
this herd was placed at the Sylhet Farm the chances of these animals catching
infection from cattle through a common pasture were considerable and the few
deaths which occurred amongst them in November 1935, may, in all probabi-
lity, be ascribed to Johne's disease in which an early diagnosis was complicated
by the presence of an overwhelming number of helminth parasites. On this
assumption the incubation period of the disease in goats may be stated to be
about six months.
Like Johne's disease in sheep in which, in most instances, spread of infec-
tion from cattle was not proved [McFadyean and Sheather, 1916], Holmboe
and Slagsvold [1934] in a natural outbreak of the same disease in goats failed
to establish its origin from infected cattle or any other possible sources of
infection, and their account of the disease suggests that there might, as in case
of Johne's disease in sheep [McEwen, 1939], exist a different strain of Mycobac-
terium paratuberculosis, responsible for the affection in goats.
As regards the actual nature of the caseating lesions in the mesenteric
lymph glands it may be pointed out that McFadyean and Sheather [1916]
from the materials of their cases proved, by guinea-pig inoculation experiments,
that such lesions in goats may occur entirely as a result of infection with
Johne's bacilli. The necessity of conducting similar experiments in the
present case was obviated by the history of the herd and the farm, and also
by the knowledge that tuberculosis in goats is extremely rare in India. Also,
it is hardly credible that both tuberculosis and Johne's disease could have
been simultaneously present in every goat examined.
SUMMARY
A natural outbreak of paratuberculosis in goats has been described The
history of the farm and the herd point to the probability that these animals
acquired infection from infected cattle maintained on the same farm.
REFERENCES
Ayyar, V. Krishnamurti (1929). Proc. Indian. Sci. Cong., Madras
Cooper, H. and Srinivasan, K. K. (1931). Indian J. Vet. Sci. & Ani. Husb. 1, 215
Dunkin, G. W. and Balfour-Jones, S. E. B. (1935). J. Comp. Path. & Ther. 48, 236
Holmboe, F. V., and Slagsvold, L. (1934). Scand. Vet. Tidskr. 24, 573 [ab. Vet. Bull.
(1935). 5, 690]
Howarth, J. A. (1932). J. Amer. Vet. Med. Assn. 81, 383
Johnstone, D. (1934).Vet. Rec. 13, 1388