JOHN
FRANCIS
37
(1) Strangles by the presence of purulent nasal catarrh and the infrequency of lymph-node
swellings and abscess formation.
(2) Brustseuche : in this disease there is a longer incubation period, a more prolonged fever
and usually a red-brown nasal discharge and dull areas in the lungs. At autopsy there is a
serious effusion and a think fibrinous deposit on the pleura which is not seen in respiratory
catarrh.
(3) Influenza, in which there is a marked morning recession of the fever, swelling of the
conjunctiva, œdema of the breast and intestinal catarrh.
Blood taken during the febrile stage produced the disease when inoculated intravenously
into another horse, but both the early serous and the latter 'grey-white' nasal discharge failed
to cause the disease when introduced into the nasal cavity of a horse. Staphylococci were
isolated from the serous nasal discharge, but when once it has assumed the characteristic grey-
white colour gram-negative diplostreptococci were found in about 50 per cent of the exami-
nations. This organism was also isolated from the lungs of four horses which died of broncho-
pneumonia. Bacillus abortus equi was also isolated from one of the cases and staphylococci
from each of the others. A pure culture of the gram-negative diple-streptococcus produced
purulent rhinitis in a horse which had just recovered from a simple virus infection. It was
concluded that this organism, the chief characteristics of which have already been described,
was the most important secondary bacterial invader and that it is probably similar to an
organism isolated by the early workers from cases of brustseuche. Traub [1941] isolated group
'C' and Seeleman [1941] groups 'C' and 'D' streptococci cases of this disease.
Beller and Traub [1941] have made a careful study of respiratory catarrh and in general
their findings agreed with those of Waldmann and Kobe [1936] ; they were, however, unable
to transmit the disease to cattle, ferrets, white mice or pigs, or to propagate it in tissue culture.
Bazely and Battle [1940] have described a disease which rapidly reached epidemic proportion
when numbers of horses were brought into close contact for more than ten days. Various forms
of the disease were observed, but they were grouped under the general term 'respiratory catarrh'.
The authors apparently believed the disease to be due to group C hæmolytic streptococci, but
horses that had passed through an epidemic were immune to subsequent exposure, and it is
quite possible that the condition was similar to the disease described by Waldmann and Kobe
and was primarily due to virue infection. Walker [1935] has described a highly infectious
epidemic of coughing amongst horses in Great Britain.
Pulles [1941] and Rexroth [1941] state that the intravenous injection of 'Thoromangan,'
and iodinethorium-manganese compound, is valuable in the treatment of infectious catarrh.
STRANGLES
The incidence and severity of strangles vary in different parts of the world. It is a serious
disease in the remount depots in India. Arnold [1931] has described the disease in that country
and the methods of prohylaxis and treatment which are employed. Following a primary in-
flammation of the upper respiratory tract an inflammation of the submaxillary lymph-nodes
develops which is not necessarily followed by abscess formation. Pus taken during the earliest
stages of the disease contains no micro-organism.
Wooldridge [1936] mentions that a virus may be the primary cause of strangles, but most
writers appear to accept the view that it is caused by Str. equi. Bazely and Battle [1940]
say ; 'We have found no suggestion of a virus in this disease, and, judging from the regularity
by which Str. equi occurs, none appears to be needed for an adequate ætiology. The fact that
Str. equi but not the other types of group C' streptococci usually associated with equine
disease, can nearly always be isolated from unruptured matured abscesses lends supports to this
view, but the conclusion that Str. equi is the sole cause of strangles cannot easily be accepted
on epidemiological grounds.
It is well known that strangles is a disease of young horses and a life-long immunity is