JOHN
FRANCIS
239
Beller and Traub [ 1941 ] have made a careful
study of respiratory catarrh and in general their
findings agreed with those of Waldmann and Köbe
[ 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 Köbe and was primarily due to
virus 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,' an iodine-
thorium-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 prophylaxis and treatment which are employed.
Following a primary inflammation of the upper
respiratory tract an inflammation of the sub-
maxillary Iymph-nedes develops which is not neces-
sarily 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 support to this
view, but the conclusion that Str. equi is the sole
cause of strangles cannot easily be accepted on
pidemiological grounds.
It is well known that strangles is a disease of
young horses and a life-long immunity is usually
produced. It is notoriously difficult to produce
community
against streptococci and success has not
een attained by the use of streptococcal vaccines
to prevent strangles [ Edwards, 1935 ]. The highly
infectious nature of the disease and the fact that a
strong immunity is usually established suggest that
it is primarily caused by a virus. Bazely and Battle
state that their work was ' conducted in a laboratory
which for the past two and a half years had. concerned
itself exclusively with the study of hæmolytic strepto-
cocci, ' and we can only conclude that no attempt
was made to isolate a virus.
Clinical observation and experiments led Arnold
[ 1933 ] to conclude that strangles is primarily due to
a virus which produces febrile reactions only; a
secondary invasion by streptococci produces all the
recognized manifestations of the disease. The virus
is responsible for the high infectivity and a benign
uncomplicated virus infection is sometimes observed.
On the other hand, sporadic cases may be due to
bacteria only. The virus disease can be produced
by the intra-tracheal inoculation of filtered strangles
pus and this leaves the animal solidly immune
to subsequent infection. A formalized filtrate
produced only slight immunity.
Van Dorssen [1939 ] concluded that ' benign
strangles' was caused solely by Str. equi Richters
[1935] isolated true diphtheria bacilli from the
unopened lymph-nodes and nasal discharge of some
horses affected with malignant strangles ; injections
of these organisms into susceptible horses produced in-
flammation of the nasopharyngeal mucosa and severe
gastro-enteritis. He concludes, however, that neither
these organisms nor streptococci are the primary
cause of strangles, but that it is due to a specific virus.
It has not been possible to find any subsequent
publication of Richters' substantiating this view,
but Beller and Traub [ 1941 ] and Rexroth [ 1941 ]
reached the same conclusion. Law [ 1902 ] noted
that, although horses inoculated with strangles
streptococci developed abscesses, there was no
evidence that the disease produced was contagious,
but taken as a whole the evidence suggesting that a
virus is the primary ætiological agent in this disease
is not perhaps so strong as in those already described.
It has already been mentioned that Krage and
Tiedge [ 1938] isolated S. enteritides, Bact. viscosum
equi and C. diptheria from the organs of horses
affected with malignant strangles.
LESIONS IN NERVOUS AND OTHER TISSUES
The conditions described in this review are usually
accepted as being respiratory diseases, but one cannot
help remarking that the primary virus infection often
exhibits all the features of a generalized disease.
There may be marked impairment of kidney and
liver function, and the predilection of the influenza
virus for the intestine is well known. Traub [ 1941 ]
and Rexroth [ 1941 ] noted pustular and exanthema-
tous lesions during the course of infectious catarrh,
and in an exhaustive clinical study Steffan [ 1941 ]
K