304
'Lahore Canine Fever' and 'Tick Fever' of dogs
forty-seventh day it was numerous, after which it disappeared until the eighty-
ninth day. On the fiftieth day the haemoglobin percentage was 50. Treat-
ment with S. U. P. 36 was commenced on the fifty-sixth day and thus removed
the case from the field of comparative clinical consideration.
Puppy No. 7 (Chart 2) was inoculated subcutaneously with 1 c.c. virulent
blood on 28th March 1934 and treatment with tryparsamide was commenced on
the 21st May 1934. A febrile reaction commenced early in this case, a typical
' swinging ' fever very similar to that seen in a clinical case of ' Lahore Canine
Fever', if somewhat less marked. Pathological cells appeared in the blood
(histiocytes and bi- and tri-lobed leucocytes) on the twenty-fifth day,
when the haemoglobin percentage was 80. P. gibsoni was found scantily on
the thirty-first day and remained till the thirty-fourth day. It did not reappear
till the forty-fourth day and in the interval profound secondary anaemia was
evident with a haemoglobin percentage of 40. Parasites remained present, in
very small numbers from the forty-fourth day until the commencement of
treatment.
Although these experiments were complicated by the presence of a certain
quantity of pariah blood (i.e., immune blood) in the experimental puppies, yet
it will be seen from them that important facts can be deduced in relation to
those known concerning 'Lahore Canine Fever' and these show the close analogy
between the two diseases. Clinically, both are characterised by a ' swinging '
pyrexia. Periodically there is an abatement of fever, when the temperature
may drop to within a normal range, succeeded, usually abruptly, by a sharp
upward rise. In the experimental dogs, this upward trend coincided with the
appearance of P. gibsoni in the circulating blood. (See charts). In Puppy
No. 10, it will be seen, however, that the appearance of the piroplasm coincides
with the remission of fever. In certain authentic cases of ' Lahore Canine
Fever ' which had, owing to the sudden appearance of P. gibsoni, towards the
terminal phase of the disease, to be accepted as originally true P. gibsoni infec-
tions, a similar feature was noted. A most important observation arising from
the clinical examination both of cases of ' Lahore Canine Fever ' and artifi-
cially induced P. gibsoni infection is that, within three to four weeks there is
evidence in the circulating blood of commencing derangement of the haemo¬
poietic system, especially the reticulo-endothelium of the spleen. This is
evidenced by the appearance of histiocytes; and slightly later, by a type of
leucocytosis in which the leucocytes are bi- or tri-lobed (shift to the left).
The origin of this phase may be argued from the post mortem examinations.
It probably depends on an invasion of the leucoblastic tissues on the part of
the erythroblastic in the medullary centres, an invasion probably accompanied
by some degree of toxic change.
The clinical history of Puppy No. 13 enhances the analogy. This case
resembled an authentic case of ' Lahore Canine Fever ' in every detail, even
to the complete absence of P. gibsoni in the circulating blood during the disease
syndrome. The case of Puppy No. 15 was only slightly different. The dis-
ease syndrome was similar to ' Lahore Canine Fever ', but P. gibsoni made its