H. N. RAY AND J. A. IDNANI 265
at this stage the general condition of the animal gave no indication of its
being so rapidly fatal ; for, experience had shown that B. gibsoni usually
runs a chronic course in pariah dogs, the mortality being 20-30 per cent. Blood
smears from this dog were found on examination to be crowded with small
granular bodies (later on identified as Bartonella canis) in association with a
small number of B. gibsoni. Heart blood was immediately drawn for passage,
and the strain has since been continuously maintained by a series of passages.
Early in 1937 attention was concentrated upon the possibility of separating
the two parasites for studying the clinical symptoms caused by Bartonella
canis alone.
(c) Incubation period.—Experience has shown that the incubation period
of B. gibsoni infection when the parasite is introduced subcutaneously, is
longer than when it is introduced by the intravenous route. Use was made of
this finding in separating a strain of Bartonella canis from a case of mixed in-
fection with B. gibsoni and Bartonella canis. Blood containing both the
parasites was introduced subcutaneously into pariah dogs and within a week
to ten days Bartonella canis appeared in its peripheral circulation ; while
B. gibsoni appeared much later (Table I). Inoculation of the infected blood
by the intravenous route has been found to give rise to the disease within a
week or ten days (Table II). When the subcutaneous method is adopted the
onset of the disease may take up to a fortnight or more before the presence of
the parasites is demonstrable in blood films. Curiously in some cases, the
parasites were not seen until a few days before death although the animals
concerned showed all the characteristic clinical symptoms of the disease such
as excessive anaemic changes in the blood and an elevated temperature.
In acute cases the disease has been observed to end fatally within fifteen
days of the infective inoculation (Table II and Fig. 1—B, B 1 ), while subacute
cases have lingered up to three or four weeks at the most, the mortality still
being cent per cent (Table II and Fig. 1—A, A 1 and C, C 1 ).
(d) Symptoms.—The disease is characterised by the onset of high fever,
rising up to 105°F or more, staring coat, dryness of the nose, constipation
followed by diarrhœa, the stool sometimes being tinged with blood and emitt-
ing a strong offensive smell and being of a deep yellow colour. The mucous
membranes appear very pale and there is discharge from the eyes and nostrils ;
the urine becomes high coloured but no haemoglobin has been observed to be
excreted. There is a progressive impairment of the appetite, and some of
the affected animals have been observed to show a tendency to lick the earth
and devour grass in considerable quantities. In such cases the stomach has,
on post mortem examination, been found to contain nothing except foreign
matter. Marked anaemia has been observed to be very pathognomonic of
Bartonellosis in dogs and a peculiar symptom, that is more often than not,
exhibited is that of panting for breadth without the least excitement. This
appears to be due to an insufficient oxygenation of tissues consequent on the
very heavy destruction of the red blood cells which is usually brought about.
In severe cases the temperature drops by crisis to subnormal, leaving the
affected animal comatose for a couple of days before death supervenes.
(e) Blood changes.—Haematological studies upon a number of healthy
animals were carried out, and then the animals that were to be subjected to
experimentation with Bartonella canis, were thoroughly tested for any deviation