264
Bartonellosis in Dogs
early stage in which the filamentous and granular forms appear to possess
zones similar to an undulating membrane. According to his statement it is
these extensions which represent the ' violin bow ' described by Kikuth and
the coccoid forms are produced by the fragmentation of the filamentous forms.
The parasites are either found on the surface or in the body of the red
blood cell and in this respect our observations are quite in agreement with
those of Regendanz and Reichenow (loc. cit.) and others.
According to our observations the coccoid forms are the earliest to appear
either on the surface or inside the erythrocytes (Plate XVI fig. 2, a, b). For the
first few days after the appearance of the parasite in the blood these forms
usually occurred singly, but as the disease advanced, their number was greatly
increased. When they appeared on the surface of the corpuscle, they were
found to be arranged in a row on the boundry wall of the cell ; when in the
cell they appeared like small dots grouped together in a row of two, four or
more coccoids. At this stage they measured 0.5µ or slightly less in diameter.
On careful examination a single coccoid form before division is found to elon-
gate into a bacillary form and has a deeply staining chromatinic structure
along one of its edges (Plate XVI, fig. 2 c). Later on by a constriction in the
middle two coccoid-like bodies are formed (Plate XVI, fig. 2 d). In this way
by a repeated fission the length of the coccoid chain is increased, each chain
containing four to twelve or more coccoid-like bodies.
Some of the coccoid forms also show a ring phase and in this condition
a chromatinic dot is very prominent at one end of the ring. Coccoids in a
chain also assume a ring phase ; two rings at two ends of the chain are the
smallest, one in the centre is the largest in diameter, while the intermediate
ones show varying gradations in size. These are the forms which have been
given the name of ' violin bow ' by Kikuth (Plate XVI, fig. 2 e). These rings are
sometimes seen to separate from each other and to divide in the usual manner,
that is, the chromatinic dot becomes elongated and subsequently by a constric-
tion in the middle coccoid-like bodies are formed. When more than one chain
are present in a corpuscle, their arrangement is variable. The most usual type
of arrangement that we have encountered in our preparations is y-shaped
(Plate XVI, fig. 2 f). In acute cases the coccoid and bacillary forms are also
found free in the plasma (Plate XVI, fig. 2 g). The parasitised corpuscles in
acute cases appear to stick to each other and consequently in dry film prepa-
rations they mostly appear in groups (Plate XVI, fig. 1 and fig. 2 h).
Smears made from the various internal organs revealed the presence of
this organism and the parasite manifested the same relation to the blood
corpuscle as in the peripheral blood. But a feature worthy of note was that
the spleen smears never showed the parasite, although this organ was in most
cases, hypertrophied during the course of the disease.
(b) Course of the disease.—The dog in which the parasites were observed
for the first time in November 1934 had been initially subinoculated sub-
cutaneously with B. gibsoni infected blood for maintenance of the strain for
experimental purposes, and the parasites (B. gibsoni) appeared in the blood
on the thirteenth day after the infective inoculation and continued to be
rpesent during the following fortnight. On the fifteenth day the animal
was suddenly found gasping for breath and in a state of collapse. Its tem-
perature during the previous few days ranged between 100°F to 102°F and