168 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, II
This fact caused the author to decide upon the publication of the results which he obtained at
Onderstepoort in 1925 and 1926 with a new drug which he calls " Piroblue ". The experiments
carried out in the Sandoz laboratories by Muller have shown that the parasiticidal action of stains
such as trypanblue and others can be greatly increased if they are combined in an appropriate form
with the bile acids. This combination can be effected without producing any proportional increase
in their toxicity.
The bile acids and their salts possess no parasiticidal power of their own, but their association
with pure trypanblue renders it possible to reduce the dose of the drug to a point at which toxicity
does not come into consideration at all. Not only so, the parasiticidal action is actually increased.
According to Stoll, the explanation of this effect is probably as follows : Bile acids exert a
profound effect upon the surface tension of liquids containing them. This fact is made use of
commercially in dyeing, and this property enables drugs combined with them to come into closer
contact with parasites.
Two compounds, which are called T18 and T19 were used for experiment. These were composed
of the pure dye and sodium cholate in different proportions. These compounds possessed similar
properties, and it was decided to make one intermediate in composition between these for commercial
application.
The toxicity of " Piroblue " was tested upon mice, but, in spite of the use of a large series of
animals (nearly 100) the results were, for some unknown reasons, discordant.
A series of guinea-pigs was placed under test by intravenous injection. In the majority of
cases a 5 per cent. solution was used, and doses were graduated so as to give 0.1 g. per kg.
upwards. In this series concordant results were obtained, and the toxic dose by intravenous injec-
tion was found to be 0.19 g. per kg.
Full details are given of twelve observations carried out on pure-bred Polled Angus cattle,
five upon African native bred animals obtained from areas free from piroplasmosis, and five upon
horses. Four of the latter were animals undergoing hyperimmunization against horse sickness, the
other a sporadic case. One of the animals was infected with P. caballi, and the other four with
Nuttallia equi. The whole of the seventeen bovines used were infected artificially with
P.bigeminum. Of the twelve Scotch animals six developed haemoglobinuria as did also two of the
African cattle. The blood used was therefore of considerable virulence. The majority of animals
also developed high fever.
Both compounds T18 and T19 were used, in 1 and 2 per cent. solutions, and doses of 100 c.c.
for adults and 50 c.c. for calves were given intravenously. In no case was any evidence of shock
observed. One of the African cattle was given 50 c.c. of 4 per cent. solution of Tl8 without
producing trouble of any kind.
In every case the temperature promptly fell and parasites disappeared from the circulation
within 24 hours, and there was a rapid and surprising improvement in condition. In one case
death occurred, but the calf in question should not have been put under treatment, as it was suffering
from a paratyphoid infection.
T18 and T19 do not produce complete sterilization as is shown by the fact that in eight in-
stances parasites reappeared in the blood in small numbers some days after their first disappearance.
This is not an undesirable result, because premunization against piroplasmosis depends upon the
persistence of the parasite in the blood. The new drug is suitable therefore for use in the premuni¬