GEOFFREY
LAPAGE
265
The egg counts were reduced immediately, dropping from the region of
1,000 to 1,500 until, three days after the dose, they were negative. They
remained negative until the ninth day after the dose, when the egg counts were
discontinued. After the dose many dead ciliates were found in the faeces.
This suggests that phenothiazine kills ciliates which live, as those of the horse
do, in the caecum and colon, although the introduction of phenothiazine
directly into the rumen contents of a sheep had had no effect on the ciliates
there (as recorded above). This is a detail which supports the view expressed
by other workers that phenothiazine has more effect on parasites which live in
the caecum and colon, a view which suggests that phenothiazine cannot act
immediately, but requires time to undergo some change before its toxic action
on nematodes is exerted.
HORSES DOSED WITH PHENOTHIAZINE POWDER IN BRAN AND TREACLE.—
(1) A longer series of observations was made on a New Forest pony weighing
714 lb., belonging to this Institute. This pony was out at grass throughout the
observations and was given 60 grammes of phenothiazine in bran and treacle.
The phenothiazine powder now available was not being made when this experi-
ment was done, but 60 tablets, each containing 1 gramme of phenothiazine,
were broken up and mixed with the bran and treacle. The egg count showed
only strongyle eggs, and although the egg count was not very high, the mean of
two daily counts ranging from 350 to 1,150, it had become 0 on the third day
after the dose. Egg counts were continued every two or three days and,
although the pony was out at grass, they remained negative until the 41st
day after the dose, when 150 e.p.g. were present. On the 44th day after the
dose 250 e.p.g. were found, and on the 48th day 100 e.p.g. The pony was
therefore then acquiring a slight reinfestation. No toxic effects whatever were
observed in this animal. It grazed on the same pastures until 24-6-40, when
the average of two egg counts was 400. A further infestation was thus being
established then.
(2) Thoroughbred 3 was given 40 grammes of phenothiazine powder, pre-
pared in a similar way, a dose of about 0.2 gramme per lb. body weight, in
bran and treacle with a similar result. The mean of two daily egg counts on
this horse ranged from 150 to 800 for a period of 23 days before the dose. This
horse was kept indoors in a box throughout the observation. The day after
the dose, its mucosae were bronzed, but were practically normal again in four
days and quite normal seven days after the dose. The blood of this horse was
examined spectroscopically on the first and second days after the dose, but
nothing abnormal was found in it. No toxic effects were observed. The egg
count became negative on the second day after the dose and remained so until
the eleventh day after the dose when the experiment was discontinued.
THOROUGHBREDS GIVEN PHENOTHIAZINE POWDER IN WATER BY STOMACH
TUBE TO TEST ITS TOXICITY
Thoroughbred 2.—This mare, two years old, 952 lb. in weight, was given
500 grammes of phenothiazine powder obtained by crushing up in water tablets
each of which contained 1 gramme of phenothiazine. The suspension was given
through a stomach tube. The object of this very large dose, amounting to