266
Anthelmintic Action of Phenothiazine
rather more than 0.5 gramme per lb. body weight, was to test the toxicity of
the drug. There were so few eggs in the faeces that this animal was not suit-
able for observation of the anthelmintic efficiency of the drug. On the day
after the dose the animal was off its food and was passing red urine. The
mucosae were bronzed and there were petechial haemorrhages in the vulva
around the vestibule, possibly due to irritation by the urine. On the second
day after the dose, the animal was normal again and remained so until the
fourth day after the dose, when the mucosae were practically normal in colour.
The animal had evidently suffered no serious ill-effects from this large dose.
Forty-nine days after this large dose, a second dose of 500 grammes was
given, also by stomach tube. This time the phenothiazine powder that had
just been introduced by Imperial Chemical Industries was used in water. This
large dose was given in the morning. At 3 P.M. the same day the animal
was uneasy, showed evidence of intestinal discomfort, and would not feed.
The mucosae of its eyes and mouth were already bronzed and the urine thick
and chocolate-coloured. Possibly the intestinal discomfort was due to the
mechanical effects of the bulk of the drug in the stomach, because by the next
morning the animal was feeding well and seemed fairly fit. The mucosae were
still bronzed and the urine red. Blood submitted to Professor Keilin for spec-
troscopic examination showed an increase of about 10 to 12 per cent. of methae-
moglobin which suggested that the phenothiazine had produced some oxida-
tion of the haemoglobin, but the amount of methaemoglobin was not accurately
estimated. No sulphhaemoglobin was present and the blood did not show
any other abnormality. On the following day the methaemoglobin was only
slightly reduced, but by 16-1-40, eight days after the dose, it had practically
all disappeared. In blood, taken two days after the dose, the haemoglobin
index was 83 per cent. and the red cell count 6,037,500, the colour index being
0.7 ; two days later the haemoglobin index was 78 per cent, and the red cell
count 6,818,000, the colour index being 0.58. On the eighth day after the
dose, the haemoglobin index was 81 per cent., and the red cell count 7,000,000
and the colour index 0.578. These figures are within the normal variations
shown by the blood of healthy horses.
The day after the dose, a number of dead strongyles were recovered from
the faeces, some containing eggs, others being flattened and pigmented brown.
These were identified as mature and immature Trichonema spp.
On the second day after the dose, the animal was still listless, but brighter
than the daybefore. Its temperature was 92.2°, and the limbs were cold. It
ate hay, but little else ; the mucosae were still bronzed and the urine red ; in
the afternoon the temperature had risen to 100.2° and a bran mash was refused.
On the third day after the dose the animal was still listless, with a morning
temperature of 100° and an afternoon one of 99.2° and red urine and bronzed
mucosae. Rather more food was taken and the condition was on the whole
better. On the fourth day after the dose the temperature was as for the third
day, the mucosae almost normal, the urine still red and the animal was eating
hay only.
On the fifth day after the dose the morning temperature was 100.6°, the
mucosae about the same, the urine still red, but the animal was much brighter
and was feeding better.