E. L. TAYLOR AND K. M.
SANDERSON
143
Experiment No. 6.—This observation, carried out by K. D. Downham,
concerned 20 healthy lambs, all born in March, and picked out from a well-
managed flock that had been periodically dosed with copper sulphate and re-
ceived frequent changes of pasture throughout the previous summer. The
lambs were divided into two equal groups the members of one of which received
a dose of 15 grammes of phenothiazine on December 6th.
A second weighing carried out three weeks later showed an average in-
crease of 0.7 per head among the group of dosed lambs in excess of the increase
among the controls.
Experiment No. 7.—Another collaborator, J. W. Ironside of the Midland
Agricultural College, carried out a similar observation on ten healthy lambs,
previously treated with copper sulphate and nicotine sulphate.
Results also showed a slight increase of weight in favour of the treated
group which during four weeks gained an average of 10.4 lb. as compared with
9.8 lb. in the controls.
EXPERIMENTS WITH SMALL DOSES.—It was felt that the large size of the
dose and the bulky nature of the drug threatened to be the most powerful
factor operating against its general use in sheep and we, therefore, carried out
a few trials to ascertain whether it might not be possible to secure adequate
anthelmintic action with a much smaller dose. Results of the trials carried
out on eight sheep are shown in Table VI and indicate that whereas doses of less
than 3 grammes had no action, those of 3 grammes (0.08 grammes per kg.
body weight) and over, produced a marked effect.*
Some further evidence of the minimum effective dosage is given in Table
IX, which suggests that amounts as small as 1.5 grammes and 1.75 grammes
had some effect.
DAILY DOSES OF PHENOTHIAZINE MIXED WITH THE FOOD.—Doses of 2
grammes, 5 grammes and 10 grammes were tried in three pairs of sheep, the
phenothiazine being given in powder form mixed with the food. The results,
which are given in Table VII, show considerable effect even for the 2 gramme
doses, the 10 gramme dose, however, producing the result more rapidly.
The sheep receiving the 10 gramme doses did not eat their medicated
food at all readily but those on the smallest dose took it well; and suffered no
ill effect whatsoever ; the two sheep receiving 10 grammes daily, however,
began to show signs of intoxication after the first week, dullness and inappe-
tence being the principal symptoms, and on the thirteenth day one of them
died, showing diarrhoeic symptoms for a few hours beforehand.
TOLERANCE OF SHEEP.—Apart from the daily dosing of 10 grammes no
evidence of the slightest toxic effect had been observed in any of the thera-
peutic treatments of sheep ; in an endeavour to obtain some idea of the toxic
dose, therefore, four lambs weighing between 86 and 89 lb. received 40 grammes,
80 gramme's, 200 grammes and 400 grammes of phenothiazine respectively,
but without any signs of intoxication being produced.
The absence of result from the top dose seemed so surprising that it was
repeated in another lamb of the same weight, but again produced no ill effect
whatever.
*It is possible that the dose of 1 gramme given to these sheep four days previously
may have helped to bring about the observed result. This possibility also applies to the
results obtained in the goats, which had also received small doses two or three days
previously.