E. L. TAYLOR AND K. M.
SANDERSON
145
Fifty-three goats were used for this experiment; 25 received one dose of
phenothiazine in capsule form, varying between 10 grammes and 30 grammes
according to the size of the goat, and 28 were kept as controls.
During the three weeks observational period the egg count among the
25 treated goats was reduced from an average of 5,080 to an average of 533,
the egg count among the 28 controls falling from an average of 6,696 to 3,808
during the same period.
Several of the goats showed signs of intoxication for three or four days
after the administration of these doses ; they refused all food, looked dull, and
were often seen to stand motionless in a corner of the stall with their heads
hanging down.
As a result of the various origins of the experimental goats, and the small
number of post-mortem examinations carried out, the results are less conclusive
than they otherwise would have been, but they suggest that the drug acted
particularly powerfully on Ostretagia circumcincta and on Trichostrongylus
axei, less powerfully on worms in general in the small intestine and not at all on
Nematodirus filicollis, Moniezia spp. and Fasciola hepatica.
The post-mortem results also suggest the 10 gramme dose to have been
less efficient than the 20 and 30 gramme doses.
THE EFFECT OF SMALL DOSES IN GOATS.
Experiment No. 9.—In this experiment eight goats received gradually
increasing doses of phenothiazine at intervals of four days, the doses ranging
from 0.5 gramme to 12 grammes. The data which were collected are shown in
Table II and indicate that doses up to l½ grammes are without effect; a dose
of 4 grammes appears to have had some effect, 6 grammes had a decided effect,
and the 8 gramme dose appears to have been just as effective as the 12 gramme
dose given later. In one or two instances, however, the small doses failed to
expel a considerable number of worms, notably in goat 428. These results
conform with those of experiment 8 and it may be concluded that doses of less
than 20 grammes, although effective, cannot be relied upon to produce the
maximum anthelmintic action.
TOLERANCE OF GOATS.—In view of the signs of toxic action seen in several
of the treated goats a series of trials was carried out in order to assess the toxic
dose. In the first trial six goat kids were treated with 10, 20, 30, 40, 50 and
60 grammes respectively, of phenothiazine, but without producing any ill
effect. Eight adult goats were next treated with 50, 60, 70, 80, 90, 100, 110
and 120 grammes respectively, but again without producing any ill effect.
Only three days later when it became clear that there was a negative
result from the previous administration a dose of 400 grammes was given to the
goat that had previously received 80 grammes, but even this produced no
noticeable effect whatever.
SUMMARY OF RESULTS IN GOATS.—Our observations suggest that at
certain times goats may be less tolerant of phenothiazine than are sheep, but
even at those times are good subjects for anthelmintic treatment with this
drug. At other times they are able to withstand enormous doses, similar to
sheep. Doses varying between 10 and 30 grammes reduced the egg count to
one-tenth of what it was before treatment was carried out. A dose of 6
grammes reduced the infestation very considerably and an 8 gramme dose
appeared to be in no way inferior to a 12 gramme dose.