70
Treatment of Equine Strongylosis
DISCUSSION
After doses ranging from 30 to 100 gm. the
first two egg-counts were negligible, except in
a very few cases. In the third count, on the other
hand, a slight rise was found in the majority of
cases. This figure however, is very small in
comparison with the count before dosing and is no
more than might be expected in view of the lapse
of time between the times of dosing and the third
count. The increase may be explained by the
maturing of larvae which were in the tissues at
the time of dosing, and which had returned to the
lumen of the gut in the interval.
Doses of less than 30 gm. however, did not
produce comparable results, although a notable
reduction in the egg-count was recorded, for the
25 gm. group of approximately 80 per cent,
and for the 20 gm. group of 40 per cent. In
these two groups the second and third egg-counts
show a rapid increase, and it would seem that
while the drug did not kill all the worms, neverthe-
less it affected the egg-laying activities of the
female, for a period of nearly three weeks.
On the evidence set forth in the above table
the minimum effective dose is considered to be
approximately 30 gm.
Only 11 horses of the total of 95 treated, har-
boured Parascaris equorum, and infestations were
light in all cases. No definite conclusions can
therefore be drawn from these observations con-
cerning the value of the drug against this parasite,
and although the egg-counts from six of the
animals were negative after treatment, the other
results were erratic.
CONCLUSIONS
(1) It would appear from the results given in the
above tables of egg-counts and from the improve-
ments observed in the general condition of the
animals treated that phenothiazine has distinct
merits as an anthelmintic for strongyles in horses,
(2) The average weight of the horses treated in
the above experiment was approximately 1,000
lb., and the effective minimum dose was 30
gm. This represents 1 gm. of phenothiazine
per 33 lb. of body weight.
(3) In view of the fact that phenothiazine may
be given in the feed of the horse with little previous
preparation of the animal it has obvious advant-
ages over drugs requiring long preliminary fasting
and more elaborate methods of administration.
(4) No evidence was obtained of any untoward
reactions, and although slight malaise was observed
in two or three animals, this may have been due to
individual idiosyncrasy.
(5) The drug has the additional value that it
does not interfere with the normal working of the
horse.
(6) The foregoing conclusions suggest that
regular periodic dosing with phenothiazine might
provide a safe and easy method for the control,
if not the complete eradication of strongyles in
horses.
ACKNOWLEDGEMENTS
We desire to express our thanks to Lieut.-Col.
C. G. Darley, D.S.O., Commanding Officer, 3rd
horse Cavalry Training Regiment, and to Major
D. A. Gillmor, R.A.V.C., for the facilities to carry
out this investigation.
TREATMENT OF EQUINE STRONGYLOSIS BY PHENOTHIAZINE
By R. H. KNOWLES, MAJOR R.A.V.C., and A. V. FRANKLIN, MAJOR R.A.V.C.,
R. A. V. C. Laboratory, Aldershot
(Reprinted from the Veterinary Record, Vol. 52, No. 36, September 7, 1940)
AT the suggestion of E. L. Taylor, D.V.Sc.
D.V.H., M.R.C.V.S., Senior Research Officer
of the Laboratory of the Ministry of Agriculture,
and Fisheries, Weybridge, it was decided to carry
out trials at the Royal Army Veterinary Corps
Laboratory to test the efficacy of the anthelmintic
drug thiodiphenylamine, also known as pheno-
thiazine, for the treatment of strongylosis in
horses.
This drug has proved very effective against
stomach worms in sheep and would appear to
exert more effect than any preparation previously
tried for the removal of worms from the large
intestine of sheep. It was thought, therefore
that phenothiazine might prove an efficient expel-
lant of strongyles from the horse.
Three horses were selected for these observa-
tions :
(1) No. 110. Bay Mare, 7 years old. Rider.
Condition moderate.
(2) No. 47 . Bay Mare, 7 years old. Rider.
Condition moderate.
(3) No. 94313. Black Mare, aged. Rider.
Condition poor.
For the purpose of this trial egg counts of the
faeces were made by Stoll's method before and after
the treatment, and were continued for 21 days
after administration of the drug. The results of
these counts are shown in table on next yage.