March 1955] G. S. RATHORE, P. D. MATHUR AND N. S. SANKARNARAYAN 7
finer wool than the controls. The pasture infestation was also considerably reduced.
In the U. K. [Ministry of Agriculture and Fisheries, 1949] with a much smaller
sheep population than Rajasthan and better pastures, the mortality from worm
infection was estimated at 452,400 yearly by the National Veterinary Medical
Association, London. This loss has been substantially reduced by the widespread
use of phenothiazine.
Krishna Rao [1953] in Madras carried out an extensive survey and control of
haemonchosis by phenothiazine. His findings may be studied for details. The
success attained on the comparatively poor sheep of South India suggests that
similar control in Rajasthan will be followed by outstanding improvements.
Experiments with phenothiazine in Australia [Council of Scientific and Industrial
Research, 1946] proved that small doses showed progressive increase in efficiency
against O. columbianum. The largest dose 0.5-1.0 gm. used daily eliminated H.
contortus.
In a recent demonstration by the University of Liverpool Department of Veteri-
nary Medicine a five-month old lamb, showing a faecal count of 46,000/gm. (H.
contortus), was treated with 15 gm. of phenothiazine and destroyed after five days.
Not a single worm was found in the abomasum on post mortem examination.
Franklin, et al., (loc. cit.) state that Trichostrongylus species may be specifically
attacked by tetrachloroethylene medication, but that the degree of control exercised
on this parasite by small and regular routine dosage with phenothiazine for the
more dangerous H. contortus and O. columbianum ensures that it remains pathologi-
cally insignificant. The Ministry of Agriculture, England [1949], also recommends
the use of phenothiazine for periodical dosing of sheep and lambs as a curative and
preventive measure against helminths. Edwards [1948] studied phenothiazine,
its chemical structure, mode of action and excretion, and the effects of administra-
tion. He recommended it as the most efficient veterinary anthelmintic for nematode
infestation. Rogers [1948] studied the action of phenothiazine on helminths and
found that the drug appeared to effect a breakdown of the nematode glycogen.
Gordon [1949] in his paper read at the 14th International Veterinary Congress
discussed the comparative efficiencies of different anthelmintics and concluded that
phenothiazine has such a wide range of action that a diagnosis of the type of hel-
minth present was not necessary. He had already reported in 1945 that since it is
effective irrespective of destination in the digestive tract when swallowed, it can be
used against any helminth, even O. columbianum. Copper sulphate has a very limi-
ted efficiency only if swallowed into the abomasum. This depends on the closure of
the oesophageal groove which is known to be very irregular. Sheep in which this
closure fails remain infested and readily re-infest pastures. Even when closure is
complete Gordon and his co-workers have shown that at least 40 per cent of nema-
todes escape the action of copper sulphate.
An additional and most important aspect of helminth control by phenothiazine
is the inhibition of ova production by worms in the intestine when exposed to routine
dosage. Not only is ovulation greatly depressed but even the ova passed in the
droppings are sterile and do not hatch out to re-infest pastures. Copper sulphate
(with or without nicotine) has no such action.