P. N. NANDA AND GURBAX SINGH 17
abomasum has been considered necessary and an effective method must there-
fore be evolved before an attempt is made to work out a satisfactory chemo-
therapy of gastro-intestinal worms. Ordinarily, all food and water when taken
by bovines pass into the rumen unless, of course, as stated by Smith [1921]
water is taken in excess, when the superfluous quantity may overflow from the
rumen and reticulum to the abomasum. The ability of certain drugs in solu-
tion to pass directly into the abomasum is said to be due to a reflex act in which
the drug is supposed to cause a stimulation of the vagus nerve in the pharynx
with the subsequent closure of the oesophageal groove. As to what extent the
direct passage of the drugs into the abomasum affects their efficiency has
not yet been definitely worked out. Although, Green [1918] and Veglia
[1918] as a result of their studies on the chemotherapy of haemonchosis in
sheep claim that it makes no difference whatever, if the drug employed reaches
the abomasum in concentrated form or in small quantities from rumen ; yet
it has been shown by Monnig [1935] that the efficacy of treatment depends
not only on the drugs used but, to an equal degree, on the route taken by them.
It appears from the work of Green and Veglia (loc. cit) which was undertaken
in connection with the Government wire worm remedy* that the results were
judged by the degree of concentration of arsenic reaching the abomasum.
Since this remedy also contains a large proportion of copper sulphate which
does not seem to have been taken into consideration, the interpretation cannot
refute Monnig's [1935] observations. Other workers, like Ross [1934] and
LeRoux [1932] also consider that the efficiency of copper sulphate against
haemonchosis in sheep is due to the direct passage of this drug into the aboma-
sum. Besides the advantage of enhancing the effectiveness of anthelmintics
against gastro-intestinal worms, the dosing of drugs into the abomasum has
three more points of interest in its favour, i.e.
1. The action of the undiluted drugs is speedy and effective.
2. The dose of the drug can effectively be reduced minimising the
possibility of producing any toxic action.
3. There is less risk of causing tympanitis if volatile compounds are
to be administered.
Thus, it is apparent that a careful study of all the factors connected with
the reflex closure of the oesophageal groove is likely to bring about a great deal
of improvement in the veterinary therapy in general and anthelmintic medica-
tion in particular. A review of the somewhat meagre literature on the subject,
as summarised below, does not give adequate information to enable one to draw
definite conclusions, as in many instances the results claimed are of a conflict-
ing nature.
Wester [1926] was perhaps the first to study the physiology of deglutition
in cattle. He was able to prove that sodium salts were effective in causing the
closure of the oesophageal groove in cattle and that the reflex action was more
readily stimulated in thirsty animals.
Daubney [1930] concluded that drugs administered to sheep as a drench
were retained in bulk in the rumen and did not reach the abomasum and small
intestine for some considerable time after digestion. He also noted that
* Government wire worm remedy issued by the Director of Veterinary Services in
the Union of South Africa for the control of haemonchosis of sheep.