NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
TREATMENT OF DISEASES CAUSED BY WORMS 37
judgment if he is to be trusted with the more or less poisonous drugs
which constitute our present armamentarium of anthelmintics. He
can be taught, or could be if we had suitable teachers, a sound know-
ledge of the other factors involved in anthelmintic medication. He
cannot be taught to be a person of sound judgment, if he is intrinsically
a person of unsound judgment ; the poor thinker will continue to be
a dangerous performer with potent drugs, and will continue to dis-
credit excellent drugs by obtaining bad results as a result of bad
judgment.
(2) The patient must always be considered as to status praesens in connection
with the other factors, and especially in regard to conditions constitut-
ing contraindications for treatment. Failure to consider contraindica-
tions is altogether too common, and is a prolific source of fatalities.
(3) The parasite must be known definitely and its habits, location, and life
history taken into consideration. A knowledge of these facts leads to
sound procedures, and affords an intelligent explanation for certain
failures.
(4) The parasiticide (the anthelmintic) must be selected not only with reference
to its known action on the worms to be removed, but also with
reference to its effects on the patient. These drugs are potent and
poisonous, they exert a certain amount of unfavourable effect on the
patient and the practitioner must select his drug and his dosage with
reference to both of these things.
(5) The purgative is usually the most important factor in connection with the
procedure of safety: It must be selected with reference to its known
action in connection with any anthelmintic, since some purgatives are
unsuitable with certain anthelmintics, and either afford inadequate
protection to the patient or diminish the efficacy of the anthelmintic.
Purgatives should be given in adequate amounts, as small amounts
are as bad as, or worse than, none. The time and mode of adminis-
tering the purgative are also important.
(6) Prophylaxis rounds out the job of treatment. The practitioner has not
fulfilled his duty to his client until he has not only aided him in his
trouble, but also told him why he was in trouble, and how to avoid
similar trouble in the future if the state of our knowledge affords such
information. The veterinarian who treats a herd of swine in a hot
lot, and leaves the swine to pick up millions of ascarid eggs from the
ascarids removed and left there, has an inadequate idea as to his duty
to his client.
38 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, I
II. The Patient as a Factor. The important thing in connection with the
patient is the matter of contraindications (1) for anthelmintic treatment, (2) for
certain drugs, or (3) for full doses. These may be briefly stated as follows :—
(1) Contraindications for treatment of any sort, as a rule, include extreme
weakness, emaciation, and starvation, or febrile conditions, or marked toxic condi-
tions, or extreme youth or age, or pregnancy. Whether these general contraindica-
tions hold in a given case is a matter for the practitioner to decide in
accordance with his knowledge and judgment. Weak, emaciated, and starved
patients will usually benefit by a sound feeding régime to put them in better
condition to tolerate treatment, but in cases where weakness and emaciation
obviously follow from an insupportable worm burden, good judgment may indicate
the administration of diminished doses of an anthelmintic suited to the weakened
condition of the patient, with the idea of gradually diminishing the worm
burden and enabling the patient to tolerate in time a full therapeutic dose of an
anthelmintic.
Febrile conditions, usually associated with bacterial infections, should be
treated first and the worms removed after the patient has recovered from the febrile
conditions, as a rule ; but the practitioner will have reason to believe, in some
cases, that relief from the febrile condition can be more certainly secured by the
preliminary removal of part or all of the worm burden. It is impossible to formulate
precise rules on this subject, as every case will be an individual case to be decided
by the practitioner.
Marked toxic conditions constitute a contraindication for the additional insult
of the more or less poisonous drugs constituting our anthelmintics, as the com-
bined burden may be insupportable. However, there will be times when the
practitioner who is well informed as to drug action will elect to use. a drug which
will impose an injury on an organ not especially affected by the toxic conditions
already present, and thus take the worm burden out of the general picture and give
the patient this advantage in throwing off the existing toxic condition.
In general, very young or very old animals do not tolerate antheimintics very
well. Very young animals should be surrounded with conditions tending to prevent
further infestation and allowed to attain more age resistance before treatment, and
very old animals should be regarded as bad risks and allowed to live out their lives
with their worms, or be humanely destroyed.
Pregnancy is a general contraindication for anthelmintic treatment, although
certain drugs appear to be safe for use in this condition. However, one should try
to clear out worm infestations from females before they are bred, not only to avoid
any necessity for treatment during pregnancy, but to put the animals in better
TREATMENT OF DISEASES CAUSED BY WORMS 39
condition during this critical time, and allow them and the fœtus to benefit accord-
ingly. It is probable that the bad results in the way of abortions and miscarriages
in connection with anthelmintic treatments are associated at times with the use
of drastic purgatives rather than the action of the anthelmintic.
(2) Contraindications for individual drugs are of many sorts, and follow from
the particular action of the drug in question on the host to be treated. In some
instances we have alternative drugs having different actions on the host, and one
of these may be indicated for use in connection with contraindications for another
drug or other drugs. One might say in general that one avoids gastro-intestinal
irritants in the presence of gastro-enteritis, chlorinated hydro-carbons causing
hepatic necrosis in the presence of serious liver injury, drugs unfavourably affecting
the nervous system in the presence of epileptic conditions, etc. All these rules are
subject to modification, as we may at times have such results as improvement in
cases of inadequate liver functioning after the administration of a drug which
injures the liver but stimulates a chronic indolent trouble into an acute condition
going on to repair and recovery.
(3) Contraindications for full doses are frequently encountered. In this connec-
tion one should consider the apparent age, rather than the chronological age, of
an animal, in judging the dose which will be tolerated, and base the dose on size,
general condition, and other things. Gross helminthiasis in young animals is a
condition which may call for diminished doses and repeated treatments, rather
than one full therapeutic dose. Occasionally the killing of large masses of ascarids
may cause intestinal obstruction from clumps of worms in weak animals with an
atonic intestine too feeble to remove these masses. The selection of the dose
is emphatically a matter calling for sound information and good judgment on the
part of the practitioner, and no specific instructions can take the place of such
information and judgment.
III. The Anthelmintic as a Factor. The older books define an anthelmintic as
a relatively insoluble drug which remains for the most part in the digestive tract,
poisons the worms, and then is swept out by a purgative before any considerable
amount of absorption can occur, the patient being thus little affected. This defines
a somewhat ideal sort of anthelmintic for worms in the digestive tract, but does
not represent our present concept of anthelmintics or the actual facts. Anthelmin-
tics at present include drugs used to destroy worms in places outside of the diges-
tive tract, where absorption of the drug from the digestive tract is essential or
where the drug is actually given intravenously or in some other manner which
precludes the idea that it will not be absorbed and have systemic effects. More-
over, the anthelmintics in use for removing worms from the digestive tract are
40 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, I
known to be absorbed to a large extent. Most of the thymol administered and
practically all of the carbon tetrachloride in a therapeutic dose are absorbed,
although both are relatively insoluble, and carbon tetrachloride is more insoluble
in water than is thymol.
In general, anthelmintics are rather selective in their action. One may remove
ascarids, but not hookworms or tapeworms ; another may remove tapeworms but
not nematodes ; another may remove hookworms but not ascarids. This fact
probably follows in part from the habits, physiology, and structure of the worms.
Some anthelmintics have a more restricted range of action than others, but we
have as yet no one dependable anthelmintic for all sorts of worms. Such worms
as whipworms, situated in the cæcum, and probably rarely subjected to the in-
jurious effects of substances taken by mouth, appear to be highly susceptible to
numerous anthelmintics if the drugs come in contact with the worms, and the
difficulty here appears to be to find anthelmintics which for one reason or another
will get to the cæcum in amounts sufficient to kill these worms.
The form in which an anthelmintic is administered will often affect the result.
Thus, fluid extracts may contain active anthelmintics, but the alcohol present may
lead to rapid absorption of the anthelmintic in the stomach and upper intestine
with the production of systemic effects and the lessening of the anthelmintic effect.
IV. Procedures in Anthelmintic Medication. The procedure in anthelmintic
medication may be as important as the selection of the drug. Thus, santonin
develops its action against ascarids much more effectively when it is given in small
doses repeated daily for a period of time than when it is given in one large dose.
Whipworms require the administration of bulky doses of a suitable drug, part of
which is likely to enter the cæcum, or else the repeated administration of small
doses of a suitable, non-irritant drug over a period of time in order to increase the
likelihood that some part of these doses will enter the cæcum. Preliminary
purgation, preferably with salts, appears to be important in treatments for the
removal of tapeworms, presumably because it is necessary to clear the mucus
away from the head of the worm if complete removal is to be obtained. The
use of the doudenal tube has been recommended for the administration of anthel-
mintics for the removal of tapeworms in order to avoid gastric absorption of the
drug, a point which deserves further study.
Fasting is a matter of importance. It is not true, as was at one time
supposed, that fasting starves the worms and leads them to ingest an anthelmin-
tic carried in a tempting vehicle, such as milk, as we know that ascarids may
be kept alive for 26 days in such an innutritious medium as Kronecker's solution.
However, tasting is important in preventing the dilution of the drug in food
TREATMENT OF DISEASES CAUSED BY WORMS 41
masses, in preventing the escape of worms protected from the anthelmintic by
food masses, and in preventing the bad effects often noted when anthelmintics
are administered on a full stomach with the digestive processes active. Our
reasons for fasting are largely theoretical, but practice supports the general
contention, and experimental evidence shows definitely that anthelmintics
administered in food are usually infective or require administration over long
periods to compare in efficacy with drugs given in therapeutic doses to fasting
animals.
The length of the preliminary fast necessary for effective anthelmintic action
varies with different animals. In the cases of man and the dog and cat, fasting
overnight appears to be sufficient and better than a longer period. In these
animals the simple stomach empties rather promptly, and prolonged fasting puts
the patient in an abnormal condition in which the patient's discomfort and other
bad effects of the anthelmintic are increased. Swine should be fasted at least
24 hours. Horses should be fasted 12 to 24 hours before treatments for stomach
worms, bots and ascarids, but fasted 36 hours before treatments for strongyles
in the large intestine. It is hopeless to try to empty the rumen of ruminants,
and the treatments which have been found effective against worms in these animals
are usually effective after an overnight fast or regardless of fasting. An interesting
development in this connection is the finding of Minot and Culter that carbon
tetrachloride may induce guanidine retention, and as a practical point it might
be noted that quite generally deaths in sheep from the small amount of carbon
tetrachloride, 1 c. c., used in treatments for liver flukes, have followed in the
United States only in cases where sheep were on feed other than pasture grass
alone, and not where they were on pasture. As a practical measure for avoiding
these deaths, Dr. Robert Jay, of the Zoological Division, who is in charge of liver-
fluke-control work in California, has advocated putting sheep back on a low-
maintenance diet on pasture for a few days before treating with carbon tetra-
chloride.
After treatment, in the cases of man, dogs and cats, food should be withheld
for three or four hours, or until the bowels move. Swine should not be fed until
after a longer period, perhaps six hours. Information appears to be lacking as
to the correct procedure for horses and ruminants, but at this time we are inclined
to think that feed should be withheld for three or four hours after treatment.
This may not be necessary with ruminants. With most animals the drug should
be given time to leave the stomach before food is allowed.
V. Purgation. Purgation is protective ; in fact it is the most important of
the routine procedures in connection with the safety and comfort of the patient.
42 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, I
In the treatment of human patients, from whom we can best obtain information
as to certain symptoms caused by anthelmintic medication practically all the
anthelmintics administered by mouth produce, in a large proportion of cases,
headache, dizziness, or nausea, or any two or all of these symptoms, the nausea
being associated both with the anthelmintic and the purgative. These symptoms
quite generally abate or disappear when the bowels move. In human medicine
it appears to be advisable to follow this procedure : The patient should report
to the physician or nurse four hours after treatment, and if the bowels have not
moved, another dose of a fast-acting purgative, such as salts, should be given, and
the patient told to report again in four hours ; if the bowels have not moved eight
hours after treatment, purgatives, enemas, and other measures should be used to
obtain purgation. Failure to obtain purgation may lead to serious consequences.
In veterinary medicine no standardised procedures have been developed in
connection with ensuring purgation, but the veterinarian should keep in mind
that purgation is highly important, and take the necessary steps to ensure it.
Such drugs as arecoline hydrobromide hypodermically may be of value in cases
of delayed purgation. In this connection, it may be noted that ordinarily it is
unnecessary to resort to preliminary purgation before anthelmintic treatment.
There are, however, certain exceptions. Patients which are constipated should
be given a purgative the night before treatment ; otherwise, it may be difficult to
secure purgation promptly after treatment. Preliminary purgation is also
necessary or desirable in connection with treatments for tapeworm infestations,
as the use of such drugs as salts apparently serves to clear the mucus away from
the tapeworm head and thus expose it to the action of the anthelmintic.
The choice of a purgative and the procedure in administering it must be based
on the ascertained action of a given purgative in connection with a given anthel-
mintic. Experimental evidence indicates that castor oil is very satisfactory when
given simultaneously with chenopodium in ascariasis, the chenopodium displaying
a high efficacy and the castor oil being highly protective. Critical evidence
indicates that castor oil apparently does not increase the absorption of such drugs
as chenopodium and male fern, and that in adequate doses it will protect patients
against the effects of even lethal doses of these drugs. On the other hand, castor
oil lowers the efficacy of carbon tetrachloride against hookworms. Why purgatives
protect the patient as much as they do is not clear. It does not appear to be
true that they sweep from the digestive tract any considerable amount of un-
absorbed drug. Theoretically, what they do is to distribute the insult of the
anthelmintic over a larger area of mucosa and over a longer time period by carry-
ing the anthelmintic farther along the digestive tract and retarding absorption.
TREATMENT OF DISEASES CAUSED BY WORMS 43
Castor oil should be used, as a rule, only in those cases in which it can be given
with the anthelmintic. If the purgative is to be given an hour or two after the
anthelmintic, it is advisable to use the fast-acting purgatives, such as salts.
Macht has shown that salts, by virtue of the well-known salt action, lessen
or inhibit the absorption of drugs given with them. They are, therefore, contra-
indicated for use with drugs from which a systemic effect is desired. On the other
hand, the salt action is of value in connection with anthelmintics for removing
worms from the digestive tract proper, since systemic action is not desired from
these drugs, and it is desired to confine their action to one exerted within the
lumen of the digestive canal. In using salts, the present tendency is to substitute
sodium sulphate for magnesium sulphate on the ground that sodium is less toxic
than magnesium, and does not have the same antagonistic action with the blood
calcium. Experience in human medicine shows that saturated solutions of salts
produce more nausea and other bad effects than do weaker solutions, and it is
advisable to make a saturated solution and dilute it with twice its bulk of water
for use. Salts are most readily used in veterinary medicine in patients which do
not vomit, or vomit with difficulty, such as ruminants and solipeds. Dogs show a
disposition to vomit after salts, although this tendency can be overcome, and salts
can be used in dog practice.
Liquid petrolatum in some form is often used in connection with anthelmintics,
and may be satisfactory in the treatment of such animals as the horse. Tests
show that it is unsatisfactory in combination with chenopodium in the treatment
of dogs, as it lowers the anthelmintic efficacy and gives inadequate protection
against the effects of the drug on the dog. A more extended study should be
made as to the effect of varying the amount of petrolatum, as this may be a factor
in determining the results. Olive oil is sometimes used in connection with anthel-
mintics, but experience indicates that this is usually bad practice. Olive oil is one
of the substances which remain longest in the stomach, and in combination with
chenopodium there results a decided inflammation of the stomach from the prolonged
irritant action of the chenopodium at this point. There is also a resultant fall in
efficacy due to the absorption of the drug in the stomach.
In veterinary medicine the value of our anthelmintics must be ascertained
by critical testing if we are to have dependable information. In critical testing,
animals are given measured doses of the drugs to be tested, all worms passed for
a suitable period are collected, identified, and counted, and the animals are then
killed, and all worms present post-mortem are collected, identified, and counted.
These two sets of figures give the total numbers of worms of each kind present at the
beginning of the experiment, and one can compute rather accurately the percentage
44 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ I, I
of efficacy of the drug, provided a sufficiently large number of experiment animals
is used.
This method of ascertaining efficacy by critical testing has its limitations.
Worms destroyed in the stomach usually undergo complete digestion, or are
partially digested before passing to the intestine. Further, this method cannot be
depended on to ascertain contraindications for the use of anthelmintics owing to
the limitation in the number of animals which can be used. One may ascertain
much as to toxicity of the drug by using high doses, and one can find some test
animals with such general contraindications as febrile conditions, extreme youth,
etc., but it requires the larger test of clinical experience in various places and at
various times to ascertain possible contraindications of all sorts. Here is a field
of observation to which insufficient attention is paid by the veterinarian in practice.
He keeps too few clinical records, and spends too little time in their analysis, to
furnish the information he might furnish along this line. For this reason the
pharmocologist would have to be depended on for the most part, to ascertain the
effect of a drug on an animal in order to give us a general basis on which to predi-
cate contraindications.
The alternative to critical testing is investigation by the egg-count method,
and this method has decided limitations. Egg-counts do not show male worms,
larval or immature worms, sterile females, or females, in which egg production has
been inhibited temporarily by drug action. Their value is also limited by our limited
knowledge or ignorance of egg ratios for many worms, our inability to distinguish
the eggs of many of the various worm species, variations in egg production and in
character and amount of the fæces, and errors in technic.
In clinical experience combined with laboratory procedures for checking
anthelmintic treatments there are certain things which may be kept in mind in
connection with the appearance of eggs in the fæces after treatment. These eggs
may indicate what they seem to indicate—the complete or partial failure of the
anthelmintic. On the other hand, they may indicate the appearance in the digestive
tract of worms which had been wandering through the tissues or developing in cysts
at the time the treatment was given, especially if the faces are examined several
days after treatment. They may also indicate that worms were inaccessible at the
time of treatment, as would be the case with egg-producing female ascarids in
the bile ducts.
In judging the value of an anthelmintic, one must allow time for the passage
of the dead worms. Dog ascarids may pass for seven days although over 80 per
cent. come away the first 24 hours. An examination of the fæces of dogs for four
days will account for 98 per cent. of the worms passed. Horses may require 17