Veterinary Science Mimeograph July, 1954
Series No. 55-2
UNIVERSITY OF FLOIRDA
AGRICULTURAL EXPERIMENT STATIONS
WILLIARD M. FIFIELD, Director
INTERNAL PARASITES OF CATTLE
Leonard E. Swanson, Walter R. Dennis and William M. Stone, Jr.
I. General Introduction
A. Parasitology is the science that deals with parasitism.
1. A parasite is an animal that lives upon or within another
living organism at whose expense it obtains nourishment and
protection without giving anything in return for this rela-
2. Parasitism is the relationship between the host and parasite.
3. Helminth is a defined term for worms.
4. Helminthology is the study of worms.
B. All animals are parasitized with one form or another of these
C. Wild animals are especially heavily parasitized and quite often
serve as reservoirs of infection for domestic animals.
II. Relationship of Parasites
A. Symbiosis The living together of two dissimilar organisms to
the advantage of both.
1. Mutualism is a form of symbiosis in which both symbionts are,
in more or less measure, benefited by the association.
2. Commensalism is a form of symbiosis in which-one symbiont is
benefited, but its co-symbiont is neither benefited nor harmed.
3. Helotism is a form of symbiosis in which one organism enslaves
B. In summary, a symbiont receiving the benefit is the parasite and
the one receiving the damage is the host.
III. Zobparasites are parasites which belong to the animal kingdom.
IV. Ectoparasites are those that are parasitic to the surface of the body.
V. Endoparasites are parasites which enter the body of the host, in-
habiting the alimentary canal, liver, lungs, blood and other tissue.
VI. The influence of parasites upon the host depends upon the number of
parasites present, location, the nature of their food, environmental
conditions, and age of the host. The effects of parasites on the
host also depend on the balance of minerals, vitamins and proper food
VII. Parasites Injure the Host
A. Through mechanical injury such as biting and migration.
B. Through obstruction as in the case of a mass infection of lungworms
blocking the respiratory tract.
C. By injection of toxins such as occur in extreme hookworm infections.
D. Tissue feeding such as maggots.
E. Anaphylactic reaction extreme sensitivity to touch of ascarids.
VIII. Internal parasites of cattle fall into the following phylum and class:
A. Phylu Platyhelminthes
1. Class Trematoda
a. Example: liver fluke
2. Class Cestoda
a. Example: tapeworms
B. Phylum Nemathelminthes
1. Class Nematoda
a. Example: all roundworms
IX. Internal parasites of cattle listed according to their location in
the body are:
A. Bronchial tubes of the lungs
a. Dictyocaulus viviparus
1. Liver flukes
a. Fasciola hepatica
b. Fascioloides magna
c. Fasciola aegyptiaca
C. Rumen (Paunch)
1. Rumen flukes
a. Paramphistomum cervi
b. Cotylophoron cotylophorum
D. Abomasum (True Stomach)
a. Haemonchus contortus
2. Lesser Stomach worm
a. Ostertagia ostertagi
3. Bankrupt worm
a. Trichostrongylus axei
E. Small Intestine
1. Threadworms (microscopic in size)
a. Cooperia spp. and Strongyloides spp.
a. Bunostomum phlebotomum
3. Threadworms macroscopicc in size)
a. Capillaria bovis
4. Threadnecked worm
a. Nematodirus spathiger
a. Ascaris vitulorum
a. Monezia expansa and M. benedeni
F. Large Intestine
1. Nodular worm
a. Oesophagostomum radiatum
a. Trichuris discolor
3. Nine species of coccidia (Protozoan)
a. Eimeria zurnii
b. E. bovis
c. E. canadensis
d. E. ellipsoidalis
e. E. bukidnonensis
f. E. cylindrica
g. E. auburnensis
h. E. alabamensis
i. E. subspherica
G. Skin and Body Cavities
1. Filaria usually causing summer sores. May be seen in or
on any part of the body, however cattle navel region is
X. Life Cycles
A. All parasites of the Nematoda class are what is termed as direct
infectors. No intermediate host is required, with the exception
of filariae, which require an intermediate host such as biting
flies and mosquitoes.
1. Direct infectors depend on optimum moisture, temperature and
vegetative conditions to complete their life cycle. The eggs
are passed out of the host animal in the feces and hatch,
liberating a minute larva. This larva, after three molts, is
known as the infective stage, at which time it crawls upon
blades of grass and is eaten by the grazing animal. Upon
reaching the digestive tract the larva finds its suitable
location in the host and reaches sexual maturity, mates and
begins laying eggs.
2. Filariae depend upon mosquitoes or biting insects to complete
their life cycle. The female worms lay their larvae in the
host tissue. These larvae are picked up and circulated in the
blood stream and transferred to a new host by insect vectors.
The vector, feeding on the infected animal and taking. its
blood meal, sucks up the microscopic larvae, which further
develop in the insect and at a subsequent blood meal are re-
injected into another host animal.
B. All parasites belonging to the class Trematoda and class Cestoda
require an intermediate host.
1. Liver flukes, rumen flukes and others of the Trematoda class
require a fresh water snail to complete their life cycle. The
young flukes that hatch from the eggs burrow into the soft
tissue of snails, develop, and are liberated into water as
tadpole flukes. These young flukes swim around in water and
attach themselves to blades of grass and are subsequently eaten
by cattle. This stage in the life cycle is known as the in-
fective or encysted cercariae stage.
2. Tapeworms, of the class Cestoda, in cattle require as an inter-
mediate host a microscopic grass mite. The tapeworm segments
are passed in the fecal material to the ground. The grass
mites feeding in this material ingest the tapeworm eggs. These
eggs develop into the infective stage within the body of the
mites. The mites crawl on grass and are eaten with the
vegetation by animals normally grazing. Upon reaching the
digestive tract of the host, the infective stage of the tape-
worm is liberated and subsequently selects its normal location
in the small intestine, where it reaches sexual maturity and
begins its life cycle over again.
C. Phylum Protozoa, class Sporozoa, commonly known as coccidia, are
direct infectors. The animal becomes infected by eating food or
drinking water which has become contaminated with the coccidia
oocysts. Houseflies, birds, rats and man, etc. may serve as
mechanical means of transporting this infection.
XI. Damage done to the host.
A. In general parasites must live congenially with their host in
order to produce their kind; however, if by accident, over-
crowding, improper feeding, overgrazing or unsanitary farm
management practices the animals become excessively parasitized,
they succumb to the ravages of the parasites. The above state-
ment, however, is not true for the human tapeworm as man (the
host for the adult tapeworm) must eat the uncooked meat contain-
ing the infective cyst, which is found in beef muscle tissue.
B. Parasites, depending upon their location in the host and type of
food required for their existence, injure the animal by feeding
on blood, bacteria, tissue, bile, epithelium, lymph, or by
mechanical blocking of the essential physiological functions of
the respective organs or tissues of the body.
1. Internal parasite infection, whether it be in cattle or other
animals, cannot be seen in its protected home, wherever the
location in the body may be. They may be likened to a closed
book; you do not know of their presence or absence unless
accurate methods of diagnosis are utilized.
A. It is very difficult to describe the symptoms of parasite in-
fections in cattle. Furthermore, in heavily infected herds
there is usually a mixed infection of the various parasites.
Again, it is difficult to differentiate between the symptoms
of parasitism, malnutrition and mineral deficiency.
B. In general a parasitized animal is weak, emaciated, has a rough
hair coat and is anemic, as shown by paleness of the mucous
membranes of the eyes and mouth. Occasionally there is an edematous
swelling (bottle jaw) observed in liver fluke, hookworm and
stomach worm infection. It has been further observed that
these parasitized cattle may have a profuse diarrhea which
alternates with constipation. If hookworm infection is heavy
the fecal material will be black or blood tinged. In strongy-
loides infection there is a profuse, foul smelling diarrhea
intermixed with diphtheritic membranes. In lungworm infection
the symptoms are very pronounced in that the animals cough when
excited or driven. The mouth is held open, the tongue protrudes,
the head hangs low, and a creamy-like nasal discharge exudes
from the nostrils. The calf continually licks its nose, and in
later stages approaching death there is a definite abdominal
breathing and jugular pulse.
A. The most accurate method of determining parasitism is to sacrifice
the suspected animal either by slaughter or field autopsy. Open
each and every organ of the respiratory and digestive tract, making
careful inspection for the presence or absence of any parasites.
B. Whenever animals are slaughtered from your ranch it is advisable
to follow them to the packing house and to have the Veterinary
Inspector pay close attention to the organs to determine the
presence or absence of parasites. The inspectors and packers
are very cooperative and will gladly render a report on the para-
site findings in your animals.
C. To diagnose parasitism in the living animal, take directly from
the animal approximately 1/2 pint of fecal material and place in
a pint jar or similar waterproof, clean container, and leave in
the icebox overnight to chill. Hail this specimen to your local
veterinarian or to the Experiment Station for diagnosis and re-
commendations. Portions of these samples are examined micro-
scopically for the presence or absence of parasite eggs. Each
parasite egg has a distinct shape and color and can be readily
identified. In taking samples it is advisable not to pick
individual animals but to take a cross-section of your herd.
A negative specimen does not necessarily mean the animal is
free of parasites, but that the sample was free of parasitic
infection. It is advisable to make several periodic parasite
checks to determine the true picture in your herd. Observe
your animals closely for symptoms of parasitism.
A. Plant improved pastures, preferably of the taller growing grasses
such as pangola, torpedo, bahia, para, clover, etc. Low growing
vegetation such as carpet grass force animals to graze too close-
ly to the earth. Divide pastures into small acreage and rotate
cattle frequently, giving the grasses an opportunity to develop.
and in turn the cattle better grazing. Provide clean drinking
water from concrete or iron troughs, controlling the flow by
automatic floats. It is entirely impractical to rotate pastures
sufficiently long to eliminate parasites from cattle as it takes
from 10 to 12 months of nongrazing to eliminate parasites from
a given area. However, rotation of short duration is very
beneficial. Provide feeds such as hay and protein supplements
for the winter when the grasses are low. Keep before your
animals at all times a balanced mineral ration which is well-
protected from the weather. Avoid deep shade, low wet areas,
provide adequate drainage of muck pastures, and cap or other-
wise control artesian well flow. Do not allow standing water
in your pastures for a period of over 21 days, and if necessary,
drain with a V-type ditch.
A. Administer, either by bolus or drench, phenothiazine according to
the dose schedule which is found on the label of each and every
package. In general the dose of phenothiazine for cattle is
10 grams per 100 pounds live weight. Do not treat just visibly
sick animals, but treat all animals in that particular herd and
repeat treatment in 21 days. Furthermore, it is advisable to
continue this treatment in the fall and spring each year, especially
those animals under 18 months of age.
B. Administer hexachlorethane, as a drench, in doses of 10 grams per
100 pounds live weight, to all animals in herds where liver fluke
infection is found. Repeat in 21 days as the drug does not destroy
the immature flukes. Repeat periodically, as "A" above. In con-
junction with hexachlorethane treatment of cattle, drain your
pastures, control water, and treat all snail-infected areas with
copper sulfate to destroy the intermediate host snails.
XVI. There are a number of parasites of cattle which are not removed by
the two drugs mentioned above; however, the most pathogenic ones
are removed, allowing the animals to overcome the other infections.
Research is in progress to find drugs and methods to remove all
parasites from the animal without injury to the host. Parasites in
this group include lungworms, cooperia, hookworms, tapeworms, and