losing condition despite the fact that its appetite is good and the food
nourishing. This is soon followed by a diarrhea which, while moderate at
first, soon becomes excessive and may be either irregular or persistent,
the feces being of the consistency of molasses and passed frequently. In
the meantime the hair becomes dry and harsh and the animal falls off
considerably in weight. The temperature, however, remains about normal. The
appetite does not seem to be greatly impaired until the last few weeks of
life, but nevertheless emaciation continues, the animal becomes more and
more anemic, great muscular weakness and exhaustion are manifested, and
death follows, apparently as the result of the persistent diarrhea and
great emaciation. The disease may continue for four or five weeks or may
last for a year, or even longer, before death intervenes.
_Lesions._--The lesions observed on post-mortem are remarkably slight and
are out of all proportion to the severity of the symptoms manifested. The
disease appears to start in the small intestines, especially in the lower
portion, where the lesions are usually the most marked, but it also
involves the large intestines, including the rectum. The mucous membrane
may alone be affected, although usually in the long-standing cases the
submucosa is also invaded and the entire intestinal wall is then much
thicker than normal and the tissue infiltrated with an inflammatory
exudate. The mucous membrane or inside lining membrane is markedly wrinkled
or corrugated, showing large, coarse folds with more or less reddening or
hemorrhagic patches or spots on the summits of the ridges, especially
noticeable in the large intestines. The mesenteric lymph glands are usually
somewhat enlarged and appear watery on section. The other organs do not
appear to be affected except from the anemia present in the later stages of
the disease.
_Differential diagnosis._--The principal disease with which bacterial
dysentery may be confused is tuberculosis, but the application of the
tuberculin test will readily diagnose the latter disease, while no reaction
will be noted in case the injected animal is suffering with the former
affection. The disease may also be mistaken for the parasitic affections
resulting from stomach worms (verminous gastritis) and intestinal
parasites, especially uncinariasis, but a microscopic examination of the
feces is necessary in order to establish definitely the diagnosis.
_Treatment._--As with all other forms of infectious disease, it is
advisable to separate immediately the diseased and suspected cattle from
the healthy animals. The feces passed by the former animals should be
placed on cultivated soil where healthy cattle will not be exposed to them,
as the bacilli producing the disease are readily found in such manure. The
stalls, stables, and barnyards should also be thoroughly disinfected, as
has been described under "Tuberculosis," in this chapter, special attention
being given to those places which have been soiled by feces. The
administration of medicines has thus far been quite unsatisfactory,
although treatment should be directed toward disinfecting the intestines
with intestinal antiseptics, such as tannopin in 1 dram doses twice daily,
and strengthening the animal by the use of stimulants such as strychnin in
half-grain doses given twice daily hypodermically. Salol, turpentine, or
subnitrate of bismuth in a starch or wheat-flour gruel may also give
temporary relief, but the diarrhea is likely to reappear and cause the
death of the animal. In all cases the feed must be carefully selected to
assure good quality, and should consist preferably of nutritious dry feed.
NAGANA.
Nagana, also called tsetse-fly disease, is an infectious fever occurring
chiefly in horses and cattle, characterized by alternating paroxysms and
intermissions and produced by a specific flagellate protozoan (_Trypanosoma
brucei_) in the blood. It is probably transmitted from animal to animal
solely by the bites of the tsetse fly. This insect is something like a
large house fly, and when it settles on a diseased animal, sucks the blood
and infects its proboscis, it is enabled on biting a second animal to
infect the latter by direct inoculation. This disease is found throughout a
large portion of central and southern Africa, along the low-lying and
swampy valleys. It has never occurred in the United States, nor is it known
to be present in the Philippines, but its relation to surra and the
possibility of its appearance in one of our island dependencies are the
reasons for including a few remarks at this time.
_Symptoms._--The chief symptoms in addition to the fever, which is usually
about 104∞ to 105∞ F., are the muscular wasting, progressive anemia, and
loss of power, together with the edema most marked about the head, legs,
abdomen, and genital organs. The urine is yellow and turbid, and
occasionally contains albumin and blood. There is paralysis of one or both
of the hind legs, difficult urination and defecation, labored breathing,
discharge from the eyes and nose, extreme thirst, and gradual extension of
paralysis to other parts of the body. The disease runs a chronic course,
lasting from three to six weeks in horses, and from one to six months in
cattle. Besides these animals, the mule, ass, buffalo, antelope, hyena,
camel, and dog contract the disease naturally, and sheep, goats, cats, and
small laboratory animals succumb to artificial inoculation.
_Lesions._--The spleen and lymphatic glands are enlarged. There are
sero-fibrinous exudates in the body cavities, the liver is enlarged and
engorged, heart flabby, and a catarrhal condition is present in the
respiratory passages. Pathological changes occur in the spinal cord. The
finding of the trypanosoma by microscopic examination of the blood will
be conclusive evidence for diagnosis.
_Treatment._--Treatment has not proved satisfactory. Quinin, arsenic,
methylene blue, and other drugs have been used, but without success.
Endeavors thus far made to produce immunity from this disease have likewise
been unavailing.
CATTLE FARCY.
This is a chronic disease of cattle occurring in France and the island of
Guadeloupe, West Indies. It is characterized by caseating nodular
swellings, first of the skin and afterwards of the superficial lymphatic
vessels and glands, finally proving fatal within a year by extension to the
viscera. The swellings rupture and discharge a purulent yellowish fluid,
which contains the causative organism. This affection, called farcin du
boeuf by the French, resembles cutaneous glanders or farcy of horses, but
is caused by an entirely different organism, the streptothrix of Nocard.
Moreover, cattle are immune from glanders, and for this reason the name,
unfortunately applied to this disease, should not lead to any confusion
with the cutaneous glanders or farcy of horses. Although the disease has
been described as occurring only in Guadeloupe and France, the possibility
of its occurrence in American possessions warrants its mention in this
chapter.
_Treatment._--Treatment consists in making incisions into the swellings and
syringing them out with 2 per cent compound cresol solution. The cavities
may then be packed with cotton, soaked in 5 per cent zinc-chlorid solution.
The swollen lymphatics may also be bathed or covered with cloths wrung out
in this solution.
OTHER INFECTIOUS DISEASES.
The following are also infectious diseases of cattle, a discussion of which
will be found in previous chapters:
Page.
Contagious abortion 167
White scour of calves 261
Infectious ophthalmia (pink eye) 345
FOOTNOTES:
[4] These membranes comprise the smooth, very delicate, glistening lining
of the large body cavities. In the thorax the serous membrane (pleura)
covers the ribs and diaphragm as well as the whole lung surface. In the
abdomen a similar membrane (peritoneum) lines the interior of the cavity
and covers the bowels, liver, spleen, etc.
[5] Hogs are subject to actinomycosis.
[6] The distribution of Government blackleg vaccine was discontinued July
1, 1922.
[7] Only a general outline of methods of eradication will be given here.
For detailed information, including directions for the construction of
dipping vats and for the preparation of dips, the reader is referred to
Farmers' Bulletin 1057, which may be obtained free upon application to the
Department of Agriculture, Washington, D. C.
[8] For fuller information see Farmers' Bulletin 1057, from which the
directions here given are mainly derived.
[9] The chemicals employed have no effect upon iron. They will, however,
actively corrode zinc, tin, or solder; hence a soldered pail must be
watched for leaks and is far inferior to a seamless pail, stamped from a
single sheet of iron. A tinned pail is preferred to a galvanized one, but a
plain iron seamless pail or an iron kettle should be obtained if possible.
[10] Best done by previously determining by measurement the depth of 5
gallons of water in the kettle. Set the kettle exactly level and mark the
depth on a stick held vertically on the center of the bottom.
ANIMAL PARASITES OF CATTLE.
By B. H. RANSOM, Ph. D.,
_Chief of Zoological Division, Bureau of Animal Industry._
The animal parasites of cattle comprise more than a hundred different
species, belonging to various groups of the animal kingdom. Fortunately not
all these parasites occur in this country--many are uncommon, and many are
comparatively harmless. Some forms, however, occur frequently, and some are
of distinct importance to the American stockman on account of the damage
for which they are responsible. It is these parasites particularly which
will be referred to in the present article, and although some forms are
discussed which are rare or apparently of little economic importance, most
of the minor and unusual parasites and species not found in this country
have been omitted from consideration.
FLIES.[11]
Of the various species of flies which infest cattle some are injurious on
account of the annoyance, pain, and loss of blood due to their bites, and
sometimes also on account of diseases or parasites which are thus
transmitted from the blood of diseased animals to that of healthy cattle,
while others, which in the winged adult state do not bite, are injurious
because they live parasitic on cattle during their larval stages.
_Remedies for flies._[12]--Most remedies used for protecting cattle from
the attacks of flies have to be applied frequently, and few, if any, will
keep flies away for more than a day or two following their application. The
numerous proprietary fly repellents to be found on the market are usually
more expensive, and often less efficacious than homemade mixtures.
At the Minnesota experiment station rancid lard 1 pound and kerosene
one-half pint, mixed thoroughly until a creamy mass forms, was found to
give excellent results as a fly repellent, lasting for two or three days,
when rubbed not too thickly with a cloth or with the bare hand over the
backs of cows. Mixtures of cottonseed oil and pine tar containing from 10
to 50 per cent of the latter substance were found by investigations in the
Bureau of Animal Industry to have a marked repellent action against flies
when applied lightly every day. A too free application of tar mixtures and
other preparations containing phenols is liable to cause poisoning; hence
care should be observed in this regard.
Jensen (1909) recommends the following formula, which is said to protect
cows for a week:
Common laundry soap 1 pound.
Water 4 gallons.
Crude petroleum 1 gallon.
Powdered naphthalin 4 ounces.
Cut the soap into thin shavings and dissolve in water by the aid of heat;
dissolve the naphthalin in the crude oil, mix the two solutions, put them
into an old dasher churn, and mix thoroughly for 15 minutes. The mixture
should be applied once or twice a week with a brush. It must be stirred
well before being used.
THE STABLE FLY (STOMOXYS CALCITRANS).[13]
This fly very closely resembles the house fly, but, unlike the latter, it
is a biting fly. It is common about stables and often enters dwellings,
especially in cloudy weather. According to NoÈ, it is the agent of
transmission of a parasitic roundworm of cattle
(_Setaria labiato-papillosa_, see p. 529). This fly has been shown capable
of transmitting anthrax from diseased to healthy animals, and under some
conditions it may transmit surra, a disease caused by a blood parasite
which affects horses, cattle, and other livestock.
The annoyance suffered by cattle and horses from stable flies is much
lessened if the stables are darkened.
The screening of doors and windows, however, is preferable, as ventilation
is not interfered with as it is in darkening stables. For milk cows
coverings made from burlap (double thickness), including trouserlike
coverings for the legs, may be used when the flies are very numerous and
troublesome. One of the fly repellents mentioned above may be applied to
cattle to protect them from stable flies. The Hodge flytrap fitted to the
windows of dairy barns is a useful means of destroying stable flies. The
United States Bureau of Entomology has found that a mixture of fish oil (1
gallon), oil of pine tar (2 ounces), oil of pennyroyal (2 ounces), and
kerosene (1/2 pint) is fairly effective for a short time when applied
lightly, but thoroughly, to the portions of animals not covered with
blankets. The risk of poisoning with tar mixtures as already mentioned
should be borne in mind in using this remedy. Care should be taken to apply
it lightly.
The stable fly breeds in moist accumulations of straw, chaff, cow or horse
manure, and various fermenting vegetable substances. The dÈbris collecting
in and under outdoor feed troughs, and the remains of straw stacks are
favorable breeding places for the stable fly. Under the most favorable
conditions about three weeks are required for development from the egg to
the adult stage.
The proper care of straw and the proper disposal of stable manure are very
necessary in the control of stable flies. Straw stacks should be carefully
built so as to shed rain, and loose straw or chaff should be scattered or
burned. Straw not required for winter feed should be promptly disposed of
by burning or scattering and plowing it under. Stable manure should be
hauled out and scattered at regular intervals, preferably every three days,
and the vicinity of stables should be kept free from accumulations of straw
and hay that may become wet and serve as breeding places for the stable
fly.
THE HORNFLY (LYPEROSIA IRRITANS).[14]
This fly, now found nearly everywhere in the United States, was introduced
into this country from Europe about the year 1885. Hornflies have the habit
of clustering about the base of the horn (fig. 2), whence the name by which
they are popularly known. They do not damage the horn, and congregate there
only to rest.
In view of the general practice of dehorning cattle, the name hornfly is
less distinctive than it once was. Moreover, hornflies rest on other parts
of the body as well as the horns.
When resting, their wings are held down close to the body (fig. 1); when
feeding, their wings are held out nearly at right angles, ready for flight.
They puncture the skin and suck blood, usually attacking the upper parts of
the body, particularly those which are out of reach of the animal's head or
tail. Unlike most flies, they remain on the animal more or less constantly,
day and night. Owing probably to the irritation and annoyance caused by
these flies, cattle often do not thrive as they should during seasons when
the flies are numerous. The hornfly has also been charged with transmitting
diseases, such as anthrax.
[Illustration: PLATE XLIV. NORMAL SPLEEN AND SPLEEN AFFECTED BY
TEXAS FEVER.
Fig. 1. SPLEEN OF AN ACUTE, FATAL CASE OF TEXAS FEVER.
Fig. 2. SPLEEN OF HEALTHY STEER.]
[Illustration: PLATE XLV. TEXAS FEVER.]
[Illustration: PLATE XLVI. THE CATTLE TICK (MARGAROPUS ANNULATUS),
THE CARRIER OF TEXAS FEVER.]
[Illustration: PLATE XLVII. THE CATTLE TICK (MARGAROPUS ANNULATUS).
Figs. 1 and 2 DORSAL AND VENTRAL VIEWS OF MALE.
Figs. 3 and 4 DORSAL AND VENTRAL VIEWS OF REPLETE FEMALE. (GREATLY
ENLARGED.)]
[Illustration: PLATE XLVIII.
PORTION OF A STEER'S HIDE, SHOWING THE TEXAS-FEVER TICK (MARGAROPUS
ANNULATUS) OF THE UNITED STATES. NATURAL SIZE. ORIGINAL.]
[Illustration: PLATE XLIX.
FIG. 1.--TICK-INFESTED STEER.]
FIG. 2.--DIPPING CATTLE TO KILL TICKS.]
[Illustration: PLATE L. FACSIMILE OF POSTER USED IN TICK ERADICATION
WORK.]
The fly lays its eggs in freshly dropped cow manure. They hatch in about 24
hours, and the larvÊ or maggots in four or five days develop to the pupal
stage, which lasts a week or 10 days. From the pupal stage the mature fly
emerges. The entire process of development from the deposition of the egg
to the appearance of the mature fly therefore may be completed in two
weeks, or even in a shorter time. To protect cattle from attacks of the
hornfly they may be treated with one of the remedies mentioned above (p.
502). Dipping cattle in a vat provided with splashboards set at the proper
angle destroys most of the hornflies present on the animals. Unless the
splashboards are used all but a few of the flies succeed in escaping as the
cattle plunge into the bath and later return to them. Scattering the
droppings of cattle with a shovel, or with brush dragged over pastures, in
order to insure the rapid drying of the manure and consequent destruction
of the larvÊ, is, when practicable, an efficient means of reducing the
number of these flies.
[Illustration: FIG. 1.--Hornfly (_Lyperosia irritans_) in resting
position. Enlarged. (From Bureau of Entomology.)]
[Illustration: FIG. 2.--Hornflies (_Lyperosia irritans_) on cow
horn. (From Bureau of Entomology.)]
BUFFALO GNATS.
These small flies, also known as black flies, are about one-eighth of an
inch long and have a characteristic "humped" back (fig. 3). They breed in
running water and appear in swarms during spring and summer, often in
enormous numbers, causing great annoyance to stock and human beings, on
account of their bites and their entrance into the eyes, nose, mouth, and
other openings of the body. Their bites appear to be poisonous, and in
seasons especially favorable to the gnats heavy losses of horses and cattle
often occur.
Buffalo gnats are more troublesome in bright, sunny weather than when it is
cloudy, and animals which have not shed their winter coats suffer more from
their attacks than those with smooth coats. Cattle kept in darkened stables
are not molested. The application of one of the fly repellents already
mentioned (p. 502) may help to protect animals from buffalo gnats. The
burning of smudges is also a useful means of protecting stock from the
attacks of these flies.
[Illustration: FIG. 3.--Buffalo gnat. Enlarged. (From Bureau of
Entomology.)]
SCREW WORMS.[15]
Screw worms (fig. 4) are the maggots of a fly (_Chrysomyia macellaria_), so
called from their fancied resemblance to a screw. The adult fly (fig. 5) is
about one-third of an inch long, with a bluish-green body, red eyes, and
with three dark longitudinal stripes on the back (thorax). Attracted by
odors of decay, it deposits its eggs, 300 to 400 at a time, in cuts, sores,
castration wounds, etc. The crushing of a tick on the skin commonly results
in screw-worm infection at that point. The eggs hatch in a few hours and
the larvÊ or maggots, or so-called screw worms, begin to burrow into the
flesh and continue burrowing and feeding from three to six days, after
which they leave the wound and crawl into the earth, there transforming
into the quiescent pupal stage. This stage is completed in three to
fourteen days. The mature flies then emerge from the pupal envelope and are
soon ready for egg laying. From two to three weeks are therefore required
for the entire life cycle, although under certain conditions it is possible
for the fly to undergo its full development in as short a time as seven
days, and on the other hand as long as a month is often required.
Besides cattle, the screw-worm fly attacks sheep, horses, dogs, and man. In
the case of hogs it is generally the ears which are affected. The fly also
breeds in dead animals, and all carcasses should therefore be buried deeply
or burned. The complete destruction of all dead animals by burning has been
found by the Bureau of Entomology to be by far the best method of
controlling screw worms.
_Treatment for screw worms._--For proper treatment an animal suffering from
screw worms should be caught and thrown. Chloroform is then poured into the
wound, taking care that it penetrates thoroughly into all the burrows of
the screw worm, if necessary using a slender stick or a small bunch of
twisted hay as a probe. The animal should be held for several minutes in
order to insure the continued action of chloroform. Instead of chloroform,
gasoline may be used, and carbon tetrachlorid is said by some authorities
to give good results. Finally, the dead or dying maggots may be removed
with forceps, the wound washed with a weak carbolic or cresylic acid
solution, and painted with pine tar to reduce the chances of further attack
by flies. Finally the wound should be dressed with a carbolic or cresylic
ointment to promote healing and thus prevent further infection, or the
wound may be painted with pine tar. Dipping in the arsenical dips used for
destroying cattle ticks is a convenient method of treatment if many animals
are involved.
[Illustration: FIG. 4.--Screw worm (larva of _Chrysomyia
macellaria_). Enlarged. (From Bureau of Entomology.)]
[Illustration: FIG. 5.--Screw-worm fly (_Chrysomyia macellaria_).
Enlarged. (From Bureau of Entomology.)]
GRUBS, WARBLES, BOTS.
Ox warbles are whitish or, when full grown, dark-colored grubs or maggots
that develop from the eggs deposited on the hairs of cattle by certain
flies known as warble flies. In the United States there are two species of
ox-warble flies, technically known as _Hypoderma lineatum_ and _Hypoderma
bovis._ These flies somewhat resemble bees in their general appearance, but
like all flies have only two wings.
The first named, _H. lineatum_, is commonly called the heel fly and is more
generally distributed over the United States than the other species. The
tail has a distinctive reddish-orange color and the legs are rough and
hairy. This fly commonly deposits its eggs about the coronet, whence the
name of heel fly, and on the fetlocks, knees, and hocks. When cattle are
resting, eggs are deposited along the line of contact of the body with the
soil. Cattle are frequently indifferent to the activity of this fly in
depositing its eggs. Commonly 8 to 10 eggs, sometimes as many as 14, are
attached to a single hair.
In the United States the other warble fly, _H. bovis_, has been found only
in the North (New England, New York, Pennsylvania, Maryland, Michigan,
Iowa, Missouri, and Washington) and has not yet been found in the Southern
States. The tail is orange-yellow, lighter in color than that of the other
species, and the legs have but few hairs. This fly commonly deposits its
eggs on the outside of the hind quarters and above the fetlocks when the
animals are moving, or lower down if they are quiet. Cattle are usually
much disturbed by the activity of this fly and not infrequently appear
terror stricken. The eggs are attached singly, one egg to a hair near its
base.
The eggs of the warble flies hatch as a rule in about a week, the time
varying with local conditions. The young warble is about 1 mm. (1/25 inch)
long. It crawls to the base of the hair and burrows into the hair follicle.
The entrance of the larvÊ frequently causes sudden appearance of swellings.
The larvÊ of _H. bovis_ in entering the skin rarely cause a flow of serum
or pus formation, but those of _H. lineatum_ commonly cause a considerable
flow of serum with pus formation resulting in a matting of the hair on
affected areas of the skin. The warbles after penetrating the skin migrate
through the body and ultimately reach the backs of the cattle, _H.
lineatum_ usually appearing there in northern latitudes about the middle of
December and _H. bovis_ about a month later. During their migrations,
before they reach the back, the young warbles spend a considerable period
in the walls of the esophagus, or gullet, and may be found in this location
as early as August 15. During the fall and winter a large proportion of the
gullets of cattle that are slaughtered are found to be infested with
warbles, and are known as grubby gullets or weasands in the packing houses.