part of the abscess or cyst, then, with a syringe, wash out the sac with
carbolized water. If the abscess recurs, open it again, wash it out, and
inject tincture of iodin, or fill it with iodoform.
FUNGOID GROWTHS.
As a result of laceration or wound of any kind, fungous growths,
characterized by a raw, bleeding, granulating surface, with a tendency to
become pendulous, may develop on the ear.
_Treatment._--The whole tumor or diseased structure should be cut away, and
the wound treated daily with a dressing of carbolized cosmoline or
turpentine and sweet oil, 1 part of the former to 4 of the latter.
FOREIGN BODIES IN THE EAR.
Bugs have been known to gain entrance into the ears of animals. I once
removed an acorn from the ear of a cow that had been roaming in the woods;
also pieces of wood from a stanchion may be lodged accidentally in the ear.
_Symptoms._--There is usually a continuous uneasiness or frequent shaking
of the head, occasionally the manifestation of exceedingly great pain. The
animal may rub the head and ear against trees or other objects in an
endeavor to dislodge the offending body.
_Treatment._--A careful examination reveals the cause, which may be removed
with a pair of forceps or scraped out with a hairpin or piece of wire bent
at one end. If much inflammation exists, the ear may be swollen so that the
foreign substance is hidden from sight; then a probe may be inserted to
feel for the object, which, when found, should be removed, even if it
becomes necessary to split the ear at the base. Afterwards treat the ear
with frequent warm water fomentations and the injection of soapy water or
oil and water.
SCURFY EARS.
Cattle are subject to scurfy ears, which may be owing to a generally morbid
condition of the skin, or may be confined to the ears alone. The affected
animal shows an inclination to rub the ear; thick scales, which sometimes
have the appearance of hard, dry, horny scales, of scurf collect on it.
This condition is chiefly caused by a faulty secretion of the sebaceous
glands of the ear. Thoroughly clean the ear with a stiff brush, then anoint
it, so far as affected, with vaseline 4 parts to 1 part of white
precipitate ointment. If the scurfy ears are only a part of a general
scurfiness of the skin, the condition of the animal needs attention. (See
"Pityriasis," p. 329.)
FROSTBITE.
It is not uncommon among young cattle which are poorly nourished and
exposed outdoors to storms and extreme cold to suffer frostbite of the ear,
which may constitute actual freezing of the part.
_Symptoms._--Frostbite presents naturally every degree of severity from the
mere chilling of the tip of the ear to positive freezing and death of a
portion. In a day or two after the freezing has occurred the ear becomes
swollen and very painful; the dead part remains cold and begins to shrivel;
a line of separation then forms between the inflamed and the dead or dying
portion, and finally the piece destroyed drops off, leaving a raw healing
surface. When the ear is only slightly affected by the cold, an excoriation
or peeling off of superficial skin takes place, accompanied with some pain
and itching.
_Treatment._--A good liniment for frozen ears is a mixture of turpentine,
ammonia, and chloroform, of each 1 part, added to 6 parts of sweet oil. Rub
this on the ear several times a day. It will relieve pain and stimulate the
circulation, thus favoring a recovery of the injured structures.
LACERATIONS OF THE EAR.
Aggressive dogs are the most frequent cause of lacerated ear, generally
leaving a torn, ragged edge and bruised cartilage.
If the wound is extensive, a trimming of the ragged edges becomes
necessary; then the edges should be fastened together with silver wire,
catgut, or strong, thick, linen thread, taking a deep hold, and pine tar
applied.
DISEASE OF THE CARTILAGE AND NECROSIS.
Occasionally the cartilages of the ear become affected, usually the result
of a deep bruise; pus forms, burrows under the skin, and may find a
discharge from any part of the ear more or less distant from the seat of
the disease. When the cartilage has been extensively injured, pieces of it
may become dead (necrosed) and dissolve, to be carried away with the pus,
or it may lead to extensive sloughing and the formation of numerous running
sores. In the disease of the cartilage there is seldom much swelling or
great pain. The discharge is usually very offensive, and occasionally
streaked with blood. Whenever there is a long-continued, persistent
discharge from one or more openings in the ear, disease of the cartilage
may be suspected.
_Treatment._--The sinus formed by the passage of matter should be probed
and searched to the bottom for the presence of a foreign substance or the
evidence of decaying cartilage. When the probe touches necrosed cartilage
it will feel like a piece of dry leather or partially softened wood. A
counter opening must then be made at this place, and all diseased cartilage
cut away with the knife. The subsequent treatment consists in keeping the
artificial wound open for the discharge of pus, and the injection of
chlorid of zinc, 5 grains to the ounce of water, once or twice a day, until
the wound is healed.
ENCHONDROMA OF THE EAR.
This is an excessive growth of cartilage, found at the base of the ear in
the form of a hard, painless tumor, firmly attached to the movable ear. The
only recourse for its removal is the knife in the hands of one acquainted
with the anatomy of the part involved in the operation.
INFECTIOUS DISEASES OF CATTLE.
Revised by JOHN R. MOHLER, A. M., V. M. D.,
_Chief, Bureau of Animal Industry._
GENERAL INTRODUCTION.
The importance, to the farmer and stock raiser, of a general knowledge of
the nature of infectious diseases need not be insisted on, as it must be
evident to all who have charge of farm animals. The growing facilities for
intercourse between one section of a country and another, and between
different countries, cause a wide distribution of the infectious diseases
once restricted to a definite locality. Not only the animals themselves,
but the cars, vessels, or other conveyances in which they are carried may
become agents for the dissemination of disease. The growing tendency of
specialization in agriculture, which leads to the maintenance of large
herds of cattle, sheep, and hogs, makes infectious diseases more common and
more dangerous. Fresh animals are being continually introduced which may be
the carriers of disease from other herds, and when disease is once brought
into a large herd the losses become very high, because it is difficult, if
not impossible, to check it after it has once obtained a foothold.
These considerations make it plain that only by the most careful
supervision by intelligent men who understand the nature of infectious
diseases and their causes in a general way can these be kept away. We must
likewise consider how incomplete our knowledge concerning many diseases is,
and probably will be for some time to come. The suggestions and
recommendations offered by investigators, therefore, may not always be
correct, and may require frequent modification as our information grows
more comprehensive and exact.
An infectious disease may be defined as any malady caused by the
introduction, into the body, of minute organisms of a vegetable or animal
nature which have the power of indefinite multiplication and of setting
free certain peculiar poisons which are chiefly responsible for the morbid
changes.
This definition might include diseases caused by certain animal parasites,
such as trichinÊ, for example, which multiply in the digestive tract, but
whose progeny is limited to a single generation. By common consent the term
"infectious" is restricted to those diseases caused by the invasion and
multiplication of certain very minute unicellular organisms included under
the general classes of bacteria and protozoa. Nearly all the diseases of
cattle for which a definite cause has been traced are from bacteria. Among
these are tuberculosis, anthrax, blackleg, and tetanus (or lockjaw). Some
diseases, such as Texas fever and nagana, are traceable to protozoa, while
others, like actinomycosis and aspergillosis, are caused by fungi. Those
diseases of which the cause is unknown or imperfectly worked out are
pleuropneumonia, rinderpest, foot-and-mouth disease, rabies, cowpox,
malignant catarrh, and dysentery.
Bacteria may be defined as very minute, unicellular organisms of a
plantlike character. Their form is very simple, as may be seen from an
inspection of the various species depicted on Plate XXVIII. The description
of these figures will be found on page 360. The magnification there given
will furnish the reader some idea of their very minute size. They multiply
in two ways. The bacterium elongates and then divides in the middle to form
2 daughter cells. These go through the same process at once, and thus 4
cells are produced. The division of these leads to 8, the division of 8 to
16, and so on indefinitely. The rapidity with which this multiplication
takes place depends upon the nature of the bacterium. The bacillus of
tuberculosis multiplies very slowly, while that of anthrax does so with
great rapidity, provided both are in the most favorable condition. Another
mode of reproduction, limited to certain classes of bacteria, consists in
the formation of a spore within the body of the bacterium. Spore formation
usually takes place when the conditions pertaining to the growth of the
bacteria become unfavorable. The spores are much more resistant to
destructive agents than the bacteria which produced them. The anthrax spore
may live several years in a dried state, but the anthrax bacillus perishes
in a few days under like conditions. This matter will be referred to again
when we come to discuss the subject of disinfection.
Of the protozoa which cause disease very little is at present known. One
which produces Texas fever is pictured on Plate XLV, in figs. 4 and 5.
These parasites have a more complex life history than bacteria; and as they
can not be grown in artificial media, their thorough investigation is at
present hampered with great difficulties.
The differences in the symptoms and lesions of the various infectious
diseases are due to differences in the respective organisms causing them.
Similarly the great differences observed in the sources from which animals
become infected and the manner in which infection takes place are due to
differences in the life history of these minute organisms. Much discussion
has taken place of late years concerning the precise meaning of the words
"infection" and "contagion."
* * * * *
VARIOUS BACTERIA WHICH PRODUCE DISEASE IN CATTLE.
DESCRIPTION OF PLATE XXVIII.
The bacteria on this plate are partly from tissues, partly from cultures,
and stained artificially with aniline colors (fuchsin or methylene blue).
Figs 6 and 7 are copied from Fr‰nkel and Pfeiffer's atlas. All but fig. 7
are magnified 1,000 times; fig. 7, 500 times.
Fig. 1. Bacteria from pneumonia in cattle. These are also the cause of
hemorrhagic septicemia and are closely related to swine-plague bacteria.
These bacteria were drawn from a piece of spleen pulp (rabbit).
Fig. 2. Micrococci (streptococcus) which produce inflammation of the lining
membranes of the abdomen, thorax, heart, brain, and joints. Frequently
associated with the preceding bacteria in abscesses.
Fig. 3. Micrococci (staphylococcus) which produce inflammation and
suppuration; also pyemia.
Fig. 4. Bacilli of blackleg. The pale oval bodies as well as the light
spots in one end of the bacilli represent spores.
Fig. 5. Bacilli which produce tetanus or lockjaw. The light spot in the
enlarged end of each rod represents a spore.
Fig. 6. Bacilli of tuberculosis. Microscopic sections of a pearly nodule
from the lining membrane of the chest cavity. The bacilli are stained red
and appear as small straight rods within the cells of the nodule or
tubercle.
Fig. 7. Bacilli of anthrax. Bacilli from the spleen of a mouse inoculated
with a culture. The bacilli were obtained from the blood of a cow which
died of anthrax in Mississippi. The bacilli appear as rods stained blue.
The round bodies are blood corpuscles, also stained artificially.
[Illustration: PLATE XXVIII.
Haines del. ZEESE-WILKINSON CO., INC., N.Y.
VARIOUS BACTERIA WHICH PRODUCE DISEASE IN CATTLE.]
* * * * *
These words, however, are now wholly inadequate to express the complex
processes of infection, and it may be said that each species of bacterium
or protozoon has its own peculiar way of invading the animal body,
differing more or less from all the rest. There are, however, a few broad
distinctions which may be expressed with the help of these old terms.
Infection, as laid down above, refers at present in a comprehensive way to
all microorganisms capable of setting up disease in the body. Some
microorganisms are transmitted directly from one animal to another, and the
diseases produced may be called contagious. Among these are included
pleuropneumonia, rinderpest, foot-and-mouth disease, rabies, cowpox, and
tuberculosis. Again, certain organisms are perhaps never transmitted from
one animal to another, but may come from the soil. Among these are tetanus,
blackleg, anthrax to a large extent, and perhaps actinomycosis in part.
These diseases, according to some authorities, may be called miasmatic.
There is a third class of infectious diseases, the specific bacteria of
which are transmitted from one animal to another, as with the contagious
diseases, but the bacteria may, under certain favorable conditions, find
food enough in the soil and in the surroundings of animals to multiply to
some extent after they have left the sick animal and before they gain
entrance into a healthy one.
This general classification is subject to change if we take other
characteristics into consideration. Thus tuberculosis, because of its
insidious beginning and slow course, would not by many be considered
contagious in the sense that foot-and-mouth disease is; yet, in either
case, the bacillus must come from preexisting disease. The disease of
rabies, or hydrophobia, is not contagious in the sense that rinderpest is,
because the virus of rabies must be inoculated into a wound before it can
take effect; yet, in both cases, the virus passes without modification from
one animal to another, though in different ways.
Again, all the diseases under the second group, which seem to come from the
soil and from pastures, are in one sense contagious in that the virus may
be taken from a sick animal and inoculated directly, with positive results,
into a healthy animal. Other illustrations may be cited which show that
these old terms are not in themselves satisfactory. There are so many
conditions which enter into the process of infection that no single
classification will give a sufficiently correct or comprehensive idea of
it. These statements will be easily understood if the different infectious
diseases in the following pages are studied with reference to the way or
ways in which each disease may be contracted. Enough has been said,
therefore, to show that if we wish to make ourselves acquainted with the
dangers of any given disease, we must study it and not rely upon any single
work to tell the whole story.
Infectious diseases have, as a general rule, a period of incubation, which
comprises the time elapsing between the exposure to the infection and the
actual appearance of the disease. This period varies with the malady. The
most common symptom of this class of diseases is fever. The severity of the
fever is measured by the temperature of the animal; this is readily and
accurately ascertainable by the clinical thermometer. (See Pl. III, fig.
1.) The other symptoms are variable and depend upon the particular organ or
organs most implicated. Loss of appetite, cessation of rumination and milk
secretion, and general dullness are symptoms quite invariably present in
most infectious diseases.
During the course of infectious diseases secondary diseases or
complications may arise which are largely caused by bacteria other than
those producing the original malady. These complications are often so
severe as to become fatal. In general it may be stated that they are due to
filthy surroundings, and hence cleanliness may become an important aid to
recovery.
The treatment of infectious diseases is given under each malady so far as
this is allowable or advisable. These diseases are not, as a rule, amenable
to treatment. When the symptoms have once appeared the disease is liable to
run its course in spite of treatment, and if it is one from which animals
usually recover, all that can be done is to put them into the most
favorable surroundings. Many infectious diseases lead sooner or later to
death, treatment is useless so far as the sick are concerned, and it may be
worse than useless for those not yet infected. All animals suffering with
infectious diseases are more or less directly a menace to all others. They
represent for the time being manufactories of disease germs, and they are
giving them off more or less abundantly during the period of disease. They
may infect others directly or they may scatter the virus about, and the
surroundings may become a future source of infection for healthy animals.
This leads us to the subject of prevention as the most important of all
which claim our attention. In this place only a few general remarks will
suffice to bring the subject before the reader.
The most important thing is to keep disease away from a herd or farm. To do
this all sick or suspicious animals should be avoided. A grave form of
disease may be introduced by apparently mild or trivial cases brought in
from without. It is generally conceded that continual change and movement
of animals are the most potent means by which infectious diseases are
disseminated.
With some cattle diseases, such as anthrax, rinderpest, and
pleuropneumonia, preventive inoculation is resorted to in some countries.
This may be desirable when certain diseases have become established in any
locality so that eradication is impossible. It should not be practiced in
territories where a given disease may still be extirpated by ordinary
precautions. Preventive inoculation is applicable to only a few maladies,
and therefore its aid in the control of diseases is limited.
When an infectious disease has gained foothold in a herd the course to be
pursued will depend upon the nature of the malady. A good rule is to kill
diseased animals, especially when the disease is liable to run a chronic
course, as in tuberculosis. The next important step is to separate the well
from the sick by placing the former on fresh ground. This is rarely
possible; hence the destruction or removal of the sick, with thorough
disinfection of the infected locality, is the next thing to be done. As to
the disinfectants to be used, special directions are given under the
various diseases, to which the reader is referred. Here we will simply call
attention briefly to the general subject.
DISINFECTION AND DISINFECTANTS.
Disinfection consists in the use of certain substances which possess the
power to destroy bacteria or their spores, or both. Those which are
cheapest and most available for animal diseases are ordinary freshly slaked
lime or unslaked in powder, chlorid of lime, crude carbolic acid, corrosive
sublimate, formaldehyde gas, formalin, and compound cresol solution.
(1) Slaked lime is perhaps the most easily procured, but its disinfecting
power is limited. While it is capable of destroying all bacteria in their
vegetative state, it is unable to destroy such spores as those of anthrax
and blackleg. It is probable, however, that in incrusting spores it may
destroy their vitality sooner or later. It is regarded as safe practice to
use only spore-destroying substances for the virus of those diseases of
which we have no definite knowledge. Nevertheless, in the absence of other
disinfectants, lime is very useful. It may be employed as a whitewash on
wood and stone and sprinkled as a dilute wash or in powder over yards,
manure heaps, and over carcasses before they are buried, and over the
ground on which they have lain to prevent other animals from carrying the
infection away.
(2) Chlorid of lime is more efficient than simple slaked or unslaked lime,
as it destroys spores. It is the ordinary bleaching powder of commerce and
is quite unstable, hence old preparations, unless sealed, are of little
value. A 5 per cent solution is sufficiently strong for all spore-bearing
bacteria (3 ounces in 2 quarts of water). It may be efficiently applied to
the walls and floor of an infected stable by mixing with limewash in the
proportion of 6 ounces of the lime to each gallon of limewash. The ceilings
and those portions of the walls which can not be reached should be
disinfected by means of chlorin gas liberated from the chlorid of lime by
crude carbolic acid. This is accomplished by making a cone of 5 or 6 pounds
of chlorid of lime, in the top of which a deep crater is made for the
placement of from 1 to 2 pints of crude acid. The edge of the crater is
thereupon pushed into the fluid, when a lively reaction follows. The fumes
of chlorin are strongly irritating to the respiratory tract and therefore
all live stock should be removed before the work is started. Owing to the
heat generated, it is advisable to place the lime in an iron crucible and
to have nothing inflammable within a radius of 2 feet. The number and
location of these cones of chlorid of lime depend on the size and structure
of the building to be disinfected. As a rule, it may be stated that chlorin
gas liberated from the above-sized cone will be sufficient for disinfecting
5,200 cubic feet of air space.
(3) Crude carbolic acid. The ordinary purified carbolic acid is too
expensive to be used on a large scale, and the crude produce is a very good
substitute. This is made more powerful by mixing with it an equal volume
of commercial sulphuric acid. While the sulphuric acid is being added to
the crude carbolic acid much heat is evolved, and if the glass jar in which
the two are mixed is placed in cold water the resulting product is said to
have a higher disinfecting power. The mixture is added to water enough to
make a 5 per cent solution (about 7 ounces to 4 quarts of water). This is
strong enough for all purposes. It may be kept in wood or glass, but not
in metal, owing to the corroding action of the acid. It should be used
freely on woodwork and on infected floors, and a force pump of the kind
used by orchardists is very convenient as a means of applying the
disinfectant. If the solution is warm when applied, it will penetrate the
woodwork better than when cold, especially if the spraying is done during
cold weather. The addition of air-slaked lime in any quantity that will
dissolve in water to the above solution (say 1-1/2 pounds of lime to 7
ounces of crude carbolic acid to each gallon of water) is preferred by
many, as it makes any neglected places at once visible and leaves cleaner
and better air within the buildings. In most cases in which its
application becomes desirable--and this rule should apply to all
disinfections--the disinfected stables, stalls, etc., should remain vacant
as long as possible before cattle are again stabled therein.
(4) Mercuric chlorid, or corrosive sublimate, is a powerful disinfectant,
but it is likewise very poisonous; hence its uses are limited. Cattle are
especially susceptible to its action and caution must be used in its
application. A solution of one-tenth of 1 per cent is usually sufficient
(1 ounce to 8 gallons of water). It should not be placed in wooden pails,
which would form the tannate of mercury, a weak antiseptic; nor, owing to
its corrosive action, should expensive metal pails be used. Agate vessels
or tin pails are to be preferred. All solutions should be labeled "poison,"
and to avoid accidents none should be kept on hand.