United States. Bureau of Animal Industry.

Special report on diseases of cattle and on cattle feeding online

. (page 9 of 56)
Online LibraryUnited States. Bureau of Animal IndustrySpecial report on diseases of cattle and on cattle feeding → online text (page 9 of 56)
Font size
QR-code for this ebook

ticable and a ligature can be applied as in the case of a bite to one of
the limbs, no time should be lost in applying it above the injury. It
should be made sufficiently tight to as far as possible arrest circulation"
in the bitten part. The poison should be extracted by cupping. If
tliis is not practicable, or when it has been performed, the wound
should be seared with a red-hot iron to destroy as far as possible any
of the poison that may remain unabsorbed. The depressing effect of
the poison on the general system should be counteracted by liberal
drenching with stimulants, wine, brandy, whisky, etc. In the human
being preparations of arsenic, bromine, bichloride of mercury, and
iodido of potassium in frequently-repeated doses are indicated. In
animal practice the alcoholic stimulants and local treatment above
described arc likely to meet with best success. In the emergency which
arises when such an accident occurs the means at hand must be used to
the best advantage. First the application of a tight ligature can nearly
always be made; then opening the wound up to its bottom with a pen-
knife and encouraging free flow of blood will be likely to wash out at
least part of the poison, if done promptly. Capping can not be practiced
among cattle with the same facility as it can in the human being, owing
to the covering of hair. This obstacle may be overcome by smearing
the hair full of tar or balsam on the surface to which the cupping glass
is to be applied. The operation may be easily performed, using a jar or
bottle with a good-sixed neck, but not so large as to prevent its having a
firm seat on the skin around the wound. A piece of cloth dipped in oil
ami lighted is dropped into the bottle, the neck of which is quickly
applied t< the wound. The llame of the liurning cloth consumes the


oxygeii of the air and creates a partial vacuum into which the blood
from the wound should flow freely. The injection hypodermically of a
20 per cent solution of permanganate of potash directly into the wounded
tissues aids in neutralizing the effect of the concentrated poison in the
immediate vicinity.


By W. H. HARBAUGH, V. S., Richmond, Va.

Iii order to comprehend what is meant by disease, it is essential that
one should understand the structure and arrangement of the organs
subject to disease, as well as know something of the phenomena or
functions of the organs in a state of health, because it must be remem-
bered that disease is but a perversion of health. The blood and circu-
latory apparatus are not only of the greatest importance in the diseases
under this particular head, but they are more or less concerned whenever
disease exists. To convey an idea of their importance it may be stated
that all vitality and all nutrition depend on the blood. In view of
these facts it must be admitted that nothing less than a liberal descrip-
tion of these organs and their functions will suffice in a work of this
kind (the principal object of which is instruction), and therefore we
will at once proceed to an anatomical and physiological consideration
of them.

The heart, blood-vessels, and lymphatics are usually described as
the circulatory apparatus.

The heart is located in the thoracic cavity (chest). It is conical in
form, with the base or large part uppermost, while the apex or point
rests just above the sternum (breastbone). It is suspended from the
vertebral column (backbone) by the large blood-vessels which enter
and leave the heart. It is situated between the right and left lung,
the apex inclining to the left, and owing to this circumstance the
heartbeats are best felt on the left side of the chest behind the elbow.
The heart is composed principally of muscular tissue. It may be con-
sidered as a hollow muscle, containing four compartments, two on each
side. The compartments of each side are placed one above the other.
For convenience, the compartments are called" right and left, but in
reality those called right arc almost in front of those called the lot'T.
The upper compartments are called auricles and the lower ones are ealled
ventricles. The right auricle and ventricle are completely separated
from the left auricle and ventricle by a thiek septum or wall, so that
there is no communication between the right and left sides of the heart.
Externally the heart appears to be single, but it is really a double organ.



The communication between the auricle and ventricle of either side is
called the auriculo-ventricular opening, and both orifices are regulated
by valves. The compartments of the heart are manifest on its outer
surface by grooves or furrows. There is a transverse groove which
marks the division between the auricular and ventricular parts. This
groove also marks the location of the auriculo-ventricular openings on
the inside. The upper portion of the heart is constricted in the middle
of its superior face; the section on either side of the constriction repre-
sents one of the auricles. Into the right section are inserted the pos-
terior vena cava, the anterior vena cava, the vena azygos, and coronary
vein. Into the left section are inserted the pulmonary veins, usually
four in number. The ventricular portion includes all that is below the
transverse groove; it is much the greater portion of the organ and gives
to it the shape of a cone or pyramid. On either face is seen a groove
which marks the division between the right and left ventricle. In
cattle an accessory groove runs down behind the left ventricle. All
the grooves are occupied by blood-vessels and fatty tissue. The com-
mon aorta and the pulmonary artery leave the upper portion of the
ventricular mass on the left of the anterior part.

The cavities of the heart are designated as the right and left, and
there is no communication between the right and left cavities after the
birth of the young animal. During the life of the fetus in the womb
there is an opening in the wall between the right and left auricles
called the foramen ovale, but at birth this is closed, and there remains
only a depression in the wall to mark the place where it existed. It
occasionally happens that the foramen ovale remains open after birth,
and this exception will be referred to hereafter under the head of
Cyanosis. In the cavities are to be seen the orifices of the vessels
(through which the blood enters and leaves the heart), the names of
which have been given.

At the bottom of each auricle is the auriculo-ventricular opening;
each opening is provided with a valve to close it when the heart con-
tracts to force the blood into the arteries. In the interval between the
contractions these valves hang down into the ventricles. Little ten-
dinous cords stretching from the free edges of the valves to the walls
of the ventricles prevent the blood from forcing the valves too far up
into the auricles during contraction of the heart, which prevents the
return of blood into the auricles.

The opening of the common aorta and pulmonary artery and the
ivuriculo- ventricular openings are surrounded bj' rings of fibrous tissue
which form the frame on which the muscular tissue of the heart rests.
In cattle there are found two small bones in the fibrous tissue of the
ring of the common aorta. The fibrous tissue completely surrounds
the openings of the aorta and pulmonary artery, but the rings around
the auriculo- ventricular openings are incomplete.

The muscular tissue of the heart belongs to that class known as in-


voluntary, because its action contraction is not controlled by the
will; but it is well to remark that it is a variety of striated or striped
muscle, and striped muscle, with but few exceptions, of which this is
one, belongs to the class known as voluntary muscle.

The nutrition of the heart is derived from the blood distributed to its
muscular tissue by the coronary arteries (and their branches), which
arc the only vessels given off by the common aorta before it divides
into the posterior and anterior aortas. The branches of the coronary
arteries are the vessels which occupy the furrows on the external sur-
face of the heart. The venous blood from the structure of the heart is
emptied into the right auricle by the coronary vein. The lymphatics
of the heart accompany the course of the coronary arteries and empty
into the lymphatic glands near the base of the heart. The nervous
supply of the heart is from the cardiac plexus, which is derived from
the pneumogastric and sympathetic nerves.

The cavities of the heart are lined by a kind of serous membrane
called the endocardium. It is very thin and closely adherent and forms
the internal surface. The endocardium may be considered as continued
into the veins and the arteries, forming their internal lining. In the
cavities of the right side the endocardium has a reddish tint, which is
deeper in the ventricle; in the cavities of the left side the tint is yel-
lowish. The walls of the ventricles are thicker than those of the auri-
cles, and the walls of the left ventricle are much thicker than those of
the right.

The heart is enveloped by a fibrous sac (or bag) called the pericar-
dium, wliich assumes much of the general shape of the outer surface of
the heart. The internal surface of the pericardium is smooth and
glistening like the external surface of the heart itself. These smooth
surfaces are opposed one to the other, and are in fact the serous mem-
brane of the pericardium; they are kept moist by the serum which
exudes from their surface to prevent the serious consequence of friction
to the surface of the heart. In health no appreciable quantity of fluid
collects in the sac, but in some cases of disease, and in instances of old
ft, serum accumulates within the pericardium to a greater or !:-;>

The heart is the principal organ of the circulatory apparatus, and its
function is to assure the movement of the blood by the regular contrac-
tion of its walls which force the blood into the vessels called arteries.
The auricles may IMJ considered as the reservoirs or receivers of the
blood, and the v.-nn !<!.> as the puuips, therefore the function of the
heart, resembles the action of a force pump. During the interval be-
tween contractions, the heart being in momentary repose, the blood
pours into the auricles from the veins; the auriculo- ventricular orifices
being widely open, the ventricles also receive blood; the aurirles con-
tract and the ventricles are filled; contraction of the ventricles follows;
the auriculo- vi'iitr.'cular valves arc forced up by the pressure of the


blood and close the uuriculo-ventricular openings, and prevent the re-
turn of blood into the auricles; the contraction of the ventricles forces
the blood from the right ventricle into the lungs through the pulmonary
artery and its branches, and from the left ventricle into the aorta and
all parts of the body through the arteries. After the contraction of the
ventricles the heart is again in momentary repose and being filled with
blood, while the valves in the aorta and pulmonary artery close to pre-
vent the return of blood into the ventricles. (See Plate vu.)

The heart is the most irritable muscle in the body; it has no rest
from the time the first few cells are formed that go to make up the
organ until its action is stopped by death, except during the repose or
momentary pause between the beats.

The average weight of the heart of an ox is said to be from 3 to 4
pounds, but, of course, the weight must be very variable in different
animals owing to the many breeds and sizes of cattle.

The vessels that convey the blood from the heart to all parts of the
body are called arteries; the vessels which return the blood to the
heart are called veins. Between the ultimate ramifications of the ar-
teries and the beginning of the veins there is an intermediate system
of very minute vessels called capillaries, which connect the arterial
with the venous system of the circulation.


The walls of the arteries are possessed of a certain amount of rigid-
ity sufficient to keep the tubes open when they are empty; this fact
led the ancients to believe that they contained air and hence their
name arteries. The walls of the arteries are composed of three coats
or tunics. The internal coat may be considered a prolongation of the
endocardium from the left ventricle. The middle coat is composed of
yellow elastic tissue and muscular tissue; the amount of each tissue
varies according to the size of the vessel. The muscular tissue being
contractile is required in some parts more than in others. In the aorta
and large arteries near the heart the elastic tissue predominates; in the
vessels of intermediate size the elastic and muscular tissues average
about equal proportions, while in the smallest arteries the muscular
tissue predominates and even comprises the entire middle coat. The
external coat is composed of a layer of thin but remarkably strong
fibrous tissue and a small proportion of elastic tissue.

A ligature may be tied sufficiently tight around an artery to com-
pletely rupture the middle and internal coats without severing the ex-
ternal coat; and owing to the fact that the union is not complete between
the middle and external coats, the ruptured coats retract within the
external one, assisting to a great extent in surgery. The blood leaves
the left ventricle through a single vessel, the common aorta, which
divides into the anterior and posterior aortas, which in turn give ofl'
the large arteries.


The arteries divide and subdivide (like the branches of a tree) be-
come smaller and smaller, and ultimately ramify into every part of the
body, terminating in a network of very small tubes called capillaries,
which can only be recognized by the aid of a microscope. The walls
of the capillaries differ considerably from the walls of the arteries and
veins, and they also vary according to the size of the capillary tubes;
they are so thin and peculiar that white corpuscles and the fluid part
of the blood readily pass through them into adjacent tissue. The capil-
laries terminate in veins.

The veins take the blood from the capillaries in all parts of the body.
They begin in very small tubes which unite to become larger in size
and less in number as they approach the heart. The veins, like the
arteries, have three coats, but are' thinner, less muscular, and less
elastic than the arteries, and collapse when empty.

In its course an artery is iisually accompanied by a vein, and in many
in stances by two veins; in the latter case it is placed between them,
and if but one vein accompanies it, the artery is always the deeper and
least exposed of the two vessels. Nerves also generally accompany
the arteries. Muscles in many locations serve to point out the situation
of arteries, as they often are in contact with them in their course; cer-
tain arteries are in contact witli bones; and in certain situations they
lie in the connective tissue between the skin and bone, which is the
case with some of these vessels about the head and legs ; such arteries
are best for ascertaining the state of the pulse. Arteries deeply seated
in certain places are in contact with bones, and the knowledge of their
location enables the surgeon to compress them against the bone for the
purpose of arresting the flow of blood in a particular vessel in case of
hemorrhage or during operations. The more important arteries are
placed deep within the body; but in those cases where they are super-
i;ci;il, tlu-y are generally found where least exposed to injury, as for
example, on the inner side of the legs. Arteries are less numerous
than veins, and the total capacity of the arteries is much less than that
iie veins. A great number of veins are in the tissue immediately
beneath the skin, and these are not generally accompanied by arteries.
All the superficial veins, and many of the others, have valves within
t hem to prevent the reflux of blood; the faces of the valves are towards
the heart, and when anything interferes to retard the flow of blood to
tin- heart, the valves are closed by the backing of the blood, and effect-
ually prevent its return. By the same means these valves favor the
llo\\- of blood to the heart, because of the pressure assured by the con-
lion of muscles adjacent to the veins. There are no valves in th;
vein*, of the lungH.

The. blood throughout its course, in the heart, arteries, capillaries, and
veins, is inclosed within these vessels. There is no opening into the
course of the blood, except where the large- lymphatics empty into the
v< nous blood.


The circulation is. considered as two systems: The pulmonary, the
lesser, is that from the right heart to the lungs, and back to the left
In-art. The systemic, or greater, is from the left heart to all parts of
the body, and back to the right heart. To simplify the subject it niay
be fiaid at once that the blood of the body is of two colors
bright red, or pure blood, and dark red, or impure blood. All the;
arteries, except the pulmonary artery and its branches, carry bright
red ; and all the veins, except the pulmonary veins, carry dark-red blood.
The impure dark-red blood is collected from the capillary vessels and
carried to the right auricle by the veins 5 it pusses through the auriculo-
ventricular openings into the right ventricle and thence into the pul-
monary artery, and through its branches to the capillaries of the lungs,
where the carbonic acid gas and other impurities are given up to the
air in the air-cells of the luogs (through the thin walls between the
capillaries and air-cells), and where it also absorbs from the air the
oxygen gas necessary to sustain life, which changes it to the bright red,
pure blood. It passes from the capillaries to the branches of the pul-
monary veins, which convey it to the left auricle of the heart; it then
passes through the auriculo- ventricular opening into the left ventricle,
the contraction of which forces it through the common aorta into the
posteiior and anterior aortas, and through all the arteries of the body
into the capillaries, where it parts with its oxygen and nutritive ele-
ments, and where it absorbs carbonic acid gas and certain other impuri-
ties and becomes dark colored. (See theoretical diagram of the circu-
lation, Plate vn.)

The muscular tissue in the walls of the arteries, under the stimulus
of the vaso-niotor nerves, regulates the caliber of the vessels and the
amount of blood supplied to the different parts, and, on account of its
contractibiUty, it assists in controlling a hemorrhage when an artery is
cut completely across, by causing the retraction of the severed ends of
the vessel.

The flow of blood through the capillaries is very slow, not much more
than an inch a minute. The power which forces it through them is the
heart; and many physiologists maintain that the changes in the blood
which take place in the capillaries favor and compel the blood to flow
through them, and as a proof they refer to the fact that arteries are
found empty after death, because the capillaries have sent the blood
into the veins. On this theory, capillary circulation may be compared
to oil rising in the wick of a lamp to burn as the demand requires.

The blood is caused to flow through the veins to the heart by several
different forces. The contraction of muscles in proximity to veins
causes a pressure on them which assures -an onward movement to the
heart, since the valves in the veins prevent its backward movement.
At each inspiration (or taking in a breath, there is a suction-like action
of the chest, which induces the flow to the right auricle. The heart
probably exerts P, force from behind which assists the flow in the veins.



The branches of certain arteries in different parts unite again after
subdividing. This reuniting is called anastomosing, and assures a
quota of blood to the part if one of the anastomosing arteries should be
tied in case of hemorrhage, or should be destroyed by accident or oper-
ation. In such cases the blood is supplied by the collateral vessels of
the anastomoses, which gradually enlarge, because the increased quan-
tity of blood they are forced to carry distends their walls, and even-
tually the part receives all the blood it requires. Were it not for these
anastomoses, certain parts would be deprived of blood in certain cases
of accident and disease, and mortification would ensue.

Anastomoses are effected when two branches, after traversing a cer-
tain length, reunite to form a vessel larger than either of the branches;
others are formed by transverse communications through smaller arter-
ies between two larger ones running in the same direction; and they
may be formed by a combination of both the foregoing methods. Veins
also form anastomoses, and they are even more numerous than those

of the arteries.


The various kinds of food, after being digested in the alimentary
ranal, arc absorbed and carried into the blood by the lymphatics, and
by tin 1 blood to the places where nutrition is required. The blood
takes fnm all parts of the body all that is useless and no longer
required, ami carries it to the different organs where it is eliminated
from the body. It contains within itself all the elements which nour-
ish the body.

The blood may be considered a fluid holding in solution certain inor-
ganic elements and having certain bodies suspended in it. Authorities
differ as to the exact amount of each constituent of the blood, but the
following is a fair estimate: In 1,000 parts there are: water, 790 parts;
corpuscles, 120 parts; albumen, GO parts; salts and extractive matters,
iiii hiding the elements of fibrin, 30 parts. To facilitate description,
the bl<xxl may be considered as being made up of the corpuscles and
tho liquor sanguinis. The corpuscles are of two kinds, the red and the
white, the red being the most numerous. The color of the blood is duo
to the coloring matter in the red corpuscles. The red corpuscles are
the oxygen carriers. Roth kinds are very minute bodies, which re-
quire the aid of the microscope to recognize them. The liquor san
guinis is composed principally of water, salts, albumen, and the
elements of fibrin. The most abundant salts are the chloride and the
carbonate of soda, with a less quantity of the phosphate and sulphate
of potassium and lime. The albumen very much resembles the white
of an egg in its composition. Fatty matters exist in the liquor san-
guiuis iu extremely small particles, and also in combination with soda.


The extractives are different elements in such small proportions as to
require special means to extract them. Fibrin does not exist in the
living blood as fibrin, but the elements are there, ready to form fibrin
under certain circumstances. The internal lining of the blood-vessels
appears to prevent the formation of fibrin, but when the blood conies
in contact with anything foreign to it, fibrin is quickly formed, and
coagulation (or the clot of blood) is the result, unless certain means
are used to prevent it. Fibrin is a very important factor in surgery.
When a wound is made and blood escapes, fibrin is formed, which
'auses the blood to coagulate or clot, and which materially assists in
arresting hemorrhages. Carbonic acid gas is carried by the liquor san-
guinis, both in solution and combined with the soda.

The blood is alkaline, due to the salts it contains. Its specific gravity
varies from 1.050 to 1.057. The weight of blood in cattle is estimated
by a good authority to be 1 pound to every 23 pounds of the weight
of the body.

The lymphatics, or absorbents, are the vessels which carry the lymph
and chyle into the blood. Like the veins, they have three coats or
tunics, but much thinner. They begin as capillaries in all parts of the
body, and they have valves. Placed along the course of the lymphatic
vessels are glands, and in some situations these glands are collected
into groups; for example, in the groin, etc. These glands are often
involved in inflammation arising from the absorption of deleterious
matter. For instance, a sore may be on a finger, and the lymphatic
capillaries there may absorb a poisonous or irritable matter, which is
carried by the lymphatic vessels to the collection of lymphatic glands

Online LibraryUnited States. Bureau of Animal IndustrySpecial report on diseases of cattle and on cattle feeding → online text (page 9 of 56)