certain bubbling sounds may be heard that are known as peristaltic
sounds, because they are produced by peristalsis, or wormlike
contraction of the intestines. These sounds are a little louder on the
right side than on the left on account of the fact that the large
intestines lie in the right flank. Absence of peristaltic sounds is
always an indication of disease, and suggests exhaustion or paralysis of
the intestines. This may occur in certain kinds of colic and is an
unfavorable symptom. Increased sounds are heard where the intestines are
contracted more violently than in health, as in spasmodic colic, and
also where there is an excess of fluid or gas in the intestinal canal.
The feces show, to a certain extent, the thoroughness of digestion. They
should show that the feed has been well ground, and should, in the
horse, be free from offensive odor or coatings of mucus. A coating of
mucus shows intestinal catarrh. Blood on the feces indicates severe
inflammation. Very light color and bad odor may come from inactive
liver. Parasites are sometimes in the dung.
Rectal examination consists in examination of the organs of the pelvic
cavity and posterior portion of the abdominal cavity by the hand
inserted into the rectum. This examination should be attempted by a
veterinarian only, and is useless except to one who has a good knowledge
of the anatomy of the parts concerned.
THE EXAMINATION OF THE NERVOUS SYSTEM.
The great brain, or cerebrum, is the seat of intelligence, and it
contains the centers that control motion in many parts of the body. The
front portion of the brain is believed to be the region that is most
important in governing the intelligence. The central and posterior
portions of the cerebrum contain the centers for the voluntary motions
of the face and of the front and hind legs. The growth of a tumor or an
inflammatory change in the region of a center governing the motion of a
certain part of the body has the effect of disturbing motion in that
part by causing excessive contraction known as cramps, or inability of
the muscles to contract, constituting the condition known as paralysis.
The nerve paths from the cerebrum, and hence from these centers to the
spinal cord and thence to the muscles, pass beneath the small brain, or
the cerebellum, and through the medulla oblongata to the spinal cord.
Interference with these paths has the effect of disturbing motion of the
parts reached by them. If all of the paths on one side are interfered
with, the result is paralysis of one side of the body.
The small brain, or cerebellum, governs the regularity, or coordination,
of movements. Disturbances of the cerebellum cause a tottering,
uncertain gait. In the medulla oblongata, which lies between the spinal
cord and the cerebellum, are the centers governing the circulation and
breathing.
The spinal cord carries sensory messages to the brain and motor
impressions from the brain. The anterior portions of the cord contain
the motor paths, and the posterior portions of the cord contain the
sensory paths.
Paralysis of a single member or a single group of muscles is known as
monoplegia and results from injury to the motor center or to a nerve
trunk leading to the part that is involved. Paralysis of one-half of the
body is known as hemiplegia and results from destruction or severe
disturbances of the cerebral hemisphere of the opposite side of the body
or from interference with nerve paths between the cerebellum, or small
brain, and the spinal cord. Paralysis of the posterior half of the body
is known as paraplegia and results from derangement of the spinal cord.
If the cord is pressed upon, cut, or injured, messages can not be
transmitted beyond that point, and so the posterior part becomes
paralyzed. This is seen when the back is fractured.
Abnormal mental excitement may be due to congestion of the brain or to
inflammation. The animal so afflicted becomes vicious, pays no attention
to commands, cries, runs about in a circle, stamps with the feet,
strikes, kicks, etc. This condition is usually followed by a dull,
stupid state, in which the animal stands with his head down, dull and
irresponsive to external stimuli. Cerebral depression also occurs in the
severe febrile infectious diseases, in chronic hydrocephalus, in chronic
diseases of the liver, in poisoning with a narcotic substance, and with
chronic catarrh of the stomach and intestines.
Fainting is a symptom that is not often seen in horses. When it occurs
it is shown by unsteadiness of gait, tottering, and, finally, inability
to stand. The cause usually lies in a defect of the small brain, or
cerebellum. This defect may be merely in respect of the blood supply, to
congestion, or to anemia, and in this case it is likely to pass away and
may never return, or it may be due to some permanent cause, as a tumor
or an abscess, or it may result from a hemorrhage, from a defect of the
valves of the heart, or from poisoning.
Loss of consciousness is known as coma. It is caused by hemorrhage in
the brain, by profound exhaustion, or may result from a saturation of
the system with the poison of some disease. Coma may follow upon
cerebral depression, which occurs as a secondary state of inflammation
of the brain.
Where the sensibility of a part is increased the condition is known as
hyperesthesia, and where it is lost--that is, where there is no feeling
or knowledge of pain--the condition is known as anesthesia. The former
usually accompanies some chronic disease of the spinal cord or the
earlier stages of irritation of a nerve trunk. Hyperesthesia is
difficult to detect in a nervous, irritable animal, and sometimes even
in a horse of less sensitive temperament. An irritable, sensitive spot
may be found surrounded by skin that is not sensitive to pressure. This
is sometimes a symptom of beginning of inflammation of the brain.
Anesthesia occurs in connection with cerebral and spinal paralysis,
section of a nerve trunk leading to a part, in severe mental depression,
and in narcotic poisoning.
URINARY AND SEXUAL ORGANS.
In considering the examination of the urinary and sexual organs we may
consider, at the beginning, a false impression that prevails to an
astonishing extent. Many horsemen are in the habit of pressings upon the
back of a horse over the loins or of sliding the ends of the fingers
along on either side of the median line of this region. If the horse
depresses his back it is at once said "his kidneys are weak." Nothing
could be more absurd or further from the truth. Any healthy horse--any
horse with normal sensation and with a normally flexible back--will
cause it to sink when manipulated in this way. If the kidneys are
inflamed and sensitive, the back is held more rigidly and is not
depressed under this pressure.
To examine the kidneys by pressure the pressure should be brought to
bear over these organs. The kidneys lie beneath the ends of the
transverse processes of the vertebrae of the loins and beneath the
hind-most ribs. If the kidneys are actually inflamed and especially
sensitive, pressure or light blows applied here may cause the horse to
shrink.
The physical examination of the sexual and generative organs is made in
large part through the rectum, and this portion of the examination
should be carried out by a veterinarian only. By this means it is
possible to discover or locate cysts of the kidneys, urinary calculi in
the ureters, bladder, or upper urethra, malformations, and acute
inflammations accompanied by pain. The external genital organs are
swollen, discolored, or show a discharge as a result of local disease or
from disease higher in the tract.
The manner of urinating is sometimes of considerable diagnostic
importance. Painful urination is shown by frequent attempts, during
which but a small quantity of urine is passed; by groaning, by
constrained attitude, etc. This condition comes from inflammation of the
bladder or urethra, urinary calculi (stones of the bladder or urethra),
hemorrhage, tumors, bruises, etc. The urine is retained from spasms of
the muscle at the neck of the bladder, from calculi, inflammatory
growths, tumors, and paralysis of the bladder.
The urine dribbles without control when the neck of the bladder is
weakened or paralyzed. This condition is seen after the bladder is
weakened from long-continued retention and where there is a partial
paralysis of the hind quarters.
Horses usually void urine five to seven times a day, and pass from 4 to
7 quarts. Disease may be shown by increase in the number of voidings or
of the quantity. Frequent urination indicates an irritable or painful
condition of the bladder or urethra or that the quantity is excessive.
In one form of chronic inflammation of the kidneys (interstitial
nephritis) and in polyuria the quantity may be increased to 20 or 30
quarts daily. Diminution in the quantity of urine comes from profuse
sweating, diarrhea, high fever, weak heart, diseased and nonsecreting
kidneys, or an obstruction to the flow.
The urine of the healthy horse is a pale or at times a slightly reddish
yellow. The color is less intense when the quantity is large, and is
more intense when the quantity is diminished. Dark-brown urine is seen
in azoturia and in severe acute muscular rheumatism. A brownish-green
color is seen in jaundice. Red color indicates admixture of blood from a
bleeding point at some part of the urinary tract, usually in the
kidneys.
The urine of the healthy horse is not clear and transparent. It contains
mucus, which causes it to be slightly thick and stringy, and a certain
amount of undissolved carbonates, causing it to be cloudy. A sediment
collects when the urine is allowed to stand. The urine of the horse is
normally alkaline. If it becomes acid the bodies in suspension are
dissolved and the urine is made clear. The urine may be unusually cloudy
from the addition of abnormal constituents, but to determine their
character a chemical or microscopic examination is necessary. Red or
reddish flakes or clumps in the urine are always abnormal, and denote a
hemorrhage or suppuration in the urinary tract.
The normal specific gravity of the urine of the horse is about 1.040. It
is increased when the urine is scanty and decreased when the quantity is
excessive.
Acid reaction of the urine occurs in chronic intestinal catarrh, in high
fever, and during starvation. Chemical and microscopic tests and
examinations are often of great importance in diagnosis, but require
special apparatus and skill.
Other points in the examination of a sick horse require more discussion
than can be afforded in this connection, and require special training on
the part of the examiner. Among such points may be mentioned the
examination of the organs of special sense, the examination of the
blood, the microscopic examination of the secretions and excretions,
bacteriological examinations of the secretions, excretions, and tissues,
specific reaction tests, and diagnostic inoculation.
FUNDAMENTAL PRINCIPLES OF DISEASE.
By RUSH SHIPPEN HUIDEKOPER, M. D., VET.
[Revised by Leonard Pearson, B. S., V. M. D.]
ANIMAL TISSUES.
The nonprofessional reader may regard the animal tissues, which are
subject to inflammation, as excessively simple structures, as similar,
simple, and fixed in their organization as the joists and boards which
frame a house, the bricks and iron coils of pipe which build a furnace,
or the stones and mortar which make the support of a great railroad
bridge. Yet while the principles of structure are thus simple, for the
general understanding by the student who begins their study the complete
appreciation of the shades of variation, which differentiate one tissue
from another, which define a sound tendon or a ligament from a fibrous
band--the result of disease filling in an old lesion and tying one organ
with another--is as complicated as the nicest jointing of Chinese
woodwork, the building of a furnace for the most difficult chemical
analysis, or the construction of a bridge which will stand for ages and
resist any force or weight.
All tissues are composed of certain fundamental and similar elements
which are governed by the same rules of life, though at first glance
they may appear to be widely different. These are (a) amorphous
substances, (b) fibers, and (c) cells.
(a) Amorphous substances may be in liquid form, as in the fluid of the
blood, which holds a vast amount of salts and nutritive matter in
solution; or they may be in a semiliquid condition, as the plasma which
infiltrates the loose meshes of connective tissue and lubricates the
surface of some membranes; or they may be in the form of a glue or
cement, fastening one structure to another, as a tendon or muscle end to
a bone; or, again, they hold similar elements firmly together, as in
bone, where they form a stiff matrix which becomes impregnated with lime
salts. Amorphous substances, again, form the protoplasm or nutritive
element of cells or the elements of life.
(b) Fibers are formed of elements of organic matter which have only a
passive function. They can be assimilated to little strings, or cords,
tangled one with another like a mass of waste yarn, woven regularly like
a cloth, or bound together like a rope. They are of two kinds--white
connective tissue fibers, only slightly extensible, pliable, and very
strong, and yellow elastic fibers, elastic, curly, ramified, and very
dense. These fibers once created require the constant presence of fluids
around them in order to retain their functional condition, as a piece of
harness leather demands continual oiling to keep its strength, but they
undergo no change or alteration in their form until destroyed by death.
(c) Cells, which may even be regarded as low forms of life, are masses
of protoplasm or amorphous living matter, with a nucleus and frequently
a nucleolus, which are capable of assimilating nutriment or food,
propagating themselves either into others of the same form or into fixed
cells of another outward appearance and different function but of the
same constitution. It is simply in the mode of the grouping of these
elements that we have the variation in tissues, as (1) loose connective
tissue, (2) aponeurosis and tendons, (3) muscles, (4) cartilage, (5)
bones, (6) epithelia and endothelia, (7) nerves.
(1) Loose connective tissue forms the great framework, or scaffolding,
of the body, and is found under the skin, between the muscles
surrounding the bones and blood vessels, and entering into the
structures of almost all the organs. In this the fibers are loosely
meshed together like a sponge, leaving spaces in which the nutrient
fluid and cells are irregularly distributed. This tissue we find in the
skin, in the spaces between the organs of the body where fat
accumulates, and as the framework of all glands.
(2) Aponeurosis and tendons are structures which serve for the
termination of muscles and for their contention, and for the attachment
of bones together. In these the fibers are more frequent and dense, and
are arranged with regularity, either crossing each other or lying
parallel, and here the cells are found in minimum quantity.
(3) In the muscles the cells lie end to end, forming long fibers which
have the power of contraction, and the connective tissue is in small
quantity, serving the passive purpose of a band around the contractile
elements.
(4) In cartilage a mass of firm amorphous substance, with no vascularity
and little vitality, forms the bed for the chondroplasts, or cells of
this tissue.
(5) Bone differs from the above in having the amorphous matter
impregnated with lime salts, which gives it its rigidity and firmness.
(6) Epithelia and endothelia, or the membranes which cover the body and
line all its cavities and glands, are made up of single or stratified
and multiple layers of cells bound together by a glue of amorphous
substance and resting on a layer composed of fibers. When the membrane
serves for secreting or excreting purposes, as in the salivary glands or
the kidneys, it is usually simple; when it serves the mechanical purpose
of protecting a part, as over the tongue or skin, it is invariably
multiple and stratified, the surface wearing away while new cells
replace it from beneath.
(7) In nerves, stellate cells are connected by their rays to each other,
or to fibers which conduct the nerve impressions, or they act as
receptacles, storehouses, and transmitters for them, as the switch-board
of a telephone system serves to connect the various wires.
All these tissues are supplied with blood in greater or less quantity.
The vascularity depends upon the function which the tissue is called
upon to perform. If this is great, as in the tongue, the lungs, or the
sensitive part of the hoof, a large quantity of blood is required; if
the labor is a passive one, as in cartilage, the membrane over the
withers, or the tendons of the legs, the vessels only reach the
periphery, and nutrition is furnished by imbibition of the fluids
brought to their surface by the blood vessels.
Blood is brought to the tissues by arterioles, or the small terminations
of the arteries, and is carried off from them by the veinlets, or the
commencement of the veins. Between these two systems are small, delicate
networks of vessels called capillaries, which subdivide into a veritable
lacework so as to reach the neighborhood of every element.
In health the blood passes through these capillaries with a regular
current, the red cells or corpuscles floating rapidly in the fluid in
the center of the channel, while the white or ameboid cells are
attracted to the walls of the vessels and move very slowly. The supply
of blood is regulated by the condition of repose or activity of the
tissue, and under normal conditions the outflow exactly compensates the
supply. The caliber of the blood vessels, and consequently the quantity
of blood which they carry, is governed by nerves of the sympathetic
system in a healthy body with unerring regularity, but in a diseased
organ the flow may cease or be greatly augmented. In health a tissue or
organ receives its proper quantity of blood; the nutritive elements are
extracted for the support of the tissue and for the product, which the
function of the organ forms. The force required in the achievement of
this is furnished by combustion of the hydrocarbons and oxygen brought
by the arterial blood, then by the veins this same fluid passes off,
less its oxygen, loaded with the waste products, which are the result of
the worn-out and disintegrated tissues, and of those which have
undergone combustion. The foregoing brief outline indicates the process
of nutrition of the tissues.
Hypernutrition, or excessive nutrition of a tissue, may be normal or
morbid. If the latter, the tissue becomes congested or inflamed.
CONGESTION.
Congestion is an unnatural accumulation of blood in a part. Excessive
accumulation of blood may be normal, as in blushing or in the red face
which temporarily follows a violent muscular effort, or, as in the
stomach or liver during digestion, or in the lungs after severe work,
from which, in the latter case, it is shortly relieved by a little rapid
breathing. The term congestion, however, usually indicates a morbid
condition, with more or less lasting effects. Congestion is active or
passive. The former is produced by an increased supply of blood to the
part, the latter by an obstacle preventing the escape of blood from the
tissue. In either case there is an increased supply of blood, and as a
result increased combustion and augmented nutrition.
ACTIVE CONGESTION.
Active congestion is caused by--
(1) _Functional activity._--Any organ which is constantly or excessively
used is habituated to hold an unusual quantity of blood; the vessels
become dilated; if overstrained the walls become weakened, lose their
elasticity, and any sudden additional quantity of blood engorges the
tissues so that they can not contract, and congestion results. Example:
The lungs of a race horse, after an unusual burst of speed or severe
work, in damp weather.
(2) _Irritants._--Heat and cold, chemical or mechanical. Any of these,
by threatening the vitality of a tissue, induce immediately an augmented
flow of blood to the part to furnish the means of repair--a hot iron,
frostbites, acids, or a blow.
(3) _Nerve influence._--This may produce congestion either by acting on
the part reflexly or as the result of some central nerve disturbance
affecting the branch which supplies a given organ.
(4) _Plethora and sanguinary temperament._--Full-blooded animals are
much more predisposed to congestive diseases than those of a lymphatic
character or those in an anemic condition. The circulation in them is
forced to all parts with much greater force and in large quantities. A
well-bred, full-blooded horse is much more subject to congestive
diseases than a common, coarse, or old, worn-out animal.
(5) _Fevers._--In fever the heart works more actively and forces the
current of blood more rapidly; the tissues are weakened, and it requires
but a slight local cause at any part to congest the structures already
overloaded with blood. Again, in certain fevers, we find alteration of
the blood itself, rendering it less or more fluid, which interferes with
its free passage through the vessels and induces a local predisposition
to congestion.
(6) _Warm climate and summer heat._--Warmth of the atmosphere relaxes
the tissues; it demands of the animals less blood to keep up their own
body temperature, and the extra quantity accumulates in the blood-vessel
system. It causes sluggishness in the performance of the organic
functions, and in this way it induces congestion, especially of the
internal organs. So we find founders, congestive colics, and staggers
more frequent in summer than in winter.
(7) _Previous congestion._--Whether the previous congestion of any organ
has been a continuous normal one--that is, a repeated functional
activity--or has been a morbid temporary overloading, it always leaves
the walls of the vessels weakened and more predisposed to recurrent
attacks from accidental causes than are perfectly healthy tissues. Thus
a horse which has had a congestion of the lungs from a severe drive is
liable to have another attack from even a lesser cause.
The alterations of congestion are distention of the blood vessels,
accumulation of the cellular elements of the blood in them, and effusion
of a portion of the liquid of the blood into the fibrous tissues which
surround the vessels. When the changes produced by congestion are
visible, as in the eye, the nostril, the mouth, the genital organs, and
on the surface of the body in white or unpigmented animals, the part
appears red from the increase of blood; it becomes swollen from the
effusion of liquid into the spongelike connective tissues; it is at
times more or less hot from the increased combustion; the part is
frequently painful to the animal from pressure of the effusion on the
nerves, and the function of the tissue is interfered with. The secretion
or excretion of glands may be augmented or diminished. Muscles may be
affected with spasms or may be unable to contract. The eyes and ears may
be affected with imaginary sights and sounds.
PASSIVE CONGESTION.
Passive congestion is caused by interference with the return of the
current of blood from a part.
Old age and debility weaken the tissues and the force of the
circulation, especially in the veins, and retard the movement of the
blood. We then see horses of this class with stocked legs, swelling of
the sheath of the penis or of the milk glands, and of the under surface
of the belly. We find them also with effusions of the liquid parts of
the blood into the lymph spaces of the posterior extremities and organs
of the pelvic cavity.
Tumors or other mechanical obstructions, by pressing on the veins,
retard the flow of blood and cause it to back up in distal parts of the
body causing passive congestion.