The number of respirations in a given time may afford valuable
indications in the horse but in the other domestic animals variation in
number imports little. In the ox for instance, the respirations in
health may vary from twelve to eighty per minute, according to the heat
of the cowhouse, the plentitude of the abdominal organs and other
circumstances. So in the sheep and dog slight causes, quite compatible
with health, may cause the breathing to become short, panting and
hurried.
The young horse breathes ten to twelve times per minute, the adult
animal nine to ten. Any excitement accelerates. A horse walked a few
hundred yards had the respirations increased from ten to twenty-eight
per minute; after trotting five minutes they numbered fifty-two; after
galloping five minutes sixty-five.
=Hurried breathing= occurring independently of exercise, heat of the
atmosphere, or distension of the abdomen, is indicative of fever,
especially if associated with rapid pulse and increased heat of the
body.
Infrequent respiration appears in certain brain diseases in the
intervals between the more violent paroxysms, also in poisoning by opium
and other narcotics. =Tardy or slow respirations= differ from those last
noticed in the act occupying a longer time. In infrequent breathing the
act may be short, though there are few respirations in the minute. This
is likewise seen in brain diseases and sometimes in broken wind. In the
last case there is =double action of the flank=, each act of expiration
being effected by two successive and distinct elevations of the flank.
=Quick breathing= in which the act occupies only a short time is usually
abruptly cut off, the inspiration terminating by a catch or jerk. It is
significant of the early stage of pleurisy, and arises from the desire
to avoid the pain attendant on the rubbing together of the inflamed
surfaces during deep inspirations. It is further seen in tetanus,
peritonitis, pericarditis and pleurodynia.
=Deep breathing= with great lifting of the flanks and loins is
characteristic of water in the chest, and consequent inability to
inflate the lungs.
=Labored breathing=, which is at once hurried, deep, and without
intermission, is seen in severe laryngitis, croup, capillary bronchitis,
and pneumonia, in all cases alike from the difficulty experienced in
introducing into the lungs the requisite amount of air. It is especially
marked in double pneumonia, pleuro-pneumonia, complicated with effusion
in the chest, and in old standing _broken wind_ with dilatation of the
right heart.
In all such cases where there is much interference with the æration of
blood, whether from obstruction to the circulation of blood or a
hindrance to the introduction of air, the horse invariably stands. The
fact that he has lain down may be taken as an indication that
improvement has taken place. The peculiarity is due to the sharp outline
of the horse’s sternum inferiorly so that in lying down he is compelled
to rest on his side and the whole weight of the body tends to compress
the chest. In the ox, sheep, pig and dog, which can rest on the sternum,
breathing can be carried on with comparative ease in the recumbent
position, and these animals accordingly do not necessarily stand except
in very extensive and violent affections of the chest.
The occurrence of a short inspiration suddenly checked and a prolonged
expiration characterizes pleurisy, the check to the inspiratory act
being because of the pain caused by dilating the thorax.
The double lifting of the flank in expiration:—the act appearing to be
performed by two distinct and successive acts is one of the most
prominent symptoms of broken wind, but is not peculiar to this disorder.
In the horse it exists in chronic bronchitis, dilatation of the right
heart, old standing hydrothorax, and diaphragmatic hernia. It is further
frequent in the acute diseases of the chest. In oxen it accompanies
pulmonary emphysema, pulmonary consumption, dilatation of the heart,
foreign bodies in the heart, and dropsy of the pericardium.
If accompanied by clear resonance over the chest, a permanent wheezing
noise heard over the ribs, and the small, weak wheezy cough, it
indicates emphysema (broken wind). If with strong impulse of the heart
against the ribs behind the elbows, venous pulse in the jugulars, and
modification of the second sound of the heart, it bespeaks cardiac
dilatation or other heart disease. If with paroxysmal cough, white curdy
nasal discharge and harsh rasping sounds heard at the lower part of the
trachea or along the upper part of the lungs it betrays chronic
bronchitis.
RELATIVE POSITION OF THE LUNGS, HEART AND OTHER ORGANS IN THE DIFFERENT
DOMESTIC ANIMALS.
Relative positions of thoracic organs. Diaphragm, heart, lung, in
horse, ox, sheep, pig, dog. Palpitation.
The _chest_ is that portion of the trunk closed in on each side by the
ribs, above by the bones of the back, below by the breast bone, and
behind by the diaphragm. It forms thus a cone flattened from side to
side anteriorly, and with its base, represented by the diaphragm which
slopes obliquely from above downward and forward and bulges forward in
the centre to a greater or less extent according to the plenitude of the
stomach and bowels. It results from this arrangement of the diaphragm
that a very thin layer of lung only reaches to the posterior part of the
chest, and that beneath this are solid and hollow abdominal organs which
modify the results of physical examination.
In the =Horse= the anterior third of the chest is covered laterally by
the bulky and muscular shoulders so that it cannot be satisfactorily
examined. In the median line of the chest, at a point corresponding to
the third, fourth, fifth and sixth intercostal spaces, is lodged the
heart. It deviates slightly to the left side below and by virtue of a
notch in the lower border of the lung is enabled here to reach the
surface and its beats may be felt by the hand laid on the side of the
chest just behind the left elbow.
In the =Horse= the diaphragm is attached by its outer border to the last
rib, and to the lower ends of all the asternal ribs, and the extremity
of the breast bone. A thin layer of lung accordingly extends to between
the two last ribs superiorly and down to near the lower end of the
asternal ribs. The subjacent abdominal organs are arranged as
follows:—_On the left side_, and counting from below, the large
intestines (double colon), the stomach and spleen and a portion of the
left lobe of the liver:—_on the right side_, below, the large
intestines, above, the liver and pancreas. Of these the stomach and
intestines frequently contain gases, while the liver by its solidity
gives a special solid character to the right posterior part of the
chest. The spleen is too deeply situated to affect much the results of a
physical examination. The greatest substance of lung is between the
upper and middle thirds of the thorax. The anterior third is
inaccessible on account of the shoulders, but more than usual may be
reached by raising the fore limb and drawing it forcibly forwards. The
space between the third and seventh ribs is occupied by the solid mass
of the heart, which especially modifies the result of physical
examination on the left side where a notch in the lung allows it to
approach the surface.
In the =ox= the diaphragm is only attached to the last rib for two or
three inches at its upper extremity; it is fixed to the second last rib
as far down as about one-third of its length; thereafter it is attached
in succession to the middle third of the third last, to the lower third
of the fourth last, to the lower ends of the next two in succession and
to the sternum. The result is that the lungs do not extend so far back
relatively to the ribs as they do in the horse. They are virtually
absent from the last intercostal space, present only in the upper third
of the second last, in the upper two-thirds of the third last and reach
the lower third only in the space between the ninth and tenth ribs. The
paunch alone occupies the space beneath the asternal ribs on the left
side, and the liver and the solid mass of the omasum and abomasum that
beneath the right. The shoulders in fat improved beef breeds absolutely
prevent examination of the anterior third of the chest, though in thin
animals and dairy breeds and scrubs more of this may be exposed by
raising the fore limb than in the horse. The heart corresponding in
position to the third, fourth and fifth intercostal spaces is more
completely covered by lung tissue and does not strike the left side so
forcibly as in the horse.
In the =sheep= the lung extends to the last intercostal space, nearly as
far as its lower end and the heart is covered on the left side as well
as on the right by lung tissue. The shoulder is very movable and unless
in very fat animals allows of an examination of the greater part of the
anterior third of the chest.
In the =pig= fat and indocility combine to defeat our purpose in
examination of the chest. If these can be obviated it is well to know
that the diaphragm is attached to the upper two-thirds of the last rib,
and to the next three in front above their lower third.
In the =dog= the diaphragm is attached to the upper two-thirds of the
last rib, to the lower third of the next and to the lower ends of the
two following and to the breast bone. The shoulders are so mobile and
the breast bone so thin that nearly all the chest may be satisfactorily
examined. The heart, covered on both sides by lung, lies nearly
horizontally on the breast bone, through which its position and bulk may
be clearly made out by percussion.