Active and passive congestions. Congestion of incipient pneumonia.
Congestion of over-exertion. Causes, lack of condition, fat, plethora,
gorged stomach, hot weather, cold rains, cold baths, infectious
diseases. Symptoms, dilated nostrils, labored breathing, deep lifting
of flanks, panting, pendent head, staring, fixed, bloodshot eyes,
pale—later dark red nasal mucosa, rapid pulse, palpitating heart, fine
crepitation, cold limbs, tremors, perspiration, obstinate standing,
till unable, blood from nose. Fulminant cases. Exposure cases. Course.
Termination. Resolution. Lesions, lungs black, gorged, do not
crepitate nor collapse, lessened buoyancy, cut surface, compressed
bronchioles and alveoli, right heart and veins gorged, blood black,
semi-liquid, petechiæ. Nature. Not yet inflammatory, blood
engorgement, no cell proliferation, migration, non-exudation,
pulmonary vaso-motor paresis, effect of blood pressure, of peptones,
etc., of exhaustion. Treatment, relieve respiratory muscles,
derivation to surface, stimulants, hot pediluvia and packs, relief of
vascular system, bleeding, heart stimulants, digitalis.
Congestion of the lungs occurs in all animals as the precursor of
inflammation, but as death may occur without the supervention of actual
inflammation a special notice appears to be demanded. The hyperæmia of
the lungs may be seen in two forms, active and passive, the latter form
being secondary to other diseases, such as valvular diseases of the left
heart, by reason of which the blood is forced back on the lungs and
creates mechanical congestion. The active form is a pathological process
developed in the lung itself, and which often proves fatal through
arrest of the circulation through this organ.
_Causes._ The pulmonary congestions preceding pneumonia are due to the
same causes with that disease. The most typical, acute and deadly form
of pulmonary congestion is usually due to _over-exertion in an animal
that is fat and out of condition_. The English hunting field presents
the most typical specimens. A horse that has just left the dealer’s
hands, or that is plethoric, fat, soft and flabby, is ridden over a
heavy country, and though he may perform well for a few miles, he soon
hangs heavily on the bit, slackens his pace, and if not pulled up,
staggers and falls “all of a heap.” A farm horse, taken from grass or
other soft feeding, and entirely out of condition often suffers in the
same way, in going perhaps for the veterinarian in case of urgent colic
in one of its fellows. Cruzel draws attention to similar congestions
from over-exertion in fat cattle, and Trasbot in wild stags and hogs
when beechnuts and acorns were abundant, in pampered family horses and
in plethoric farm animals generally. Excessive heat (heat apoplexy) is
invoked as a cause, and the arrest of hæmatosis and consequent
stagnation in the pulmonary capillaries are undoubtedly accessory
causes, yet the majority of cases, and the most typical and fatal, occur
in the winter season (the hunting season). On the other hand, chills
from rains or cold draughts, especially when heated and exhausted, are
common causes, and the disease often comes on more gradually, attaining
its acme after five or six hours. A horse perspiring after a hard drive
and left to face a cold blast unblanketed, or one plunged by accident
into ice cold water for ten minutes (Trasbot) are examples of this kind.
These cases are ushered in by violent rigors, whereas in those due to
over-exertion this is much less marked and is usually only suggested by
the coldness of surface and extremities. Another condition which
contributes to pulmonary congestion is a full stomach. The plentitude of
the abdominal organs leads to compression of the lungs and hampered
circulation, and when to this is added over-exertion and exhaustion
acute congestion is speedily induced.
Acute congestions are noticed as an accompaniment of other diseases, but
these are mostly either the localization in the lung of a specific
morbid process (anthrax, influenza, distemper, strangles), or it is due
to auto-poisoning, as when the cutaneous transpiration is suppressed by
a coating of glue, or to embolism.
_Symptoms._ In the horse which fails under severe exertion there are the
dilated nostrils, the labored breathing, the deep, almost convulsive
action of the flanks, the hanging on the reins, the slacking of the
pace, the unsteadiness of gait, and lastly the fall. There may now be
noticed the protruded bloodshot eyes, the agonized expression of
countenance, the extended head, the pallor, and later the blueness of
the nasal mucous membrane, the short, panting breathing, accompanied by
a roaring noise alike in inspiration and expiration, and the small,
weak, rapid pulse often imperceptible at the jaw. If the animal has been
stopped short of having fallen, or if he is able to get upon his feet,
he stands with his limbs apart to secure his stability, and with the
elbows turned out to facilitate the expansion of the chest. As the
breathing becomes panting the respirations are less deep, the ribs are
maintained permanently drawn outward, and the flanks rise and fall to a
limited extent only but with great rapidity (eighty to one hundred per
minute). Auscultation may detect at first an increase in the pitch of
the respiratory murmur, and the presence of the finest possible
_crepitation sound_. Soon the murmur decreases uniformly. The
extremities are cold, and in this coldness the general surface to some
extent participates even though it may be covered by perspiration.
Tremors or rigors are present. The heart is felt behind the left elbow
to beat tumultuously. If blood is drawn it flows in a thin, black, tary
stream.
In some cases blood more or less frothy is discharged from the nostrils
as the result of rupture of pulmonary vessels.
In the fulminant cases in =cattle= respiration is rapid, even panting,
wheezing, the expiration attended by a hoarse grunt, sometimes nasal
hemorrhage, great prostration, profuse perspiration, a stupor sets in
and the animal falls and dies, with more or less struggling.
In the cases which develop more slowly, and as the result of cold and
chill whether in horses or cattle, there is dullness, anorexia,
prostration, increasing rapidity and oppression of the breathing, a
small, frequent, hoarse cough, and at first distinct pallor of the
conjunctiva and pituitary mucosa, with more or less trembling. The head
is extended on the neck, toward an open door or window, if available,
until prostration and stupor forbid. The pulse is small, thready, often
almost imperceptible and much accelerated, while the heart beats are
strong, violent, tumultuous. For a time the respiration may be not more
than double the normal rythm, but it tends to more or less rapid
increase with wheezing or stertorous sounds and shaken by trembling of
the respiratory muscles. The nasal discharge is slight and grayish often
with streaks of blood. If it increases the cough becomes looser and
softer. Quite early the respiratory murmur decreases over the whole lung
and a blowing sound from the bronchia or larnyx is heard on the upper
middle third of the chest. This may be complicated by a mucous râle, or
when hæmorrhage has supervened by a loud rattling. Percussion shows a
lack of resonance over the whole lung, not so flat and definitely
circumscribed as in pneumonia but a partial flatness of sound over the
whole chest. In pneumonia a limited area of lung is absolutely
solidified (hepatized) while the remaining lung is practically normal,
whereas in acute congestion often the whole lung is gorged with blood
but for some time no part of it is entirely divested of air.
Another marked feature is the maintenance at first of the normal
temperature with only a slight rise of about 1°. This serves to
distinguish congestion of the lungs from sunstroke (heat anhæmatosis) in
which the temperature usually rises to 108° or 110° F or higher. The
temperature rises however as the disease advances and merges into
pneumonia. Another distinguishing feature from sunstroke is the early
pallor of the mucous membranes which in heat apoplexy are strongly
congested. In congestion they become dark red only with the advance of
the disease and the advent of asphyxia. These features serve also to
distinguish acute pulmonary congestion from contagious fevers, pneumonia
and other inflammations of internal organs.
_Course._ _Termination._ The more acute (fulminant) forms are promptly
fatal. In the exhausted system the lungs have become uniformly gorged
with blood, which can no longer be forced through the capillaries by the
right heart, the heart in turn is overdistended with blood and ceases to
beat and death ensues in a few minutes.
In the less acute cases the patient survives twenty-four hours and
upward, the whole lung not being equally implicated but only certain
lobules, usually the lower, or the congestion, if uniform in all the
lung, being less extreme.
In favorable cases recovery takes place in one or two days. There is a
return of life and appetite, a gradual improvement in pulse and
breathing, the respirations becoming deeper and longer, and in a few
hours all the more violent symptoms may have disappeared. With a more
gradual improvement recovery may still be complete in four or five days.
_Lesions._ When the subject has died suddenly the appearances are
essentially those of uniform engorgement of the pulmonary capillaries
with blood. The general aspect is a dark red, varying from reddish brown
to black, the darkest shades corresponding to circumscribed areas of
actual hæmorrhage. In the worst cases the whole mass may appear like
black currant jelly. The lungs do not collapse when the chest is opened,
they are more or less friable at various points, and different portions
will sink or float in (not on) water, according as it may be more or
less airless. A dark liquid blood exudes freely from the torn or cut
surface. Sections of the lung tissue hardened and examined under the
microscope show the alveoli and bronchioles devoid of exudate, but
having their cavities compressed and obliterated by the pressure of the
swollen mucosa, and its investing blood clot. The heart is overdistended
with fluid blood. In asphyxiated cases the general venous system is
filled with black, liquid blood, and the serosæ spotted with petechiæ.
_Nature._ The nature of this disease is variously understood. It differs
from inflammation in the absence of active cell proliferation, and
migrations of inflammatory exudation, and of fever at all proportionate
to the extent of the lesions. All these may and do supervene if the
patient survives but they are practically absent for a length of time at
the outset. Some attribute it to paresis of the vaso-motor centres for
the lungs, as the result of their over stimulation and of the
retrocession of blood from the chilled surface to the internal organs.
But congestions caused by cutting the cervical branch of the sympathetic
nerve or the sciatic plexus are not marked by a similar blood
extravasation and destruction of tissue. The delicate structure of the
lung tissue and the comparative absence of mechanical support will
account for this in part, the great force of the circulation overloading
the capillaries, under the impulse of the heart so closely adjacent, has
doubtless a certain effect, and the venous nature of the blood thus
forced into the lungs and calculated to arrest all normal function has a
potent influence. If we add to this, for the _over-exertion_ cases, the
sudden advent into the circulatory stream of unchanged peptones and
other ingredients of the portal blood of highly fed and plethoric
animals we find a sufficiently pathogenic combination. In all acute
cases however the adiposity, poor condition and susceptibility to speedy
exhaustion must be given their full share of responsibility.
_Treatment._ Girths, saddles and anything else that may hamper the
movement of the chest must be at once removed and the horse’s head
turned to the wind, an active stimulant given and the legs well rubbed
and loosely flannel bandaged. The nature of the stimulant is of less
consequence than its prompt administration. Two ounces of chloroform, of
sulphuric ether, or of sweet spirits of nitre; half a pint of whisky,
brandy or gin; or a pint of any of the more stimulating wines may be
given, diluted in warm water so as to remove their irritating qualities.
A drink of warm gruel will often go far to restore warmth to the surface
and to unload the overtaxed lungs. Frequent large injections of warm
water have a similar effect. Active hand rubbing of the legs and the
wrapping of them loosely in flannel bandages previously warmed at the
fire is equally valuable. If a roomy, well ventilated, loose box can be
obtained the horse should be led to it gently and a light but warm rug
placed upon the body. Valuable derivation may be obtained from
pediluvia, the feet and legs up to the knees and hocks being put in
buckets of water as hot as the hands can bear, and at the same time
actively rubbed. If this is impossible the legs may be wrapped in
bandages and wet with hot water every few minutes. Or this soothing
derivative agent may be applied as well to the surface of the chest. A
blanket wrung out of hot (nearly boiling) water until it no longer drops
is wrapped round the body and covered up with two or three dry rugs. A
second smaller rug is wrung and placed on the neck and covered by a
sufficiency of hoods to keep in the heat. The legs are meanwhile hand
rubbed and bandaged and the other measures above recommended carried out
to restore the circulation in the surface and extremities. The time
honored practice of bleeding freely from the jugular vein is one of the
most effective means of relieving the overcharged heart and lungs, and
should be resorted to at the earliest possible moment. The blood will at
first flow in a small, dark stream, but as the circulation obtains
relief the jet will increase in volume and the general symptoms will
improve. From four to six quarts may be taken with advantage from an
ordinary horse. This is not a pneumonia but an overloaded heart and
lungs, threatening speedy death and which the abstraction of blood
promptly relieves.
The longer the bleeding is delayed the less effective it is. It should
not supersede the other measures already recommended. There is no real
paradox in both bleeding and giving stimulants in such a case, as the
essential condition is one of weakness, and if the abstraction of blood
has been of use in relieving the clogged heart and lungs, the depression
under which these have labored may be still further overcome by agents
calculated to rouse their suspended vitality.
Trasbot strongly recommends large doses of tartar emetic and iodide of
potassium to reduce the blood pressure in the lungs, an advice which
will be received with hesitation by those who dread the already paretic
condition of the heart. His combination of iodide of potassium with
digitalis will be more confidently resorted to. One drachm of the former
may be given with a half drachm of the latter twice daily.
With the advent of marked fever and other signs of pneumonia, the
treatment for that disease should be resorted to.