All animals liable. Causes, pleurisy, obstruction to pulmonary or
intercostal veins, heart disease, Bright’s disease, anæmia, parasitic
or otherwise. Effusion reddish gray or clear straw color, inflammatory
and dropsical. Symptoms, troubles of respiration, as a secondary
disease complicated by dropsies elsewhere, signs of hydrothorax
without fever, shedding of hair. Treatment, diuretic, tonic,
derivative, thoracentesis, trochar and cannula or aspiration, point of
election for puncture, method, asepsis, drainage by aspirator, or into
an antiseptic solution, eligible cases, dangers attending
thoracentesis, shock, rupture of false membranes and lung, infection
of pleura, injection of antiseptics.
_Hydrothorax_ or _water in the chest_ is common to all domestic animals.
It is as we have seen one of the most ordinary results of _pleurisy_,
and may persist long after that disease has disappeared. It likewise
occurs independently of inflammation as a dropsical effusion. Thus when
the return of blood by the bronchial, pulmonary or intercostal veins, is
hindered by any cause such as tumors in the bronchial glands or
subvertebral region a passive effusion may take place through the coats
of the vessels. In imperfection of the mitral valves the regurgitation
of blood in the pulmonary veins during each cardiac systole equally
causes such transudation. Chronic disease of the kidneys (Bright’s
disease) with the retention of effete and injurious materials in the
blood leads to dropsy of the chest as in other parts of the body. Again
in many debilitated conditions parasitic and otherwise, with a tendency
to general dropsy the chest participates and a collection of fluid takes
place in the pleuræ.
The nature of the contained fluid will vary according to the conditions
in which it has been effused. If the result of inflammation there are
the different stages already indicated: _first_, of a yellow citrine
color or red from contained blood; _second_, grayish and muddy either
from contained pus or other changes taking place in the fluid; and
_third_, clear limpid and translucent as seen in the later stages. If
merely a dropsical effusion the fluid is watery clear and translucent or
with a slight straw color. The inflammatory effusion contains fibrine or
fibrinogenous elements, is associated with the formation of false
membranes, and though it may remain fluid so long as it is retained in
the chest, it coagulates rapidly when withdrawn. The dropsical effusion
rarely contains fibrine, and then only in very small amount, and it does
not coagulate when drawn off from the chest. The inflammatory effusion
usually contains a greater proportion of common salt, phosphates or
albumen than exist in the blood, and floating granules, particles and
cell forms, none of which conditions characterize the dropsical
effusions. The most prominent feature of the inflammatory effusions is
thus seen to be their power of coagulation, by virtue of the contained
fibrine, when exposed to the air.
_Symptoms._ When a sequel of pleurisy it is manifested by the symptoms
already mentioned under that head as indicating the occurrence of
effusion.
The dropsical cases may come on rapidly and present all the signs of
troubled respiration together with the results of auscultation and
percussion that characterize rapid inflammatory effusion but without the
fever and acute symptoms of pleurisy. More usually it comes on
insidiously, the lung accommodates itself to the gradual increase of the
fluid and it is only when the accumulation has become excessive that the
symptoms become prominent. In heart or kidney disease the filling of the
legs and infiltrations of the eyelids and of the skin beneath the chest
and abdomen are precursors or early concomitants of the disease, but in
all cases the accumulation in the chest is to be measured by the height
of the line of dulness on percussion and the extent of chest surface
giving forth no respiratory murmur on auscultation. As the liquid rises
on both sides of the chest, as it always does in such cases in the
horse, the breathing becomes short and labored, being chiefly effected
by the action of the diaphragm and the flanks—the ribs moving only
slightly. The nostrils are widely dilated with each breath. The
previously existing want of vigor and energy, the weak pulse, the poor
appetite and the pallor of the mucous membranes become aggravated; the
animal becomes very weak and prostrate, the loins insensible, the
permanently tucked up flanks labor tumultuously, the loins rise in
inspiration, the face is pinched and haggard, the eyeballs glazed and
protruding, and death is preceded by the same general symptoms as in
rapid effusion after pleurisy. A prominent feature of this, as of all
dropsical affections, and one usually seen in the hydrothorax of
inflammation as well, is the ease with which, even at an early stage of
the disease, the long hairs of the mane and tail may be pulled out. In
many cases they come out in handfulls when the comb or the fingers are
passed through them.
_Treatment._ The treatment must be of the actively diuretic kind
recommended for the effusion of pleurisy. It is modified however in one
respect. The inflammatory action having subsided or nearly so and the
condition being now essentially one of weakness a free use of tonics is
demanded. Many a patient dies in such circumstances from the actively
depletive treatment to which it has been subjected and the want of
attention to its need of generous diet and other support. The agents
prescribed for the advanced stage of pleurisy may be given, or the
digitalis or other diuretics and bitters may be combined with iodide of
potassium in one or two drachm doses, the amount being apportioned to
the strength of the animal. Iron in the form of sulphate, perchloride or
iodide may be freely given combined with gentian, quassia, or other
vegetable tonic, and above all a liberal and easily digested diet must
be allowed. Good will sometimes result from repeated applications of
strong iodine ointment to the sides with active friction.
When the condition is dependent on disease of the heart, kidney or other
organ, these must be attended to according to their special
requirements.
Disconnected from such complications hydrothorax will often give way to
an active treatment similar to that indicated above. In some cases
however our only hope of even temporarily prolonging life lies in the
operation for drawing off the fluid.
=Tapping the chest= or as it is technically called =thoracentesis= or
=paracentesis thoracis= has proved sufficiently successful in the lower
animals to warrant its continuance in cases that resist other modes of
treatment. It is highly probable that the larger proportion of
unsuccessful cases is due in great part to the hopelessly advanced stage
at which it is often had resort to, to the insufficient precautions
adopted in its performance, and to the want of appropriate dietetic and
medicinal treatment. Dr. Bowditch’s treatment by _paracentesis_ saved in
the human subject at the rate of about two patients in five and we ought
by availing of similar precautions to reach the same standard.
The cannula employed in veterinary practice is a silver tube two inches
in length, a quarter of an inch in diameter and furnished with a shield
of the same metal at one end. The trochar by which it is introduced is
of steel or brass. To carry out Dr. Bowditch’s system the operator must
supply himself with a syringe of a somewhat smaller bore and an
intermediate brass piece of a size adapted to fit accurately into the
cannula and supplied with a stopcock. By an instrument of this kind the
fluid can be drawn off by means of the syringe without any risk of the
introduction of ærial germs which always tend to induce suppuration and
even a putrefactive decomposition in the contained fluid.
The point selected to operate on is, in the horse, ox or dog, in front
of the anterior border of the ninth rib, at its lower end or close to
its union with the cartilage. The point of the trochar should be
directed slightly upward and forward to avoid the possibility of
injuring the diaphragm. The skin is first rendered aseptic by shaving,
followed by a thorough soapy wash and a free use of mercuric chloride
solution (1:500). It is then pricked with a lancet, then drawn aside
that the wounds in the skin and muscles may not correspond after the
cannula has been withdrawn. The trochar is then pushed steadily through
the intercostal space till all obstruction has been overcome, when it
may be concluded that the pleural sac has been reached. The trochar is
now withdrawn and the fluid allowed to flow from the cannula until there
is presumably some risk of the introduction of air, when the brass piece
is to be applied and the remainder drawn off with the syringe or
aspirator. As a substitute for the aspirator a caoutchouc tube, eighteen
inches long, put on the cannula or needle and having its lower end
plunged in a solution of boric acid will prevent the entrance of germs.
A prob has often to be introduced to prevent plugging of the cannula by
floating false membranes, and a new puncture in a different place may be
necessary. In the case of excessive accumulation it is often advisable
to draw it off at two operations, as recommended in large abscess of the
pleura and for the same reasons. The need for such a precaution will be
understood when it is stated that in bad cases the chest contains as
much as six or seven ordinary stable bucketfuls of the liquid. If,
however, it is limited in amount it may be all withdrawn at once.
The most successful cases in the horse have been upon young, vigorous
animals, from four to eight years old, during the first month of
illness, and where the pleurisy has been confined to one side.
Dr. Bowditch lays down the following rules for the adoption of
paracentesis in man (_Clinical Medicine_, by Prof. W. T. Gairdner):—
“I now never operate unless I find some distension or rounding out of
the chest, and filling up of some of the intercostal spaces, so that the
chest presents a uniform curve, and not alternate depressions and
elevations as in the healthy chest. I operate under the following
circumstances when I feel certain there is fluid:
“1. When there is _severe permanent dyspnœa_—orthopnœa—however acute the
disease if I find fluid filling the pleural cavity, or nearly filling
it.
“2. When there are occasional attacks of orthopnœa threatening death,
even if there be not sufficient to fill more than half of the cavity. If
the fluid seems to be the cause of the dyspnœa I operate, because
occasionally I have lost a patient while waiting for more extensive
physical signs. This rule I apply to acute and chronic cases.
“3. I use the trochar after three or four weeks of ineffectual
treatment, without any absorption being produced.
“4. In chronic idiopathic hydrothorax, a latent pleurisy with simply
physical signs to indicate _extensive_ effusion, but when the rational
signs are either very slight or none at all save a general malaise and
weakness.”
The use of iodide of potassium and vegetable and mineral tonics must be
perseveringly employed and the strength further supported by a generous
diet, to secure the animal against the dangers of extreme prostration,
of suppuration, or other undesirable conditions of the exuded product.
Among the dangers attending thoracentesis are fainting as a result of
shock on the sudden withdrawal of so much liquid, rupture of the false
membranes, and even of the enclosed lung tissue or of blood vessels,
under the sudden expansion of the partially collapsed lung confined by
the investing false membrane, and the introduction of pus or septic
germs into the pleural cavity. To obviate the first named dangers tight
bands (circingles) around the chest will give support and limit sudden
expansion. In case of excess of liquid the withdrawal of one-half or
two-thirds at a time will allow opportunity for accommodation.
Hæmorrhage may be met by the internal use of chloride, sulphate or
nitrate of iron, matico, hamamelis or tannic acid, and a weak solution
of boric acid or other antiseptic agent may even be injected in small
amount into the pleural cavity.
In obstinate and chronic cases the injection of a weak solution of
iodine and iodide of potassium is often of service. In other cases a
normal chloride of sodium solution (previously sterilized) may be
introduced as soon as a partial evacuation causes uneasiness, and by a
succession of such evacuations and injections the residuum liquid may be
rendered clear and largely aseptic on a single occasion.
In the smaller animals the selection of the most dependent part for
insertion of the trochar is not so essential, as the body may be turned
to facilitate the drainage.
On completion of the operation the wound may be again treated
antiseptically and coated with aristol or collodion.