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.