An accumulation of serous or sero-fibrinous fluid within the abdominal cavity.
Although an occasional sequel to peritonitis of a chronic type, it is in most instances wholly unconnected with it. Young animals, when pastured on low-lying marsh land through the cold months of winter, and compelled, as some are, to live exclusively on the poor, innutritious herbage which such soil affords, are frequently the subjects of dropsy. The deleterious effects of such living are materially aggravated by the absence of shelter and the cold, wet ground on which they lie. These cases are the result of a disproportion between the fluid and solid constituents of the blood, the ingestion of succulent innutritions food for a long period causing an excess of the former over the latter. In addition to this, a dropsical belly may be the result of chronic disease going on in other organs, as the heart, the liver, and the kidneys. In the heart it indicates some obstructive disorder interfering with the passage of blood from the right to the left side, when the blood is thrown back on the abdominal organs. In the liver and the kidneys it follows upon degenerative changes in their structure. Moreover, any pressure upon or obstruction in the vessels of the liver by which the blood is interrupted in its onward flow may become a cause of abdominal ascites. In old brood-mares it is said to be due to the continued pressure of the gravid uterus upon the large veins of the abdomen.
Until enlargement of the abdomen is apparent, there is little that is diagnostic of fluid accumulating within. The first indication of existing disease has reference to the animal's general condition, the decline of which is marked by dulness, a want of animation, a staring coat, tightness of the skin, and general debility. There will be wasting of the muscles, particularly those along the back, and a diffused swelling may appear beneath the belly. At this time the latter may show more or less general enlargement, and a tendency to drop and become pendulous. On a more minute examination we find the pulse to be small and weak, and a blanching of the visible membranes.
With the progress of abdominal dropsy the limbs not infrequently become enlarged, but vary in size from time to time. Palpitation of the heart may exist either as a sign of great weakness or of heart disease; too much importance, therefore, must not be attached to this symptom until its cause has been satisfactorily made out. We are directed to the liver when the urine becomes loaded with biliary matter and the visible mucous membranes present a yellow discoloration. Indigestion, inappe-tence, a clammy mouth, and bad-smelling faeces are also prominent among the symptoms of dropsy resulting from changes in the liver. The presence of albumen in the urine suggests changes in the kidney. Some idea of the extent of the dropsy or quantity of fluid within the abdominal parietes may be obtained by palpation. We cannot take our patient, unless it is a very small pony, as we would a dog, and with hands on either flank feel the impact of a wave set in motion on one side by a blow on the other, but this test can be applied in a more or less satisfactory manner when an assistant is directed to push the right flank smartly towards the left, on which our own hand is placed, or vice versa.
From the previous remarks, in which we have endeavoured to state some of the many causes of abdominal ascites, it will be apparent that without a correct diagnosis as to the causation of the malady we cannot hope to benefit our patient, only so far as may result from placing him under favourable hygienic conditions.
The half-starved colt will profit by a more liberal dietary, which will restore to the blood its solid constituents, and to this may be added preparations of iron and diuretics. The former help to build up red blood corpuscles and enrich the circulating fluid, while the latter impart functional energy to the kidneys and cause the removal of the effused fluid. Much judgment is needed in the apportionment both of rations and medicines; a sudden change from semi-starvation to plenty being dangerous, and the exhibition of iron having a tendency to occasional constipation, this should be corrected by laxative foods.
In the dropsy of matured and aged animals, where we suspect heart weakness, or where disease of the valves of that organ is made out by auscultation, the treatment will be directed towards regulating the heart's action, and general tonics will be prescribed to strengthen the system. In those patients in which albumen is being voided in the urine, much stimulation of the kidneys with diuretics is to be avoided, and doses of iron, preferably the perchloride in form of tincture, will be found beneficial. When dropsy is associated with liver disease, in which the gland becomes hard and contracted, or other structural changes interfere with the hepatic circulation, there is little to be done. Iodide of potassium in three-dram doses twice a day may be tried, with careful dieting, and a three-ounce dose of sulphate of magnesia now and again to regulate the action of the bowels.
Paracentesis, or what is properly known as "tapping ", is sometimes resorted to, but is of very doubtful value. When the- ordinary measures, as outlined above, wholly fail, it may be assumed that some structural change in one or other of the organs indicated places the case beyond treatment.