Third, the systolic and diastolic sounds may increase, diminish, or be succeeded by other sounds indicative of disease hereafter described. Pericarditis—Dropsy of the Heart DEFINITION.—Inflammation of the fibro-serous membrane which invests the heart, causing the effusion of a serous fluid. It occurs as a primary affection and as a complication in Influenza, Rheumatism and other constitutional diseases. CAUSES.—When met with in an idiopathic form, which is very rare, it may depend upon exposure to damp, cold, changes of temperature, and those unhealthy conditions which also cause acute diseases of the respiratory organs. It may also arise from a sudden change from low, to rich heating food, or from the field to a hot stable. But it usually occurs as an accompaniment of Pleurisy or Rheumatism. SYMPTOMS.—The horse stands quiet, showing signs of pain and anguish, with sunken head, anxious expression in the face, dilated nostrils, frequent (100 to 120), wiry, and sometimes IRREGULAR or intermittent PULSE, and general intense fever. The breathing is also accelerated (36) and difficult, and is accompanied by a movement of the flank similar to that seen in broken wind, and by a deep depression along the margin of the costal cartilages. In the early stages, pressure on the left side, and smart percussion in the region of the heart, cause flinching and expression of pain; and auscultation, _before exudation has taken place_, reveals friction—_to and fro_—sounds. These sounds are, however, not uniformly present in this disorder, nor is their presence an unquestionable proof of its existence, for similar sounds may be do to pleural disease, the latter being characterized by synchronism with the respiratory movements. The friction sounds are therefore of little value, except as concurrent with other symptoms. They also cease when exudation or adhesion has taken place; then the heart’s beats are muffled. In the later stages, the heart, which at first palpitates, soon becomes fluttering and uncertain in its beat, conveying a peculiar pulsation to the hand, not easily to be described. No impulse can be felt when the effusion is considerable. Percussion gives a dull sound over the region of the heart, but not so in other parts of the chest, where the respiratory and bronchial sounds may be heard, thus distinguishing Hydrops Percardii from Hydrothorax. The breathing gradually becomes more distressing, and movement aggravates the distress; the pulse more feeble and even imperceptible at the jaw; the ears and legs cold; the legs, sheath, chest, abdomen, etc., œdematous; and the general wasting rapid till death ensues.