204 CLINICAL VETERINARY :MEDICINE AND SURGERY. 



tion. It returned to the seller. The latter (as happens almost always 

 under similar circumstances) after making a number of difficulties 

 consented to an exchange, needless to say on terms advantageous to 

 himself. He succeeded in successively selling this animal to two other 

 persons, who brought it here at intervals of a few weeks. We im- 

 mediately recognised it by its black colour, and by the discharge of 

 saliva which the dealer took means to sustain. 



The history of these two horses shows you how little marked may 

 be the symptoms of chronic pleurisy even when exudate is considerable. 

 In many cases the animal appears perfectly well. All that can be 

 detected in the external appearance is a little dulness, trifling loss of 

 condition, and that peculiar state of the coat expressed by the word 

 "staring." Appetite is usually fair; at times capricious and irregular, 

 hay especially being partly left. The conjunctiva is pale or clay- 

 coloured and infiltrated ; the pulse somewhat rapid, of normal force or 

 rather weak. Fever is always trifling, and the temperature curve only 

 shows slight oscillations. Some patients have an occasional dry 

 cough, louder than that of broken wind. 



However slight the exudate, work soon produces dyspnoea ; the 

 animal becomes distressed, and finally stops for want of breath. These 

 symptoms grow more marked as the area of active lung is encroached 

 on by fluid exudate. Even when the pleura contains a considerable 

 quantity of liquid some animals, when at rest, show little change in the 

 character of the respiration ; but in the majoriity — especially when 

 exudate is abundant— the breathing is rapid and the "discordance" 

 striking. You have all noticed that in normal respiration the sides of 

 the chest and the flank move simultaneously and in the same direction 

 during both inspiration and expiration. The flank flattens slightly at 

 the same moment as the ribs are depressed, and bulges when they rise. 

 '*' Discordance " is said to exist when during expiration the flank bulges 

 while the ribs fall, and vice versa. This discordance is a common 

 symptom in various affections of the lungs and pleura, and in some 

 other very rare diseases, — in diaphragmatic hernia, for example. If 

 very marked it almost always indicates pleuritic exudate. 



Percussion of the thorax reveals the existence of a double-sided zone 

 of dulness which extends upwards to a greater or less distance, 

 reaching to — or even beyond — the centre line of the chest. Above this 

 zone the sounds are normal or tympanitic. 



On auscultation the dull area is usually silent, above this a tubal 

 sound is heard, and above this again the vesicular murmur. In 

 •exceptional cases where pleuritic adhesions exist a tubal murmur and 



