NONCONTAGIOUS DISEASES OF RESPIRATORY ORGANS. 91 



marked difference in the normal or phj^siological pulse of the horse 

 and that of the cow, that of the horse being full and rather tense, 

 while in the cow it is soft and rolling. The pulse is faster in young 

 or old cattle than it is in those of middle age. 



Auscultation. — Auscultation and percussion are the chief methods 

 used to determine the various pathological changes that occur in 

 the respiratory organs. Auscultation is the act of listening, and 

 may be either mediate or immediate. Mediate auscultation is accom- 

 plished by aid of an instrument known as the stethoscope, one ex- 

 tremity of which is applied to the ear and the other to the chest of 

 the animal. In immediate auscultation the ear is aplied directly to 

 the part. Immediate auscultation will answer in a large majority of 

 cases. Ausculation is resorted to in cardiac and certain abdominal 

 diseases, but it is mainly employed for determining the condition of 

 the lungs and air passages. Animals can not give the various phases 

 of respiration, as can the patients of the human practitioner. The 

 organs themselves are less accessible than in man, owing to the 

 greater bulk of tissue surrounding them and the pectoral position of 

 the fore extremities, all of which render it more difficult in deter- 

 mining pathological conditions. (See PI. VIII.) 



The air going in and out of the lungs makes a certain soft, rustling 

 sound, known as the vesicular murmur, which can be heard distinctly 

 in a healthy state of the animal, especially upon inspiration. Exer- 

 cise accelerates the rate of respiration and intensifies this sound. 

 The vesicular murmur is heard only where the lung contains air and 

 its function is active. The vesicular murmur is weakened as inflam- 

 matory infiltration takes place and when the lungs are compressed by 

 fluids in the thoracic cavity, and disappears when the lung becomes 

 solidified in pneumonia or the chest cavity filled with fluid as in 

 hydrothorax. The bronchial murmur is a harsh, blowing sound, 

 heard in normal conditions by applying the ear over the lower part 

 of the trachea, and may be heard to a limited extent in the anterior 

 portions of the lungs after severe exercise. The bronchial murmur 

 when heard over other portions of the lungs generally signifies that 

 the lung tissue has become more or less solidified or that fluid has 

 collected in the chest cavity. 



Other sounds, known as mucous rales, are heard in the lungs in 

 pneumonia after the solidified parts begin to break down at the end 

 of the disease and in bronchitis where there is an excess of secretion, 

 as well as in other conditions. Mucous rales are of a gargling or 

 bubbling nature. They are caused by air rushing through tubes con- 

 taining secretions or pus. They are said to be large or small as they 

 are distinct or indistinct, depending upon the quantity of fluid that 

 is present and the size of the tubes in which the sound is produced. 



