92 DISEASES OF CATTLE. 



According to their cliaracter they are di\ided into dry and moist. 

 The friction sound is produced by the rubbing together of roughened 

 surfaces and is characteristic of pleurisy. 



Percussion. — Percussion is that mode of examination by which we 

 elicit sounds by striking or tapping over the part. It may be direct 

 or indirect. If the middle finger of the left hand is placed firmly on 

 the chest and smartly tapped or struck with the ends of the first three 

 fingers of the right hand, the sound will be noticed to be more reso- 

 nant and clear than when the same procedure is practiced on a solid 

 part of the body. This is because the lungs are not solid, but are 

 always, in health, w^ell expanded with air. In certain pulmonary 

 diseases, however, as in pneumonia, they fill up and become solid, 

 when percussion produces a dull sound, like that on any other solid 

 part of the animal. When fluid has collected in the lower part of 

 the chest cavity the sound will also be dull on percussion. "Where 

 there is an excess of air in the chest cavity, as in emphysema or in 

 pneumothorax, the percussion sound becomes abnormally loud and 

 clear. By practice on healthy animals the character and boimdaries 

 of the sounds can be so well determined that any variation from 

 them will be readily detected, and will sometimes disclose the pres- 

 ence of a diseased condition when nothing else ^\\\\. 



Percussion is sometimes practiced with the aid of a special per- 

 cussion hammer and an object known as a pleximeter to strike upon. 

 A percussion hammer is made of rubber or has a rubber tip, so that 

 when the pleximeter, which is placed against the side of the animal, 

 is struck the impact will not be accompanied with a noise. A percus- 

 sion hammer and pleximeter may be purchased from any veterinary 

 instrument maker. 



CATARRH (COLD IN THE HEAD). 



Xasal catarrh is an inflammation of the mucous membranes of the 

 nostrils and upper air passages. Simple catarrh is not a serious dis- 

 ease in itself, but if neglected is liable to be complicated with laryn- 

 gitis, bronchitis, pneumonia, plurisy, or other serious and sometimes 

 fatal diseases of the respiratory organs. Catarrh is a common 

 disease among cattle. It is often caused by sudden exposure to wet 

 and cold after they have been accustomed to shelter. It may arise 

 from inhalation of irritating gases. It is also sometimes produced 

 by certain specific atmospheric conditions, and may assume an 

 enzootic form. It is very debilitating, and requires prompt and 

 judicious treatment. 



Symptoms. — Kedness of the mucous membranes of the nose and 

 redness and watering of the eyes are symptoms of nasal catarrh. 

 The mucous membrane first becomes dry; afterwards a watery dis- 

 charge appears, and later, in severe cases, the discharge becomes 



