264 DISEASES OF ANIMALS. 



shape is acquired ; the lungs become obstructec in theil 

 full play, and finally affected ; the unripe food produces 

 an unusual degree of serum in the abdomen, which is 

 diffused through many parts of the system, the miasma 

 of the low lands promoting the disease, and after awhile 

 the waste of the body falls into a tumor under the chin 

 called the poke. 



Hogg says, " Excess of fluid in those varieties of 

 grass which the animal selects for its food, and a defi 

 ciency of those firm, consistent kinds which are pecu- 

 liarly adapted for strengthening the stomach, for animat- 

 ing and establishing the muscular system, I take to be the 

 radical cause of this disorder ; yet secondary causes may 

 operate with such force and vigor as to unhinge the best 

 constitution, and dissolve the best constructed parts, and 

 when this is done, the rot is always the consequence." 



It prevails the most in cold seasons, especially when 

 cold dribbling rains come on soon after shearing. Flocks 

 not sheltered at night in unfavorable weather, are most 

 liable to this disease. "Want of food will also occa- 

 sion it, as well as eating grass full of unwholesome 

 plants. 



This disease is not common in this country, but in 

 Great Britain it is very frequent and fatal, causing the 

 destruction of many thousands annually. This difference 

 is doubtless owing to their moister climate, luxuriant 

 pastures, and artificial mode of feeding. Sheep do best 

 in dry climates, in dry seasons, and on high and dry 

 lands. Wet and dampness is destructive to them, espe- 

 cially if it be cold. In this country sheep are generally 

 kept on hilly lands, (and mostly on short pasturage,) 

 where the air and water are pure, and the herbage is 

 firm, sweet, and wholesome. On the flat and luxuriant 

 lands of the west, where the atmosphere and water are 

 less pure, and the herbage more luxuriant, the rot, in o 

 modified form, or some disease that resembles it, pre- 

 vails considerably. 



In some countries, rot is the most destructive disorder 

 to which sheep are liable. Some consider it infectious, 

 as it often spreads throughout the flock, and frequently 

 over a whole neighborhood; but this general preva 



