DISEASES OF POULTRY. 17 



COMMON CAUSES OF DISEASE. 



In order to act intelligently for the prevention and 

 cure of a disease, we must know something of its cause ; 

 and in order to determine the cause, we must know the 

 agencies which are liable to injuriously affect the dis- 

 eased organ. If it is found that the digestive organs 

 are affected, we are naturally led to inquire into the 

 character and quantity of food that has been taken ; the 

 amount of exercise which the birds have had ; whether 

 they have had access to gravel or grit ; whether the 

 alimentary canal is obstructed at any point ; whether 

 the affected birds have been unduly exposed to cold or 

 to draughts of air ; and, finally, whether they have been 

 attacked by any of the parasites, vegetable or animal, 

 which are known to cause disturbance of the digestive 

 functions. If the respiratory organs are diseased, it is 

 proper to inquire if the birds have been chilled or ex- 

 posed to draughts of air, or to a damp atmosphere; or 

 whether they are the prey of parasitic organisms such 

 as multiply in. this portion of the bird's body. If the 

 skin, comb, wattles, or feet are affected, the most likely 

 causes are freezing, mechanical injuries, and parasites. 

 If lameness is exhibited it is probably due to injuries 

 or rheumatism. If the general health is affected as 

 shown by mal -nutrition, paleness, and loss of weight, 

 the most common causes are indigestion from improper 

 food, and the attacks of internal or external parasites. 

 Diseases of the brain result from exposure to too great 

 heat, and sunstroke, from over exertion, and from too 

 high feeding with insufficient exercise. Diseases of 

 the ovaries and oviducts result.from the bird being too 

 fat; from these organs being over-stimulated, or from 

 the ration being improperly adjusted to the needs of 

 the body. 



