730 IOWA DEPARTMENT OF AGRICULTURE 



At this time the general health is not yet affected, and there is nothing 

 but the diphtheritic deposit to indicate that the bird has been attacked. 

 This deposit is at first thin, yellowish or whitish in color, and gradually 

 becomes thicker, firmer, and more adherent, so that considerable force is 

 required to remove it. The mucous membrane beneath the deposit is 

 found, when the latter is removed, to be inflamed, ulcerated, and bleed- 

 ing, but it is soon covered by a new deposit. This deposit is called a 

 false membrane, and when it is situated where the air passes over it 

 in breathing it dries, becomes uneven and fissured, and its color changes 

 to a dark brown. 



With pigeons the deposit is more friable and easily removed, and the 

 mucous membrane beneath it is reddened but not ulcerated. 



While the false membranes over the parts first affected are becoming 

 thicker, the inflammation extends to the adjoining surfaces, and new 

 diphtheritic centers develop, uniting with each other until the cheeks, the 

 tongue, the palate, the throat, and the inside of the nostrils are covered. 

 Very often the inflammation extends from the nostrils to the eyes and 

 the sacs beneath the eyes, and sometimes it penetrates the air tubes to 

 the lungs or the gullet to the crop. 



This extension of the disease leads to the appearance of other symp- 

 toms. The inflammation in the nostrils causes sneezing and the escape 

 of a thin, watery secretion from the nasal openings; the thick false mem- 

 branes fill up the nasal passages and the throat and obstruct the breath- 

 ing; a thick, viscid secretion collects on the eyelids and glues them to- 

 gether; the sacs under the eyes fill up, and swellings are caused which 

 disfigure the head; the poison which is produced by the growth of the 

 microbe beneath the false membranes is absorbed and affects the nervous 

 system, causing dullness, depression, and sleepiness. The affected bird 

 stands with the neck extended and the beak open to facilitate the en- 

 trance of air into the lungs, and from the corners of the mouth there 

 hang strings of thick, tenacious, grayish mucus. At this time, which 

 may be three to five days from the appearance of the first symptoms, 

 the condition is very serious. Swallowing is difficult or impossible; the 

 breathing is so obstructed that hardly sufficient air can be inhaled to 

 support life; the head is swollen; the eyes are nearly or entirely closed; 

 the feathers of the head, neck, and breast are foul with the decomposing 

 secretions from the nostrils and mouth; there is considerable fever; an 

 exhausting diarrhea sets in; there is rapid loss of weight; the comb and 

 wattles become pale and cold; the temperature of the body finally sinks 

 below the normal; and death soon follows. 



When false membranes form in the gullet, crop, and intestines, there 

 is a rapid aggravation of the symptoms, an intense diarrhea, and the 

 escape of blood with the droppings. This type of the disease is more 

 frequent with water fowl than other birds. Some fowls in a flock are 

 resistant, and after a few days of illness make a rapid recovery. Others 

 remain dull, weak, and thin in flesh, and may have more or less catarrh 

 and difiiculty of breathing for a long time. 



The period between exposure to the contagion and the appearance of 

 the first symptoms varies from 3 to 15 days; the duration of the dis- 



