432 Avian Diphtheria and Chicken Pox. 



on its surface, which gradually becomes thicker and forms dense 

 deposits, at first gray or yellowish, later brownish-gray and 

 dark brown on the parts exposed to the air; when dry, the 

 surface becomes rough and fissured. The membranes are 

 usually adherent to the subjacent tissue. When they are re- 

 moved they leave red, uneven, slightly depressed and bleeding 

 surfaces, or the mucosa is covered with cheesy easily removable 

 masses of exudate, and beneath these the surface is only red- 

 dened and finely granulated, but not eroded (usual appearance 

 in pigeons). 



The adjoining tissue which is not covered with membranes, 

 is edematous, but here also oftimes exudative masses occur in 

 the later stages; these gradually become confluent and finally 

 completely cover the affected cavity. Such abundant deposits 

 may occur within the first or second day, and after their removal 

 new ones form ; sometimes, however, the ulcerative process ex- 

 tends deeper leading to extensive destruction. If the animal 

 survives the membranes are in the course of time loosened spon- 

 taneously, and the loss of substance is replaced. 



Such croupous-diphtheritic membranes develop most com- 

 monly on the oral mucosa, especially on the gums near the longi- 

 tudinal cleft, on the borders and the under surface of tongue, 

 the corners of the mouth and cheeks, as well as on the pharyngeal 

 wall and in the vicinity of the larynx. The inflammatory process 

 not infrequently extends to the larynx and from here to the 

 trachea and bronchi; on the other hand it may extend from 

 the pharynx to the mucosa of the esophagus and crop. As 

 the inflammation progresses respiration and deglutition become 

 more and more difficult; the bird keeps its neck constantly 

 extended and the beak always open or opens it every few 

 moments gasping for air, whereby the in-rush of air is ac- 

 companied by whistling or rattling noises. In the meantime 

 the desire for food, at first unimpaired, grows less and less, and 

 as deglutition is more difficult or impossible, the bird ceases 

 to eat altogether. 



The affection of the nasal cavity is at first manifested by a 

 serous nasal discharge, which soon becomes muco-purulent and 

 later dirty-gray in color. It is discharged in considerable quan- 

 tity on pressure over the dorsum of the nose ; otherwise it dries 

 in the nasal orifices, closing these in part or entirely and oc- 

 casionally raising the upper nasal wall. In the meantime the 

 birds breathe heavily, show a desire to sneeze and shake their 

 heads thus hurling out masses of pus and single flecks of thick- 

 ened pus and bits of membranous shreds. From the nasal cavity 

 the inflammation extends to the lachrymal canal, which as a re- 

 sult becomes occluded ; it also progresses quite frequently on one 

 or both sides to the cella infraorbitalis which now becomes filled 

 with exudate and bulges under the internal angle of the eye in 

 the form of a growth, which on pressure discharges a muco- 

 purulent fluid from the nasal orifice on the affected side. The 



