I\ipiili)iiia. 



387 



tious cause is suspected for ccM-tain forms of papillomata because 

 the affection often appears in a number of animals at the same 

 time in one stalile in wide distribution over the cutaneous sur- 

 face; development after chronic .intiammatory irritation of tlie 

 skin has also been observed. Especiall}- in the skin of the udder 

 of the cow and in young- cattle, but also in other positions in this 

 species there often develop g-reat numbers of w^arty and nodular 

 papillomata which ma\- weigh en jiuissc many pounds. These 

 superficially divided growths, which are of course exposed to 

 traumatic influences and contamination 

 witli foul pus, are apt to become mal- 

 odorous from maceration of the desqua- 

 mated epiderm retained in the depres- 

 sions ; they often become oedematous 

 and swollen, and may become more or 

 less suppurative and putrefactive from 

 the influence of microorganisms, which 

 may have gained access into these 

 parts. In similar manner the jiapillo- 

 mata frequently developing in the frog 

 of the horse's hoof (known as hoof 

 cancer or frog cancer) are apt to break 

 down into a foul-smelling mass because 

 of incomplete keratinization of the 

 epithelial surface layer and contact with 

 all sorts of germs and putrid material 

 (dung, foul pus). 



A favorite location for these tumors 

 is the oesophagus of cattle, where the 

 papillfe project into the lumen of the 

 tube either as thorn-like, bristle-like or 

 brush-like prominences, or as circumscribed villous or coralline 

 growths, or as firm nodular bunches ; the passage of food, es- 

 pecially the return of the cud (in ruminants) being more or 

 less interfered with. Papillomata often occur also in the psalter 

 of cattle as berry-like, slightly cedematous, swollen-looking 

 growths, ranging in size from the millet seed size normal to the 

 papillae of the part, to pendant rosette-like bunches of projections 

 half the length of the finger, clul)-shapefl and covered smooth.ly 

 with epithelium. In dogs the lips, buccal cavity, foreskin and 

 anus are the principal sites of papillomata. 



Fig. ll.">. 



Congenital papillnma (if pinna 

 of colt. I After Troll- 

 denier.) 



