586 



DISEASES OF THE SKIN. 



CUTANEOUS DISEASES PRODUCED BY PILARIA 

 (THREADWORMS). 



1. In the horse we observe a particular disease of the skin which 

 is designated under the names of summer wounds^ pruriginous der- 

 matitis (Rivolta) granulous dermatitis (Laulanié). It well deserves 

 the last description, as it is characterized by granulations which 

 are related to the presence of nematode worms. Its first descrip- 

 tion, which is due to Ercolani, dates back to 1861 (Rivolta). The 

 integument is thickened and covered with vegetations containing 

 small encysted concretions easy of extraction. According to Lau- 

 lanié, the whole thickness of the skin is overrun with spheric or 

 elliptic granulations, the centre of which, having undergone fatty 

 degeneration, contains a spiral-shaped nematode worm, which is 

 marked by a characteristic transverse striation. In old granula- 

 tions this parasite is often destroyed, but it may preserve its vitality 

 for years (Laulanié). The process begins with a cellular infiltra- 

 tion of the subcutaneous connective tissue of the derma. The dis- 

 ease rétrocèdes during the winter, and is aggravated in summer 

 under the more active influence of the circulation. Rivolta thinks 

 that cure can only be obtained by the removal of diseased tissues. 

 Condamine and Drouilly have observed in the horse hemorrhagic 

 pimples produced by threadworms (see page 533, footnote). 



It is probable that some of the troubles described under the 

 name of tuberculous eruption by the ancients, especially by Haubner, 

 and sometimes mistaken for farcy, belong to the group of granulo- 

 verminous dermatites. 



2. In the dog, Siedamgrotzky observed a pustulous eruption 

 which was produced by nematode worms (nemathelminths). It 

 was located principally upon the external aspect of the legs. The 

 pustules, which were small, were surrounded by a red zone and 

 occasioned a very intense pruritus. They contained one, two, or 

 three embryos of nemathelminths, with a tapering or pointed tail, 

 0.04 to 0.7 millimetre in length, and coming undoubtedly from 

 hair follicles ; they have also been found upon the floor of the 

 stable, under the litter near adult subjects, and were about one 

 millimetre in length. Rivolta has also found filaria in several 

 ulcerous lesions of the dog's skin. 



Under the name of squamous herpes^ Semmer has described, in 



