8o Mites Injurious to Domestic Animals. 



in this vaiiety. There is also a form of the disease with circular 

 patches accompanied by large pustules. In a typical case there 

 are small hairless patches, together with reddish pimples and 

 pustules, skin hot and thickened in the affected places, etc. Dogs 

 suffering from follicular mange have a characteristic odour which 

 is very foul and disgusting. The complaint can easily be confused 

 with sarcoptic mange and also with certain fungoid afiections, but 

 the presence of the mites in large numbers is a distinguishing feature. 

 (For a more detailed account of the structure of the mite and of the 

 symptoms see Hirst, Studies on Acari No. 1. The genus Demodex, 

 Owen, 1919, 44 pp., 13 pis., and 4 text-figs.). 



Fig. 68. 



(a) Posterior end of dorsal .sliield of Liponyssus bursa, $ (p. 89). 



(b) Posterior end of dorsal shield of i. ««/ZwmrMm, J. (Original.) 



Demodex equi, Railliet, 1895. 

 (Fig. 49.) 



The Demodex found on the horse is a rather wide species, the 

 width being about a third of the total length. Spines on capitulum 

 slender, rod-like, and blunt at the end. 



Demodex equi is often present in horses which are apparently free 

 from disease. It seems clear, however, that this species can'^cause 

 a distinct pathogenic condition of the skin, characterised either by 

 pruritus, varying greatly in intensity, or by definite lesions ; these 

 symptoms may occur together or separately. The clinical effects 

 are as follows : — The coat is poor, with the hair very sparse in jjaces, 

 and there are peculiar bare-looking spots (rather like the marlcs 

 made by the bites of horse-lice) occurring chiefly where the hair is 



