Mites Injurious to Domestic Animals. 23 



on each lobe, placed close together, are very wide and flattened 

 (spatulate) (fig. 6). 



The forms of Chorioptes are principally found on domestic 

 animals, viz., on horses, cattle, sheep, and goats. The author found 

 specimens of Ckorioptes on the feet of a Huanaco which died in 

 the Zoological Gardens, London, July, 1918. The forms of 

 Chorioptes are so similar that they probably belong to a single 

 species, of which they may be considered to be physiological 

 varieties (like the forms of Sar copies and Psoroptes communis), which, 

 although structurally alike, show a marked preference for their own 

 animal host. 



Chorioptic, or symbiotic mange as it is more commonly called, 

 is usually restricted to the feet or to the base of the tail and anal 

 fossa in cattle. In some cases it spreads on to the neck and back, 

 or on to the belly, perineum, etc. This mange is] usually of a 

 mild type, however, remaining localised and spreading but slowly. 

 Symbiotic mange in the horse is dealt with on page 34. 



Genus Otodectes, Canestrini, 1894. 



Very like Chorioptes, the suckers of the feet being borne on short 

 unsegmented peduncles as in that genus ; but the posterior lobes of 

 the body of the male are much less salient, and the hairs on them 

 are not spatulate. 



The mites of the genus Otodectes live in the ears of dogs, cats, 

 and ferrets. They are usually considered to be varieties of 

 a] single species (Otodectes cynotis, Hering), but apparently do not 

 differ from one another structurally. Otodectes cynotis, var felis, 

 Huber, 1861, is a very common parasite of London cats, and the 

 otitis caused by it is usually known as canker. A little olive oil 

 mixed with flowers of sulphur or a tenth part of naphthol should 

 be poured into the ears every few days until a cure is effected. 



Dogs used in hunting are especially liable to this kind of otitis 

 (0. cynotis var. canis (fig. 7)), which sometimes is the cause of fits 

 very similar to those due to epilepsy. The shape of the ear may 

 be altered by constant shaking, the lower lobe becoming much 

 thickened. 



A warm solution of potassium sulphide (10 grams in a litre of 

 water) should be poured twice daily into the ears of dogs suffering 

 from parasitic otitis, and a cure will be effected in a few days. 

 Before treatment the ears should be thoroughly cleansed, all visible 

 waxy secretions being removed. Infected dogs should be isolated 

 and the kennels disinfected. 



