590 



DISEASES OF THE SKIN. 



glasses of water — Martin), benzine, petroleum, fetid animal oil, de- 

 coction of walnut leaves or tobacco, bitter decoctions (absinth, gen- 

 tian, nux vomica), alcoholic extract of Persian insect powder. 



LICE (H-^MATOPINUS) AND TRICHODECTES. 



1. Lice are apterous insects, the tubular mouth of which is dis- 

 posed in the shape of a suction apparatus. They fix their eggs 

 (nits) upon the hair of animals which are affected by them. Most 

 of our domestic species nourish particular species of lice : the horse 

 is affected by the Hœmatopinus or Pediculus equi; the ox, by the 

 a. eurysternus and tenuirostris ; the pig suffers from the H, suis ; 

 the dog from the H. pilifer ; and the goat from the IT. stenopsis. 

 The selected regions of these parasites are the neck, back, the base 

 of the tail, and the neighborhood of the horns in the ox, and the 

 inner side of the hind legs in the pig. They are particularly fre- 

 quent in the dog and ox ; in the latter species they may be found 

 upon subjects which are perfectly well kept. In general, they 

 become easily and rapidly developed upon poorly fed, weak and 

 debilitated animals ; their presence is almost always a symptom of 

 insufficient care of the skin. They produce itching, partial depila- 

 tious ; besides, we observe nits in more or less large numbers, and 

 an abundant epidermic desquamation ; the animals often spread a 

 disagreeable odor, and, in the dog especially, the skin ends by 

 becoming covered with a viscous, impetiginous coating. 



2. Teichodectes do not suck the blood ; they attack the hair 

 and devour the epidermis. The head is larger than that of lice. 

 They locate in preference upon the head, the neck, and the legs. 

 We find special species of trichodectes in the dog (T. latus), the 

 horse (T. pilosus et parumpilosus), the ox {T. scalaris), the cat ( T. 

 subrostraius), the goat ( T. climax), and the sheep {T. sphœrocephalus). 

 This latter produces a very intense itching, which may lead to 

 suspicion of the existence of psoroptic mange. The principal thera- 

 peutic agents utilized for the destruction of hsematopinus and tri- 

 chodectes are: 1. Mercurial ointment. It maybe used in small 

 quantity for all domestic species, but it is especially appropriate for 

 the horse, pig, and dog. In the ox, which is very sensitive to 

 mercurial preparations, we have obtained good results by making 

 frictions upon the nape of the neck and the integument at the base 

 of the horns with five grammes of mercurial ointment ; we have 



