474 PARASITIC SKIN DISEASES 



with blood. The eggs, commonly called nits, are firmly 

 glued to the hairs or feathers. The young are similar in 

 shape to the adults but only attain full size after several 

 changes. The females are larger and more numerous than 

 males. Phthiriasis or lousiness is a term applied to the con- 

 dition of an animal or bird infested with lice. Two kinds of 

 lice affect small animals: The Linognathus piliferus which 

 obtains nourishment by sucking blood, and the Trichodectes 

 latus which lives by eating the epidermal scales and hair. 

 The former may be recognized by its elongated head; the 

 head of the latter is short and broad. The common louse of 

 the dog is the Linognathus piliferus (Hematopinus piliferus), 

 which may also live on ferrets, and the Trichodectes latus. 

 The cat louse is Trichodectes subrostratus, and a rare species 

 of Linognathus piliferus is sometimes found on rabbits. 

 Several species of blood sucking lice infest fowls and birds, 

 chiefly the Menopum trigonocephalum, while a larger one, 

 the Menopum biseriatum, is most commonly found on the 

 heads of young chicks. By cohabitation of the different 

 species of fowls parasites peculiar to one of the species may 

 be found on others. Other animals or man coming in contact 

 with articles where lousy fowls roost will become infested, 

 but the lice soon leave their illegitimate host and the irritated 

 condition soon ends unless conditions favor further infesta- 

 tion as when straw is used from barns where fowls roost. 



Symptoms.— The blood-sucking louse causes the most 

 annoyance. Consequently dogs and fowls are the greatest 

 sufferers. The dog is not so frequently infested nor does 

 he suffer as much as fowls in which phthiriasis is a serious 

 condition, causing the birds to lose their rest and become 

 emaciated. It also interferes with the rearing of young. 

 While incubating, when conditions are ideal for a rapid 

 increase in these parasites, fowls suffer to such an extent as 

 to be compelled to leave the nest, or remaining, often die 

 from exhaustion from loss of blood and irritation. Newly 

 hatched chicks are frequent sufferers from large numbers of 

 lice especially the large ones on the head. The dog does not 

 seem to resent the presence of lice as much as fleas, hence 

 scratching and rubbing is less pronounced. A mild derma- 



