Etiology. Anatomical Changes. 483 



2. Dochmius stenocephalus, somewhat f~niallcr than the preceiling one. Tlic 

 head end pointed, mouth capsule corneal, provided with two pairs of small teeth on 

 the ventral side and with a longitudinal furrow on the dorsal side; the bursa of 

 the male similar to that of the preceding species. Male 6 to 8 mm., female S to 10 

 mm. long, ova 63 to 67 m by 32 to 38 /x- 



Whether Dochmius duodenal is, which 

 causes severe anemias in man, ever occurs in /'^^X /^^\. 



domestic animals is not yet known. / \ '^ - 



Development of Dochmii occurs 

 quite rapidly. From ova discharged 

 with feces, rhabditis-like embryos are 



developed in moist soil within 3 to 6 



days ; after hatching these develop pi„ gg q,.^ ^f Dochmius trio-ono- 



further in water or moist mud and cephalus (according to Railliet). 



become encysted. Tf they then get 



into the stomach of dogs they mature in the intestinal tract after three 



moults. 



Natural infection is caused by contaminated, niarsliy water. 

 Numerous ova contained in the feces of infected animals de- 

 velop when they get into water, and they are quite resistant. 

 One or two sick animals can, therefore, infect a whole pack or 

 a kennel. The disease is usually seen during- the Avarmer season, 

 but it may also make its onset in winter, as a case of the authors' 

 proves. Distemper or any debilitating disease forms, according 

 to Lignieres, a predisposing cause and prepares animals for 

 infection. Infection may, however, also take place through the 

 otherwise intact skin, as pointed out with reference to animals 

 by Lafon & Martin, a mode of infection demonstrated experi- 

 mentally in dogs by Cuille. 



Loos, Lambinet, Calmette & Breton and others have shown that infection 

 with Dochmius duodenalis (Anchylostomum duodenale) may occur through the intact 

 skin or from the subcutaneous connective tissue. 



Cuille placed encysted larvte of Dochmius trigonocephalus upon the shaved 

 thorax of experimental dogs; after a few minutes the animals manifested excite- 

 ment by howling and looking around towards the thorax, and rolling. These mani- 

 festations were caused by the irritation of the larvte which had penetrated into the 

 skin. The dogs became quiet after two hours, but the larva3 had in the meantime 

 penetrated into the skin, from where they got into the pulmonary capillai-ies with 

 the blood current. They then perforated the capillaries and got into the air vesicles, 

 from there into the bronchi, trachea and larynx, and finally into the pharynx, 

 esophagus and stomach. However, it appears more probable that they got into the 

 intestinal wall with arterial blood, and from there by perforation of capillaries into 

 the intestinal lumen. 



Edema and erythema, which are first seen at the place of infection, disappear 

 after 4 or 5 days, but on the day following the infestation the animals show an 

 inclination to vomit, they are depressed; after 5 or 6 days they become voracious, 

 suffer from bloody soft stools on the 10th day, and from the 12th to the ISth day 

 ova are found in the feces. Death occurs usually after 20 to 30 days in very 

 young animals, or in 10 days after a very numerous invasion. Larger dogs show the 

 symptoms of progressive anemia but remain alive for a long time. 



Anatomical Changes. At the point of attachment of the 

 worms one sees smaller or larger hemorrhages, sometimes, also, 

 hemorrhagic intestinal contents. The mucosa of the duodenum 

 and jejunum at first shows the picture of acute catarrh, later on 

 that of chronic inflammation, the intestinal wall becomes less 

 elastic, the lumen may occasionally be narrowed. In animals 



