24 BULLETIN 260. U. S. DEPARTMENT OF AGRICULTURE. 



country, and is the usual host of Dioctophyme renale, the giant kid- 

 ney worm, which is a huge red worm a yard long and as thick as a 

 little finger, occurring in the kidney or abdominal cavity of man, the 

 cow, the horse, and the hog. This last-named worm has been found 

 in this country on a number of occasions. Strongyloides stercoralis, 

 the parasite of Cochin China diarrhea, can be readily transmitted to 

 dogs, and a Strongyloides, apparently this species, is found in dogs 

 in China and Japan. 



Mites, fleas, etc. — The dog is affected by a form of mange or scab 

 due to a mite known as Sarcoptes scabiei canis. This disease occurs 

 in this country and may be transmitted to man, causing more or less 

 discomfort. The dog is also laiown to be attacked by and transmit 

 the sarcoptic scab of sheep, a rather rare form of scab due to the mite 

 Sarcoptes scabiei ovis. 



In addition to being the adult host of the aberrant spiderlike form, 

 Linguatula rhinaria, the larva of which may occur in man, the dbg is 

 a host for the larval form of two closely related species, Porocephalus 

 armillatus and P. moniliformis, which may also pass their larval 

 stage in man. 



The dog is not only a host for the cosmopolitan fleas Pulex irritans 

 and Ctenocephalus canis, but is also a host for the widely distributed 

 chigger flea, or chigoe, Dermatophilus penetrans {Sarcopsylla pene- 

 trans), of tropical countries and native in the southern portion of 

 North America. This flea attacks men, cattle, horses, mules, sheep, 

 goats, and hogs, the female becoming embedded in the skin and grow- 

 ing to the size of a pea. 



Finally, the dog is an important host of the parasitic larvae of 

 certain flies which also habitually attack human beings and live 

 stock. One species, Derm,atobia cyanii^entris, occurs in South and 

 Central America, and another, Cordyloiia anthropophaga, occurs in 

 Africa. These larvae undergo their development beneath the skin, 

 causing boil-like tumors and abscesses, x^jiother species, Paralucilia 

 maeellaria {Chrysom,yia macellaria), is a serious pest in the southern 

 United States. Its larvae, commonly called screw worms, attack 

 cattle, horses, and other animals, including dogs and human beings: 

 These screw worms may undergo their development in the carcasses 

 of dead animals as well as in the tissues of live animals. 



CONCLUSION. 



The parasites discussed in this paper do not nearly exhaust the list 

 of those present in the dog, but only those known also to affect man 

 or live stock. 



In conclusion it may be said that the dog is at present the subject- 

 of numerous criticisms from three quarters. For over half a century 



