10 Circular 338, U. S. Department of Agriculture 



is Yariouslv recommended as a cure for demodectic mange or for 

 the inflamjnation of the skin accompanying it, consists in the daily 

 application of Lassar's paste, which is salicylic acid 2 parts, starch 

 24 parts, zinc oxide 24 parts, and white petrolatum 50 parts. Another 

 treatment consists in the use of a 1 to 5 per cent formaldehyde solu- 

 tion ; the dog is dipped in this or liberally sponged with it, Ihe dog's 

 eyes being protected, and the animal then coated with sulphur oint- 

 ment or petrolatum. This treatment is repeated every three or four 

 da^^s until four or five treatments have been given, the ointment being 

 removed before each formaldehyde bath. One objection to the use 

 of formaldehyde is that it is painful, having a sting comparable to 

 that of the formic acid of an ant bite. A treatment which has been 

 recommended recently consists in the use, once a week, of the follow- 

 ing preparation : Kerosene 8 ounces, raw linseed oil 

 8 ounces, carbolic acid 1 ounce, oil of tar 1 ounce, and 

 sulphur one-quarter of a pound ; this is applied with 

 mild rubbing. 



In connection with any medicinal treatment, the 

 supplementary measures noted under the subject of 

 sarcoptic mange should be used. In addition, the 

 treatment of the pustular tj^pe of demodectic mange 

 Fig. 7.— The com- should be begun by opening the pustules with a sharp 

 mon^ American knife and squccziug out the pus. Under some condi- 

 hicufa^' irritans'. ditions it has been recommended that the skin be 

 Ewkf|1?nd ii7rT- scarified and treated with tincture of iodine, but this 

 zen, 1918, after procedure should be left to the judgment of the 

 c r oT'^^measme- Veterinarian and carried out by him. Dogs are fairly 

 hatchVd ^1^'v/ susceptible to iodine poisoning. The pustular stage 

 330 long by 160 of mange is said to be greatly benefited in some cases 

 Srva, i.5^°mm^ by the injection of autogenous bacterins or stock 

 long by 3 20 mi- polyvalent bacterins of streptococcic and staphylo- 



cronswide. 1 J. . . - i • i n jt 



Measure m e n t s coccic bacteria oi strams isolated irom cases oi 

 H.^K^Ewin^g.)^^* demodectic mange, but the use of these bacterins 

 should be left to the veterinarian. Arsenic, in the 

 form of Fowler's solution, and sulphur are sometimes given inter- 

 nally for their effects on the sj^stem. Violet rays and even X-rays 

 have been used in demode<^tic mange, and good results reported in 

 some cases. 



CHIGGER INFESTATION 



Cause. — The common American chigger, Tromhicida irritans 

 (also called harvest mite), is a small, red or orange-yellow mite 

 (fig. 7) which as a six-legged larva (the adult mite has eight legs) 

 attacks man and the domesticated animals. It occurs from New York 

 to central Mexico and from the Atlantic Ocean to the Rocky Moun- 

 tains. A very closely related species occurs in the northern and 

 western part of this country. Chiggers have been thought to burrow 

 into the skin and die there, but recent investigations indicate that 

 they do not burrow, but merely attacli by the mouth parts, and if 

 left alone become engorged and fall off. 



Symptovis. — Chiggers cause intense itching and this results in 

 scratching and rubbing which in turn often results in the formation 



