PARASITES AND PARASITIC DISEASES OF DOGS 



Symptoms. — These mites puncture the tissues forming the external 

 canal of the ear and feed on the serum, causing an irritation which, 

 among other things, interferes with the normal production and dis- 

 persal of earwax. As a result the ear canal may 

 become filled with detritus, consisting of more 

 or less modified earwax and inflammatory prod- 

 ucts in the form of scales or powder. The mites 

 appear to begin operations in the region of the 

 eardrimi, but as they multiply the canal be- 

 comes more or less fUled with the mites, frass, 

 wax, and scales. The mites alone cause a mild 

 irritation and a pronoimced itching, but the 

 itching causes the dog to scratch and rub its 

 ears and shake its head, and these activities on 

 the part of the dog give rise to scratches, sores, 

 and bleeding. Affected dogs frequently whine 

 or howl, and in severe cases may show epilepti- 

 form spasms, travel in a circle, or show other 

 evidences of nervous disturbances. More or 

 less deafness may follow from the plugging of. 

 the ears and from injuries to them. Bacterial 

 comphcations may follow, and inflammation of 

 the middle and the inner ear and even of the 

 brain is said to occur in rare instances. The 



condition may be diagnosed by carefully removing 

 some of the material from the ears and finding mites 

 in it by examination with the naked eye, a hand lens, 

 or a microscope, or in earlier stages by recovering 

 these mites by carefully swabbing the region of the 

 eardrum with a pledget of cotton moistened with a 

 bland oil, or by examining the ears with a speculum 

 or otoscope in a good light with suitable illumination. 

 Treatment. — Treatment for ear mange is not espe- 

 cially difficult. If the ear is full of detritus, this should 

 be removed with forceps or a swab, taking care not 

 to injure the eardrimi. The ear canal can then be 

 liberally swabbed with a cotton pledget soaked in one 

 of the following preparations: 1 percent carbolic acid 

 or creosote in glycerin; 5 percent carbolic acid in olive 

 oil or castor oil ; 1 part carbon tetrachloride and 3 parts 

 castor oil; or 1 part chloroform in 9 parts olive oil or 

 castor oil. Kepeat treatment daily until the animal 

 is cured. 



FiGUBE 3.— The ear mite, Oto- 

 dectes cynoiis. Female. 

 Ventral view. Bnlarged- 

 From Banks, 1916. (Mi- 

 cron measurements: Male, 

 360 to 380 long by 250 to 280 

 wide; female 340 to 530 long 

 by 210 to 350 wide.) 



DEMODBCTIC MANGE 



FlGUBE 4.— The de- 

 modectic mange 

 mite, Demodex ca- 

 ms. Female. 

 Ventral view. En- 

 larged. From 

 Hirst, 1919. (Mi- 

 cron measure- 

 ments: Male, 220 to 

 260 long by 46 wide; 

 female, 180 to 300 

 long by 45 to .^5 

 wide.) 



Cause. — The mites, Demodex cards (synonym, D. 

 Jolliculorum var. canis), responsible for demodectic 

 mange, differ materially in form from those already 

 described, being elongated, vermiform objects (fig. 4). 

 They are very small and can be detected only by the 

 aid of the microscope. The diagnosis of demodectic 

 mange (follicular mange or red mange) may be made 

 by finding the mites in scrapings. _ The scrapings 

 must be deep enough to draw blood, as the mites live down in the 

 hair foUicles. The scrapings may be macerated in caustic and 



