PARASITIC CAXKER OF THE EAR 439 



Parasitic Canker of the Ear. 



{Parasitic Otitis.) 



Dermatophagus Canis. 



The symbiotes auriculans (canis) is a parasite that inhabits the ear 

 of the dog, causing an aggravated form of canicer (Nocard and Sewell). 

 The parasite which is common to the dog and cat is said to produce a 

 peculiar form of vertigo. 



The parasite differs from the common symbiot by the absence of 

 abdominal lobes in the male, which are represented by a notch which 

 has three bristles. The pubescent female has four pairs of legs which 

 are simple knobs. The male is 30 mm. long and 23 mm. wide, and the 

 female is 42 mm. long and 29 mm. wide (Neumann) (Fig. 158). 



Hering found moths (dermatophagus canis) in an ulcer of the ear 

 Avhich was accompanied by a deep-seated otitis. Nocard describes 

 minutely certain epileptiform fits in which the dog had a peculiar husky 

 cry and rushed about violently, running into various obstacles, and 

 finally fell insensible, and after a number of such attacks became totally 

 deaf. Sewell describes the condition as finding a collection of brown or 

 sooty-colored cerumen in the ear. If the inside of the ear is examined 

 closely a number of tin)^ white specks, the size of the eye of a needle, are 

 seen to be rapidly moving about the ear, and he believes that the tickling 

 sensation caused by these movements and the biting of the parasite are 

 what produce the irritation of the lining membranes of the ear. Boden 

 examined every case brought to the Dresden canine clinic, but failed to 

 find a case due to parasites. Frick after numerous examinations had 

 the same result. Cadiot and Newmann describe a parasite which causes 

 parasitic otitis (acariasis auricularis, otacariasis). 



Symptoms. — The ear is hot and slightly swollen, and on examination 

 it is hard to distinguish it from ordinary otitis. There is, however, less 

 discharge in this condition. The head is carried to one side, and the 

 animal will scratch the base of the ear very gently with its paw and whine 

 in a plaintive way. After having observed a number of animals infected 

 with the parasite, the writer is inclined to think that the carrying of the 

 head on one side and the gentle scratching of the ear are characteristic 

 of the disease, although it is quite as frequently seen in non-parasitic 

 otitis. The epileptiform symptoms described by Nocard have never 

 l)een observed. 



Treatment. — Nocard recommends naphthol 1 part, ether sulphuric 3 

 parts, and olive oil 10 parts. This should l)e injected into the external 

 auditory canal once daily, and the ear plugged up with cotton to prevent 

 the escape of the ether. The latter procedure is not advisable, for if the 



