OTITIS EXTERNA. 195 
quite sufficient for the purpose of this work to make but two divisions, and 
term inflammation of the external ear, otitis externa or external otitis, and 
inflammation beyond the drum membrane, otitis interna or internal otitis; the 
latter comprising all affections of this nature which occur in the middle and 
internal ear. 
OTITIS EXTERNA. 
Inflammation of the external ear is a common and often very obstinate affec- 
tion, from which no part of the canine race is exempt, although some breeds are 
more frequent victims than others, owing to the peculiar formation of the outer 
ears, which favors an increase in intensity of every trifling irritation therein. For 
instance, dogs with small, upright ears are less liable to suffer seriously from 
such trouble than others with long and heavily coated flaps, for the reason that 
the passage to the ears of the latter is not as well ventilated; moreover, when 
affected the long eared shake their heads more violently and often, and this 
aggravates the existing irritation, which even if trifling at first is thus prone to 
become severe. 
There are various degrees of severity of this affection. Thus in some cases 
there is scarcely any appreciable inflammation ; in some also it is of such mild- 
ness there is simply slight redness; while in others the inflammation is almost 
as severe as in erysipelas, and attended by deep redness and much swelling. 
Again, the inflammation may be limited to a small area, but generally it extends 
over the entire inner surface of the ear-flap and into the passage of the ear. 
This is the rule where the trouble has existed several days and there has been 
much scratching at the ear or shaking of the head. External otitis also varies 
much in character, for it may be a true eczema, or a mere congestion due to 
increase of blood in the parts, or an inflammation attended with an eruption of 
blisters, pimples or pustules, and even small abscesses. 
Various causes for otitis externa have been assigned, and include sudden 
chilling of the heated body, digestive disorders, improper food, over-eating, 
insufficient exercise, accumulation of the natural secretion, —the cerumen 
or wax —the presence of animal parasites and insects, a tendency to eczema, 
etc, 
The cause may be from without, as scratching, dirt, sand, or other irritating 
particles in the passage, direct injuries to the outer parts, as from a blow, or it 
may be simply an expression of some internal disorder, and of like nature to that 
which gives rise to eczema. 
During prolonged and severe attacks of distemper an eruption frequently 
appears on the skin, and in some instances the ears are invaded by it and otitis 
results. Indeed, there appears to be in all constitutional diseases of acute form 
