196 KENNEL DISEASES. 
in which eruptions occur on the skin, a special liability to inflammation of some 
portion of the ear. 
To include the vegetable parasite among the causes of otitis externa is strictly 
proper, because it sometimes gives rise to true inflammation. 
This parasite is a fungus growth or mould, something like that which accu- 
mulates on stones in damp cellars. It forms quite deeply within the passage, 
usually on the drum membrane and adjacent walls, lessens the hearing power, 
and excites in some cases itching and twinges of pain sufficiently intense to cause 
constant shaking of the head. 
The parasitic fungus in the ear passage is dependent upon the lodgment 
therein of its spores, which are doubtless conveyed in the air; yet it is evident 
that these spores would not germinate and increase rapidly unless they found 
favorable conditions. Precisely what constitutes such conditions is not known, 
and they may thrive where no abnormality about the passage can be detected, 
but it is safe to assume that dogs kept in damp and mouldy kennels or localities 
are the most favorably situated for harboring the fungus growths. 
In cases of sarcoptic mange, otitis externa is a frequent complication, and it 
is easy to believe that the ear trouble is induced by the same parasite which 
causes the affection of the skin. This insect appears in considerable numbers 
on the outer ear, and can be seen making its way in and out of the ear passage 
onto the skin. 
The detection of a tiny animal parasite in the ear has led to the conclusion on 
the part of some that otitis externa is sometimes contagious, and that the parasite 
is distinct from that which causes mange. No satisfactory evidence has been 
produced that otitis, fer se, is contagious. As found occurring with mange, when 
that disease has been transmitted of course the accompanying ear trouble may 
be set up. An inflammation of the ear also occasionally occurs in scarlet fever 
and measles, but although these diseases, like mange, are contagious, there is 
nothing to show that ear complication is necessarily likewise communicable. 
Furthermore, it has not been satisfactorily demonstrated that this parasite found 
in the ears of dogs decidedly differs from that which causes mange. 
Unless the ears are frequently examined, the first noticeable symptoms of 
otitis externa are likely to be shaking of the head, scratching at the ear, and rest- 
lessness. 
On examination the outer ear is usually simply reddened if the trouble is of 
recent origin, but it may be hot and swollen, even in such cases; and the longer 
otitis exists, as a rule, the more severe the inflammation. 
The notable exceptions to this rule are the cases caused by the presence of 
fungus growths, which may exist in an ear for a long time without giving rise to 
any appreciable inflammation. Such cases are not common, however, and in 
most instances of these growths a careful examination of the deeper parts of 
the ear passage reveals considerable redness and swelling; generally, also, the 
